Summary:
Remove usages of asserting vector getters in Type in preparation for the
VectorType refactor. The existence of these functions complicates the
refactor while adding little value.
Reviewers: sdesmalen, rriddle, efriedma
Reviewed By: sdesmalen
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77263
Because this code does not use the IC-aware replaceInstUsesWith()
helper, we need to manually push users to the worklist.
This is NFC-ish, in that it may only change worklist order.
This patch adds a simplification if an OR weakens the overflow condition
for umul.with.overflow by treating any non-zero result as overflow. In that
case, we overflow if both umul.with.overflow operands are != 0, as in that
case the result can only be 0, iff the multiplication overflows.
Code like this is generated by code using __builtin_mul_overflow with
negative integer constants, e.g.
bool test(unsigned long long v, unsigned long long *res) {
return __builtin_mul_overflow(v, -4775807LL, res);
}
```
----------------------------------------
Name: D74141
%res = umul_overflow {i8, i1} %a, %b
%mul = extractvalue {i8, i1} %res, 0
%overflow = extractvalue {i8, i1} %res, 1
%cmp = icmp ne %mul, 0
%ret = or i1 %overflow, %cmp
ret i1 %ret
=>
%t0 = icmp ne i8 %a, 0
%t1 = icmp ne i8 %b, 0
%ret = and i1 %t0, %t1
ret i1 %ret
%res = umul_overflow {i8, i1} %a, %b
%mul = extractvalue {i8, i1} %res, 0
%cmp = icmp ne %mul, 0
%overflow = extractvalue {i8, i1} %res, 1
Done: 1
Optimization is correct!
```
Reviewers: nikic, lebedev.ri, spatel, Bigcheese, dexonsmith, aemerson
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D74141
As discussed on D73919, this replaces a few cases where we were
modifying multiple operands of instructions in-place with the
creation of a new instruction, which we generally prefer nowadays.
This tends to be more readable and less prone to worklist management
bugs.
Test changes are only superficial (instruction naming and order).
Adds a replaceOperand() helper, which is like Instruction.setOperand()
but adds the old operand to the worklist. This reduces the amount of
missing or incorrect worklist management.
This only applies the helper to a relatively small subset of
setOperand() calls in InstCombine, namely those of the pattern
`I.setOperand(); return &I;`, where it is most obviously applicable.
Differential Revision: https://reviews.llvm.org/D73803
This renames Worklist.AddDeferred() to Worklist.add() and
Worklist.Add() to Worklist.push(). The intention here is that
Worklist.add() should be the go-to method for explicit worklist
management, while the raw Worklist.push() is mostly for
InstCombine internals. I will then migrate uses of Worklist.push()
to Worklist.add() in followup changes.
As suggested by spatel on D73411 I'm also changing the remaining
method names to lowercase first character, in line with current
coding standards.
Differential Revision: https://reviews.llvm.org/D73745
This addresses https://bugs.llvm.org/show_bug.cgi?id=42801.
The m_c_ICmp() matcher is changed to provide the swapped predicate
if the operands are swapped.
Existing uses of m_c_ICmp() fall in one of two categories: Working
on equality predicates only, where swapping is irrelevant.
Or performing a manual swap, in which case this patch removes it.
The only exception is the foldICmpWithLowBitMaskedVal() fold, which
does not swap the predicate, and instead reasons about whether
a swap occurred or not for each predicate. Getting the swapped
predicate allows us to merge the logic for pairs of predicates,
instead of duplicating it.
Differential Revision: https://reviews.llvm.org/D72976
not (select ?, (cmp TPred, ?, ?), (cmp FPred, ?, ?) -->
select ?, (cmp TPred', ?, ?), (cmp FPred', ?, ?)
If both sides of the select are cmps, we can remove an instruction.
The case where only side is a cmp is deferred to a possible
follow-on patch.
We have a more general 'isFreeToInvert' analysis, but I'm not seeing
a way to use that more widely without inducing infinite looping
(opposing transforms).
Here, we flip the compare predicates directly, so we should not have
any danger by creating extra intermediate 'not' ops.
Alive proofs:
https://rise4fun.com/Alive/jKa
Name: both select values are compares - invert predicates
%tcmp = icmp sle i32 %x, %y
%fcmp = icmp ugt i32 %z, %w
%sel = select i1 %cond, i1 %tcmp, i1 %fcmp
%not = xor i1 %sel, true
=>
%tcmp_not = icmp sgt i32 %x, %y
%fcmp_not = icmp ule i32 %z, %w
%not = select i1 %cond, i1 %tcmp_not, i1 %fcmp_not
Name: false val is compare - invert/not
%fcmp = icmp ugt i32 %z, %w
%sel = select i1 %cond, i1 %tcmp, i1 %fcmp
%not = xor i1 %sel, true
=>
%tcmp_not = xor i1 %tcmp, -1
%fcmp_not = icmp ule i32 %z, %w
%not = select i1 %cond, i1 %tcmp_not, i1 %fcmp_not
Differential Revision: https://reviews.llvm.org/D72007
In this pattern, all the "magic" bits that we'd `add` are all
high sign bits, and in the value we'd be adding to they are all unset,
not unexpectedly, so we can have an `or` there:
https://rise4fun.com/Alive/ups
It is possible that `haveNoCommonBitsSet()` should be taught about this
pattern so that we never have an `add` variant, but the reasoning would
need to be recursive (because of that `select`), so i'm not really sure
that would be worth it just yet.
llvm-svn: 375378
https://rise4fun.com/Alive/KtL
This also shows that the fold added in D67412 / r372257
was too specific, and the new fold allows those test cases
to be handled more generically, therefore i delete now-dead code.
This is yet again motivated by
D67122 "[UBSan][clang][compiler-rt] Applying non-zero offset to nullptr is undefined behaviour"
llvm-svn: 372912
Summary:
This is again motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.
For
```
#include <cassert>
char* test(char& base, signed long offset) {
__builtin_assume(offset < 0);
return &base + offset;
}
```
We produce
https://godbolt.org/z/r40U47
and again those two icmp's can be merged:
```
Name: 0
Pre: C != 0
%adjusted = add i8 %base, C
%not_null = icmp ne i8 %adjusted, 0
%no_underflow = icmp ult i8 %adjusted, %base
%r = and i1 %not_null, %no_underflow
=>
%neg_offset = sub i8 0, C
%r = icmp ugt i8 %base, %neg_offset
```
https://rise4fun.com/Alive/ALaphttps://rise4fun.com/Alive/slnN
There are 3 other variants of this pattern,
i believe they all will go into InstSimplify.
https://bugs.llvm.org/show_bug.cgi?id=43259
Reviewers: spatel, xbolva00, nikic
Reviewed By: spatel
Subscribers: efriedma, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67849
llvm-svn: 372768
Summary:
This is again motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.
This pattern isn't exactly what we get there
(strict vs. non-strict predicate), but this pattern does not
require known-bits analysis, so it is best to handle it first.
```
Name: 0
%adjusted = add i8 %base, %offset
%not_null = icmp ne i8 %adjusted, 0
%no_underflow = icmp ule i8 %adjusted, %base
%r = and i1 %not_null, %no_underflow
=>
%neg_offset = sub i8 0, %offset
%r = icmp ugt i8 %base, %neg_offset
```
https://rise4fun.com/Alive/knp
There are 3 other variants of this pattern,
they all will go into InstSimplify:
https://rise4fun.com/Alive/bIDZhttps://bugs.llvm.org/show_bug.cgi?id=43259
Reviewers: spatel, xbolva00, nikic
Reviewed By: spatel
Subscribers: hiraditya, majnemer, vsk, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67846
llvm-svn: 372767
Summary:
Fold
or(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X)
into
X s> Y ? -1 : X
https://rise4fun.com/Alive/d8Ab
clamp255 is a common operator in image processing, can be implemented
in a shifty way "(255 - X) >> 31 | X & 255". Fold shift into select
enables more optimization, e.g., vmin generation for ARM target.
Reviewers: lebedev.ri, efriedma, spatel, kparzysz, bcahoon
Reviewed By: lebedev.ri
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67800
llvm-svn: 372678
Summary:
This is again motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.
In this particular case, given
```
char* test(char& base, unsigned long offset) {
return &base - offset;
}
```
it will end up producing something like
https://godbolt.org/z/luGEju
which after optimizations reduces down to roughly
```
declare void @use64(i64)
define i1 @test(i8* dereferenceable(1) %base, i64 %offset) {
%base_int = ptrtoint i8* %base to i64
%adjusted = sub i64 %base_int, %offset
call void @use64(i64 %adjusted)
%not_null = icmp ne i64 %adjusted, 0
%no_underflow = icmp ule i64 %adjusted, %base_int
%no_underflow_and_not_null = and i1 %not_null, %no_underflow
ret i1 %no_underflow_and_not_null
}
```
Without D67122 there was no `%not_null`,
and in this particular case we can "get rid of it", by merging two checks:
Here we are checking: `Base u>= Offset && (Base u- Offset) != 0`, but that is simply `Base u> Offset`
Alive proofs:
https://rise4fun.com/Alive/QOs
The `@llvm.usub.with.overflow` pattern itself is not handled here
because this is the main pattern, that we currently consider canonical.
https://bugs.llvm.org/show_bug.cgi?id=43251
Reviewers: spatel, nikic, xbolva00, majnemer
Reviewed By: xbolva00, majnemer
Subscribers: vsk, majnemer, xbolva00, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67356
llvm-svn: 372341
Summary:
I don't have a direct motivational case for this,
but it would be good to have this for completeness/symmetry.
This pattern is basically the motivational pattern from
https://bugs.llvm.org/show_bug.cgi?id=43251
but with different predicate that requires that the offset is non-zero.
The completeness bit comes from the fact that a similar pattern (offset != zero)
will be needed for https://bugs.llvm.org/show_bug.cgi?id=43259,
so it'd seem to be good to not overlook very similar patterns..
Proofs: https://rise4fun.com/Alive/21b
Also, there is something odd with `isKnownNonZero()`, if the non-zero
knowledge was specified as an assumption, it didn't pick it up (PR43267)
With this, i see no other missing folds for
https://bugs.llvm.org/show_bug.cgi?id=43251
Reviewers: spatel, nikic, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67412
llvm-svn: 372257
Summary:
This is rather unconventional..
As the comment there says, we don't have much folds for xor-of-icmps,
we try to turn them into an and-of-icmps, for which we have plenty of folds.
But if the ICmp we need to invert is not single-use - we give up.
As discussed in https://reviews.llvm.org/D65148#1603922,
we may have a non-canonical CLAMP pattern, with bit match and
select-of-threshold that we'll potentially clamp.
As it can be seen in `canonicalize-clamp-with-select-of-constant-threshold-pattern.ll`,
out of all 8 variations of the pattern, only two are **not** canonicalized into
the variant with and+icmp instead of bit math.
The reason is because the ICmp we need to invert is not single-use - we give up.
We indeed can't perform this fold at will, the general rule is that
we should not increase instruction count in InstCombine,
But we wouldn't end up increasing instruction count if we can adapt every other
user to the inverted value. This way the `not` we create **will** get folded,
and in the end the instruction count did not increase.
For that, of course, we need to look at the users of a Value,
which is again rather unconventional for InstCombine :S
Thus i'm proposing to be a little bit more insistive in `foldXorOfICmps()`.
The alternatives would be to not create that `not`, but add duplicate code to
manually invert all users; or to add some even less general combine to handle
some more specific pattern[s].
Reviewers: spatel, nikic, RKSimon, craig.topper
Reviewed By: spatel
Subscribers: hiraditya, jdoerfert, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65530
llvm-svn: 368685
We can treat icmp eq X, MIN_UINT as icmp ule X, MIN_UINT and allow
it to merge with icmp ugt X, C. Similar for the other constants.
We can do simliar for icmp ne X, (U)INT_MIN/MAX in foldAndOfICmps. And we already handled UINT_MIN there.
Fixes PR42691.
Differential Revision: https://reviews.llvm.org/D65017
llvm-svn: 366945
For equality, the function called getTrue/getFalse with the VT
of the comparison input. But getTrue/getFalse need the boolean VT.
So if this code ever executed, it would assert.
I believe these cases are removed by InstSimplify so we don't get here.
So this patch just fixes up an assert to exclude the equality
possibility and removes the broken code.
llvm-svn: 366649
AddOne/SubOne create new Constant objects. That seems heavy for
comparing ConstantInts which wrap APInts. Just do the math on
on the APInts and compare them.
llvm-svn: 366648
This is the Demorgan'd 'not' of the pattern handled in:
D63660 / rL364153
This is another intermediate IR step towards solving PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
We can test if a value is not a power-of-2 using ctpop(X) > 1,
so combining that with an is-zero check of the input is the
same as testing if not exactly 1 bit is set:
(X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1
llvm-svn: 364246
This is another intermediate IR step towards solving PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
We can test if a value is power-of-2-or-0 using ctpop(X) < 2,
so combining that with a non-zero check of the input is the
same as testing if exactly 1 bit is set:
(X != 0) && (ctpop(X) u< 2) --> ctpop(X) == 1
Differential Revision: https://reviews.llvm.org/D63660
llvm-svn: 364153
We have a similar match for patterns ending in a truncate. This
should be ok for all targets because the default expansion would
still likely be better from replacing 2 'and' ops with 1.
Attempt to show the logic equivalence in Alive (which doesn't
currently have funnel-shift in its vocabulary AFAICT):
%shamt = zext i8 %i to i32
%m = and i32 %shamt, 31
%neg = sub i32 0, %shamt
%and4 = and i32 %neg, 31
%shl = shl i32 %v, %m
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
=>
%a = and i8 %i, 31
%shamt2 = zext i8 %a to i32
%neg2 = sub i32 0, %shamt2
%and4 = and i32 %neg2, 31
%shl = shl i32 %v, %shamt2
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
https://rise4fun.com/Alive/V9r
llvm-svn: 360605
If they have other users we'll just end up increasing the instruction count.
We might be able to weaken this to only one of them having a single use if we can prove that the and will be removed.
Fixes PR41164.
Differential Revision: https://reviews.llvm.org/D59630
llvm-svn: 356690
Combine 2 fcmps that are checking for nan-ness:
and (fcmp ord X, 0), (and (fcmp ord Y, 0), Z) --> and (fcmp ord X, Y), Z
or (fcmp uno X, 0), (or (fcmp uno Y, 0), Z) --> or (fcmp uno X, Y), Z
This is an exact match for a minimal reassociation pattern.
If we want to handle this more generally that should go in
the reassociate pass and allow removing this code.
This should fix:
https://bugs.llvm.org/show_bug.cgi?id=41069
llvm-svn: 356471
This bug seems to be harmless in release builds, but will cause an error in UBSAN
builds or an assertion failure in debug builds.
When it gets to this opcode comparison, it assumes both of the operands are BinaryOperators,
but the prior m_LogicalShift will also match a ConstantExpr. The cast<BinaryOperator> will
assert in a debug build, or reading an invalid value for BinaryOp from memory with
((BinaryOperator*)constantExpr)->getOpcode() will cause an error in a UBSAN build.
The test I added will fail without this change in debug/UBSAN builds, but not in release.
Patch by: @AndrewScheidecker (Andrew Scheidecker)
Differential Revision: https://reviews.llvm.org/D58049
llvm-svn: 353736
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
This is matching the equivalent of the DAG expansion,
so it should never end up with worse perf than the
original code even if the target doesn't have a rotate
instruction.
llvm-svn: 350672
There are potential improvements to the structure of this API
raised by D54994, but remove some cosmetic blemishes before
making any functional changes.
llvm-svn: 348149
The original patch was committed here:
rL344609
...and reverted:
rL344612
...because it did not properly check/test data types before calling
ComputeNumSignBits().
The tests that caused bot failures for the previous commit are
over-reaching front-end tests that run the entire -O optimizer
pipeline:
Clang :: CodeGen/builtins-systemz-zvector.c
Clang :: CodeGen/builtins-systemz-zvector2.c
I've added a negative test here to ensure coverage for that case.
The new early exit check also tests the type of the 'B' parameter,
so we don't waste time on matching if either value is unsuitable.
Original commit message:
This is part of solving PR37549:
https://bugs.llvm.org/show_bug.cgi?id=37549
The patterns shown here are a special case of something
that we already convert to select. Using ComputeNumSignBits()
catches that case (but not the more complicated motivating
patterns yet).
The backend has hooks/logic to convert back to logic ops
if that's better for the target.
llvm-svn: 345149
I noticed a missing check and added it at rL344610, but there actually
are codegen tests that will fail without that, so I'll edit those and
submit a fixed patch with more tests.
llvm-svn: 344612
This is part of solving PR37549:
https://bugs.llvm.org/show_bug.cgi?id=37549
The patterns shown here are a special case of something
that we already convert to select. Using ComputeNumSignBits()
catches that case (but not the more complicated motivating
patterns yet).
The backend has hooks/logic to convert back to logic ops
if that's better for the target.
llvm-svn: 344609
This allows the xor to be removed completely.
This might help with recomitting r341674, but seems good regardless.
Coincidentally fixes PR38915.
Differential Revision: https://reviews.llvm.org/D51964
llvm-svn: 342163
If the ~X wasn't able to simplify above the max/min, we might be able to simplify it by moving it below the max/min.
I had to modify the ~(min/max ~X, Y) transform to prevent getting stuck in a loop when we saw the new ~(max/min X, ~Y) before the ~Y had been folded away to remove the new not.
Differential Revision: https://reviews.llvm.org/D51398
llvm-svn: 341674
This fold is needed to avoid a regression when we try
to recommit rL300977.
We can't see the most basic win currently because
demanded bits changes the patterns:
https://rise4fun.com/Alive/plpp
llvm-svn: 341559
I'm probably missing some way to use m_Deferred to remove the code
duplication, but that can be a follow-up.
The improvement in demand_shrink_nsw.ll is an example of missing
the fold because the pattern matching was deficient. I didn't try
to follow the bits in that test, but Alive says it's correct:
https://rise4fun.com/Alive/ugc
llvm-svn: 341426
This is just a cleanup step. The TODO comments show
what is wrong with the 'and' version of the fold.
Fixing this should be part of recommitting:
rL300977
llvm-svn: 341405
The fold was implemented for the general case but use-limitation,
but the later constant version which didn't check uses was only
matching splat constants.
llvm-svn: 341292
This is no-outwardly-visible-change intended, so no test.
But the code is smaller and more efficient. The check for
a 'not' op is intended to avoid the expensive value tracking
call when it should not be necessary, and it might prevent
infinite looping when we resurrect:
rL300977
llvm-svn: 341280
I'm assuming its easier to make sure the RHS of an XOR is all ones than it is to check for the many select patterns we have. So lets check that first. Same with the one use check.
llvm-svn: 340321
Summary:
This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250):
```
signed char test(unsigned int x) { return x; }
```
`clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3`
* Old: {F6904292}
* With this patch: {F6904294}
General pattern:
X & Y
Where `Y` is checking that all the high bits (covered by a mask `4294967168`)
are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0`
Pattern can be one of:
%t = add i32 %arg, 128
%r = icmp ult i32 %t, 256
Or
%t0 = shl i32 %arg, 24
%t1 = ashr i32 %t0, 24
%r = icmp eq i32 %t1, %arg
Or
%t0 = trunc i32 %arg to i8
%t1 = sext i8 %t0 to i32
%r = icmp eq i32 %t1, %arg
This pattern is a signed truncation check.
And `X` is checking that some bit in that same mask is zero.
I.e. can be one of:
%r = icmp sgt i32 %arg, -1
Or
%t = and i32 %arg, 2147483648
%r = icmp eq i32 %t, 0
Since we are checking that all the bits in that mask are the same,
and a particular bit is zero, what we are really checking is that all the
masked bits are zero.
So this should be transformed to:
%r = icmp ult i32 %arg, 128
The transform itself ended up being rather horrible, even though i omitted some cases.
Surely there is some infrastructure that can help clean this up that i missed?
https://rise4fun.com/Alive/3Ou
The initial commit (rL339610)
was reverted, since the first assert was being triggered.
The @positive_with_extra_and test now has coverage for that case.
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: RKSimon, erichkeane, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D50465
llvm-svn: 339621
At least one buildbot was able to actually trigger that assert
on the top of the function. Will investigate.
This reverts commit r339610.
llvm-svn: 339612
Summary:
This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250):
```
signed char test(unsigned int x) { return x; }
```
`clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3`
* Old: {F6904292}
* With this patch: {F6904294}
General pattern:
X & Y
Where `Y` is checking that all the high bits (covered by a mask `4294967168`)
are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0`
Pattern can be one of:
%t = add i32 %arg, 128
%r = icmp ult i32 %t, 256
Or
%t0 = shl i32 %arg, 24
%t1 = ashr i32 %t0, 24
%r = icmp eq i32 %t1, %arg
Or
%t0 = trunc i32 %arg to i8
%t1 = sext i8 %t0 to i32
%r = icmp eq i32 %t1, %arg
This pattern is a signed truncation check.
And `X` is checking that some bit in that same mask is zero.
I.e. can be one of:
%r = icmp sgt i32 %arg, -1
Or
%t = and i32 %arg, 2147483648
%r = icmp eq i32 %t, 0
Since we are checking that all the bits in that mask are the same,
and a particular bit is zero, what we are really checking is that all the
masked bits are zero.
So this should be transformed to:
%r = icmp ult i32 %arg, 128
https://rise4fun.com/Alive/3Ou
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: RKSimon, erichkeane, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D50465
llvm-svn: 339610
Summary: computeKnownBits is expensive. The cases that would be detected by the computeKnownBits portion of haveNoCommonBitsSet were already handled by the earlier call to SimplifyDemandedInstructionBits.
Reviewers: spatel, lebedev.ri
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D50604
llvm-svn: 339531
Summary:
https://rise4fun.com/Alive/IT3
Comes up in the [most ugliest] `signed int` -> `signed char` case of
`-fsanitize=implicit-conversion` (https://reviews.llvm.org/D50250)
Previously, we were stuck with `not`: {F6867736}
But now we are able to completely get rid of it: {F6867737}
(FIXME: why are we loosing the metadata? that seems wrong/strange.)
Here, we only want to do that it we will be able to completely
get rid of that 'not'.
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: vsk, erichkeane, llvm-commits
Differential Revision: https://reviews.llvm.org/D50301
llvm-svn: 339243
This fold was written in an odd way and tried to avoid
an endless loop by bailing out on all constants instead
of the supposedly problematic case of -1. But (X & -1)
should always be simplified before we reach here, so I'm
not sure how that is a problem.
There were no tests for the commuted patterns, so I added
those at rL338364.
llvm-svn: 338367
The tests with constants show a missing optimization.
Analysis for adds is better than subs, so this can also
help with other transforms. And codegen is better with
adds for targets like x86 (destructive ops, no sub-from).
https://rise4fun.com/Alive/llK
llvm-svn: 338118
This bug was created by rL335258 because we used to always call instsimplify
after trying the associative folds. After that change it became possible
for subsequent folds to encounter unsimplified code (and potentially assert
because of it).
Instead of carrying changed state through instcombine, we can just return
immediately. This allows instsimplify to run, so we can continue assuming
that easy folds have already occurred.
llvm-svn: 336965
This is outwardly NFC from what I can tell, but it should be more efficient
to simplify first (despite the name, SimplifyAssociativeOrCommutative does
not actually simplify as InstSimplify does - it creates/morphs instructions).
This should make it easier to refactor duplicated code that runs for all binops.
llvm-svn: 335258
The bug report:
https://bugs.llvm.org/show_bug.cgi?id=36036
...requests a DAG change for this, but an IR canonicalization
probably handles most cases. If we still want to match this
pattern in the backend, there's a proposal for that too:
D47831
Alive proofs including nsw/nuw cases that were first noted in:
D46988
https://rise4fun.com/Alive/Kmp
This patch is largely copied from the existing code that was
initially added with:
D40984
...but I didn't see much gain from trying to share code.
llvm-svn: 334137
Review feedback from r328165. Split out just the one function from the
file that's used by Analysis. (As chandlerc pointed out, the original
change only moved the header and not the implementation anyway - which
was fine for the one function that was used (since it's a
template/inlined in the header) but not in general)
llvm-svn: 333954
As noted in the review thread for rL333782, we could have
made a bug harder to hit if we were simplifying instructions
before trying other folds.
The shuffle transform in question isn't ever a simplification;
it's just a canonicalization. So I've renamed that to make that
clearer.
This is NFCI at this point, but I've regenerated the test file
to show the cosmetic value naming difference of using
instcombine's RAUW vs. the builder.
Possible follow-ups:
1. Move reassociation folds after simplifies too.
2. Refactor common code; we shouldn't have so much repetition.
llvm-svn: 333820
In post-commit review, Eric Christopher notes that many
new MSan warnings are being observed with this patch.
The probable reason is: if 'y' is undef here and we could
evaluate it twice and get different results.
We can't increase the number of uses of a value.
llvm-svn: 333631
Summary:
Finally fixes [[ https://bugs.llvm.org/show_bug.cgi?id=6773 | PR6773 ]].
Now that the backend is all done, we can finally fold it!
The canonical unfolded masked merge pattern is
```(x & m) | (y & ~m)```
There is a second, equivalent variant:
```(x | ~m) & (y | m)```
Only one of them (the or-of-and's i think) is canonical.
And if the mask is not a constant, we should fold it to:
```((x ^ y) & M) ^ y```
https://rise4fun.com/Alive/ndQw
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: nicholas, RKSimon, llvm-commits
Differential Revision: https://reviews.llvm.org/D46814
llvm-svn: 333106
According to alive this is valid. I'm hoping to use this to make an assumption that the sign bit is zero after this sequence. The only way it wouldn't be is if the input was INT__MIN, but by preserving the flags we can make doing this to INT_MIN UB.
The nuw flags is weird because it creates such a contradiction that the original number would have to be positive meaning we could remove the select entirely, but we don't get that far.
Differential Revision: https://reviews.llvm.org/D46988
llvm-svn: 332623
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
llvm-svn: 331272
Summary:
As discussed in D45733, we want to do this in InstCombine.
https://rise4fun.com/Alive/LGk
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: chandlerc, xbolva00, llvm-commits
Differential Revision: https://reviews.llvm.org/D45867
llvm-svn: 331205
Summary:
Masked merge has a pattern of: `((x ^ y) & M) ^ y`.
But, there is no difference between `((x ^ y) & M) ^ y` and `((x ^ y) & ~M) ^ x`,
We should canonicalize the pattern to non-inverted mask.
https://rise4fun.com/Alive/Yol
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45664
llvm-svn: 331112
Summary:
Currently, we
1. match `LHS` matcher to the `first` operand of binary operator,
2. and then match `RHS` matcher to the `second` operand of binary operator.
If that does not match, we swap the `LHS` and `RHS` matchers:
1. match `RHS` matcher to the `first` operand of binary operator,
2. and then match `LHS` matcher to the `second` operand of binary operator.
This works ok.
But it complicates writing of commutative matchers, where one would like to match
(`m_Value()`) the value on one side, and use (`m_Specific()`) it on the other side.
This is additionally complicated by the fact that `m_Specific()` stores the `Value *`,
not `Value **`, so it won't work at all out of the box.
The last problem is trivially solved by adding a new `m_c_Specific()` that stores the
`Value **`, not `Value *`. I'm choosing to add a new matcher, not change the existing
one because i guess all the current users are ok with existing behavior,
and this additional pointer indirection may have performance drawbacks.
Also, i'm storing pointer, not reference, because for some mysterious-to-me reason
it did not work with the reference.
The first one appears trivial, too.
Currently, we
1. match `LHS` matcher to the `first` operand of binary operator,
2. and then match `RHS` matcher to the `second` operand of binary operator.
If that does not match, we swap the ~~`LHS` and `RHS` matchers~~ **operands**:
1. match ~~`RHS`~~ **`LHS`** matcher to the ~~`first`~~ **`second`** operand of binary operator,
2. and then match ~~`LHS`~~ **`RHS`** matcher to the ~~`second`~ **`first`** operand of binary operator.
Surprisingly, `$ ninja check-llvm` still passes with this.
But i expect the bots will disagree..
The motivational unittest is included.
I'd like to use this in D45664.
Reviewers: spatel, craig.topper, arsenm, RKSimon
Reviewed By: craig.topper
Subscribers: xbolva00, wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D45828
llvm-svn: 331085
This is the last step in getting constant pattern matchers to allow
undef elements in constant vectors.
I'm adding a dedicated m_ZeroInt() function and building m_Zero() from
that. In most cases, calling code can be updated to use m_ZeroInt()
directly when there's no need to match pointers, but I'm leaving that
efficiency optimization as a follow-up step because it's not always
clear when that's ok.
There are just enough icmp folds in InstSimplify that can be used for
integer or pointer types, that we probably still want a generic m_Zero()
for those cases. Otherwise, we could eliminate it (and possibly add a
m_NullPtr() as an alias for isa<ConstantPointerNull>()).
We're conservatively returning a full zero vector (zeroinitializer) in
InstSimplify/InstCombine on some of these folds (see diffs in InstSimplify),
but I'm not sure if that's actually necessary in all cases. We may be
able to propagate an undef lane instead. One test where this happens is
marked with 'TODO'.
llvm-svn: 330550
Summary:
In order to get the whole fold as specified in [[ https://bugs.llvm.org/show_bug.cgi?id=6773 | PR6773 ]],
let's first handle the simple straight-forward things.
Let's start with the `and` -> `or` simplification.
The one obvious thing missing here: the constant mask is not handled.
I have an idea how to handle it, but it will require some thinking,
and is not strictly required here, so i've left that for later.
https://rise4fun.com/Alive/Pkmg
Reviewers: spatel, craig.topper, eli.friedman, jingyue
Reviewed By: spatel
Subscribers: llvm-commits
Was reviewed as part of https://reviews.llvm.org/D45631
llvm-svn: 330103
Remove #include of Transforms/Scalar.h from Transform/Utils to fix layering.
Transforms depends on Transforms/Utils, not the other way around. So
remove the header and the "createStripGCRelocatesPass" function
declaration (& definition) that is unused and motivated this dependency.
Move Transforms/Utils/Local.h into Analysis because it's used by
Analysis/MemoryBuiltins.cpp.
llvm-svn: 328165
getNumUses is a linear time operation. It traverses the user linked list to the end and counts as it goes. Since we are only interested in small constant counts, we should use hasNUses or hasNUsesMore more that terminate the traversal as soon as it can provide the answer.
There are still two other locations in InstCombine, but changing those would force a rebase of D44266 which if accepted would remove them.
Differential Revision: https://reviews.llvm.org/D44398
llvm-svn: 327315
Also, rename 'foldOpWithConstantIntoOperand' because that's annoyingly
vague. The constant check is redundant in some cases, but it allows
removing duplication for most of the calls.
llvm-svn: 326329
This is guarded by shouldChangeType(), so the tests show that
we don't do the fold if the narrower type is not legal. Note
that there is a proposal (D42424) that would change the results
for the specific cases shown in these tests. That difference is
also discussed in PR35792:
https://bugs.llvm.org/show_bug.cgi?id=35792
Alive proofs for the cases handled here as well as the bitwise
logic binops that we should already do better on:
https://rise4fun.com/Alive/c97https://rise4fun.com/Alive/Lc5Ehttps://rise4fun.com/Alive/kdf
llvm-svn: 323437
We want to do this for 2 reasons:
1. Value tracking does not recognize the ashr variant, so it would fail to match for cases like D39766.
2. DAGCombiner does better at producing optimal codegen when we have the cmp+sel pattern.
More detail about what happens in the backend:
1. DAGCombiner has a generic transform for all targets to convert the scalar cmp+sel variant of abs
into the shift variant. That is the opposite of this IR canonicalization.
2. DAGCombiner has a generic transform for all targets to convert the vector cmp+sel variant of abs
into either an ABS node or the shift variant. That is again the opposite of this IR canonicalization.
3. DAGCombiner has a generic transform for all targets to convert the exact shift variants produced by #1 or #2
into an ISD::ABS node. Note: It would be an efficiency improvement if we had #1 go directly to an ABS node
when that's legal/custom.
4. The pattern matching above is incomplete, so it is possible to escape the intended/optimal codegen in a
variety of ways.
a. For #2, the vector path is missing the case for setlt with a '1' constant.
b. For #3, we are missing a match for commuted versions of the shift variants.
5. Therefore, this IR canonicalization can only help get us to the optimal codegen. The version of cmp+sel
produced by this patch will be recognized in the DAG and converted to an ABS node when possible or the
shift sequence when not.
6. In the following examples with this patch applied, we may get conditional moves rather than the shift
produced by the generic DAGCombiner transforms. The conditional move is created using a target-specific
decision for any given target. Whether it is optimal or not for a particular subtarget may be up for debate.
define i32 @abs_shifty(i32 %x) {
%signbit = ashr i32 %x, 31
%add = add i32 %signbit, %x
%abs = xor i32 %signbit, %add
ret i32 %abs
}
define i32 @abs_cmpsubsel(i32 %x) {
%cmp = icmp slt i32 %x, zeroinitializer
%sub = sub i32 zeroinitializer, %x
%abs = select i1 %cmp, i32 %sub, i32 %x
ret i32 %abs
}
define <4 x i32> @abs_shifty_vec(<4 x i32> %x) {
%signbit = ashr <4 x i32> %x, <i32 31, i32 31, i32 31, i32 31>
%add = add <4 x i32> %signbit, %x
%abs = xor <4 x i32> %signbit, %add
ret <4 x i32> %abs
}
define <4 x i32> @abs_cmpsubsel_vec(<4 x i32> %x) {
%cmp = icmp slt <4 x i32> %x, zeroinitializer
%sub = sub <4 x i32> zeroinitializer, %x
%abs = select <4 x i1> %cmp, <4 x i32> %sub, <4 x i32> %x
ret <4 x i32> %abs
}
> $ ./opt -instcombine shiftyabs.ll -S | ./llc -o - -mtriple=x86_64 -mattr=avx
> abs_shifty:
> movl %edi, %eax
> negl %eax
> cmovll %edi, %eax
> retq
>
> abs_cmpsubsel:
> movl %edi, %eax
> negl %eax
> cmovll %edi, %eax
> retq
>
> abs_shifty_vec:
> vpabsd %xmm0, %xmm0
> retq
>
> abs_cmpsubsel_vec:
> vpabsd %xmm0, %xmm0
> retq
>
> $ ./opt -instcombine shiftyabs.ll -S | ./llc -o - -mtriple=aarch64
> abs_shifty:
> cmp w0, #0 // =0
> cneg w0, w0, mi
> ret
>
> abs_cmpsubsel:
> cmp w0, #0 // =0
> cneg w0, w0, mi
> ret
>
> abs_shifty_vec:
> abs v0.4s, v0.4s
> ret
>
> abs_cmpsubsel_vec:
> abs v0.4s, v0.4s
> ret
>
> $ ./opt -instcombine shiftyabs.ll -S | ./llc -o - -mtriple=powerpc64le
> abs_shifty:
> srawi 4, 3, 31
> add 3, 3, 4
> xor 3, 3, 4
> blr
>
> abs_cmpsubsel:
> srawi 4, 3, 31
> add 3, 3, 4
> xor 3, 3, 4
> blr
>
> abs_shifty_vec:
> vspltisw 3, -16
> vspltisw 4, 15
> vsubuwm 3, 4, 3
> vsraw 3, 2, 3
> vadduwm 2, 2, 3
> xxlxor 34, 34, 35
> blr
>
> abs_cmpsubsel_vec:
> vspltisw 3, -16
> vspltisw 4, 15
> vsubuwm 3, 4, 3
> vsraw 3, 2, 3
> vadduwm 2, 2, 3
> xxlxor 34, 34, 35
> blr
>
Differential Revision: https://reviews.llvm.org/D40984
llvm-svn: 320921
This is a preliminary step towards solving the remaining part of PR27145 - IR for isfinite():
https://bugs.llvm.org/show_bug.cgi?id=27145
In order to solve that one more generally, we need to add matching for and/or of fcmp ord/uno
with a constant operand.
But while looking at those patterns, I realized we were missing a canonicalization for nonzero
constants. Rather than limiting to just folds for constants, we're adding a general value
tracking method for this based on an existing DAG helper.
By transforming everything to 0.0, we can simplify the existing code in foldLogicOfFCmps()
and pick up missing vector folds.
Differential Revision: https://reviews.llvm.org/D37427
llvm-svn: 312591
In addition to removing chunks of duplicated code, we don't
want these to diverge. If there's a fold for one, there
should be a fold of the other via DeMorgan's Laws.
llvm-svn: 312420
We had these locals:
Value *Op0RHS = LHS->getOperand(1);
Value *Op1LHS = RHS->getOperand(0);
...so we confusingly transposed the meaning of left/right and op0/op1.
llvm-svn: 312418
This makes it easier to see that they're almost duplicates.
As with the similar icmp functions, there should be identical
folds for both logic ops because those are DeMorganized variants.
llvm-svn: 312415
A future patch will make the code look through truncates feeding the compare. So the compares might be different types but the pretruncated types might be the same.
This should be safe because we still require the same Value* to be used truncated or not in both compares. So that serves to ensure the types are the same.
llvm-svn: 312381
Previously we used the type from the LHS of the compare, but a future patch will change decomposeBitTestICmp to look through truncates so it will return a pretruncated Value* and the type needs to match that.
llvm-svn: 312380
Looks like for 'and' and 'or' we end up performing at least some of the transformations this is bocking in a round about way anyway.
For 'and sext(cmp1), sext(cmp2) we end up later turning it into 'select cmp1, sext(cmp2), 0'. Then we optimize that back to sext (and cmp1, cmp2). This is the same result we would have gotten if shouldOptimizeCast hadn't blocked it. We do something analogous for 'or'.
With this patch we allow that transformation to happen directly in foldCastedBitwiseLogic. And we now support the same thing for 'xor'. This is definitely opening up many other cases, but since we already went around it for some cases hopefully it's ok.
Differential Revision: https://reviews.llvm.org/D36213
llvm-svn: 311508
I don't think there's any reason to have them scattered about and on all 4 operands. We already have an early check that both compares must be the same type. And within a given compare the LHS and RHS must have the same type. Beyond that I don't think there's anyway this function returns anything valid for pointer types. So let's just return early and be done with it.
Differential Revision: https://reviews.llvm.org/D36561
llvm-svn: 311383
This recommits r310869, with the moved files and no extra changes.
Original commit message:
This addresses a fixme in InstSimplify about using decomposeBitTest. This also fixes InstSimplify to handle ugt and ult compares too.
I've modified the interface a little to return only the APInt version of the mask that InstSimplify needs. InstCombine now has a small wrapper routine to create a Constant out of it. I've also dropped the returning of 0 since InstSimplify doesn't need that. So InstCombine creates a zero constant itself.
I also had to make decomposeBitTest support vectors since InstSimplify needs that.
As InstSimplify can't use something from the Transforms library, I've moved the CmpInstAnalysis code to the Analysis library.
Differential Revision: https://reviews.llvm.org/D36593
llvm-svn: 310889
Failed to add the two files that moved. And then added an extra change I didn't mean to while trying to fix that. Reverting everything.
llvm-svn: 310873
This addresses a fixme in InstSimplify about using decomposeBitTest. This also fixes InstSimplify to handle ugt and ult compares too.
I've modified the interface a little to return only the APInt version of the mask that InstSimplify needs. InstCombine now has a small wrapper routine to create a Constant out of it. I've also dropped the returning of 0 since InstSimplify doesn't need that. So InstCombine creates a zero constant itself.
I also had to make decomposeBitTest support vectors since InstSimplify needs that.
As InstSimplify can't use something from the Transforms library, I've moved the CmpInstAnalysis code to the Analysis library.
Differential Revision: https://reviews.llvm.org/D36593
llvm-svn: 310869
Summary:
These functions were overly complicated. The body of this function was rechecking for an And operation to find the constant, but we already knew we were looking at two Ands ORed together and the pieces are in variables. We already had earlier nearby code that checked for ConstantInts. So just inline the remaining parts into the earlier code.
Next step is to use m_APInt instead of ConstantInt.
Reviewers: spatel, efriedma, davide, majnemer
Reviewed By: spatel
Subscribers: zzheng, llvm-commits
Differential Revision: https://reviews.llvm.org/D36439
llvm-svn: 310806
This also corrects the description to match what was actually implemented. The old comment said X^(C1|C2), but it implemented X^((C1|C2)&~(C1&C2)). I believe ((C1|C2)&~(C1&C2)) is equivalent to (C1^C2).
Differential Revision: https://reviews.llvm.org/D36505
llvm-svn: 310658
We used to try to truncate the constant vector to vXi1, but if it's already i1 this would fail. Instead we now use IRBuilder::getZExtOrTrunc which should check the type and only create a trunc if needed. I believe this should trigger constant folding in the IRBuilder and ultimately do the same thing just with the additional type check.
llvm-svn: 310639
Note the original code I deleted incorrectly listed this as (X | C1) & C2 --> (X & C2^(C1&C2)) | C1 Which is only valid if C1 is a subset of C2. This relied on SimplifyDemandedBits to remove any extra bits from C1 before we got to that code.
My new implementation avoids relying on that behavior so that it can be naively verified with alive.
Differential Revision: https://reviews.llvm.org/D36384
llvm-svn: 310272
Summary:
The (not (sext)) case is really (xor (sext), -1) which should have been simplified to (sext (xor, 1)) before we got here. So we shouldn't need to handle it.
With that taken care of we only need to two cases so don't need the swap anymore. This makes us in sync with the equivalent code in visitOr so inline this to match.
Reviewers: spatel, eli.friedman, majnemer
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D36240
llvm-svn: 310063
As far as I can tell this should be handled by foldCastedBitwiseLogic which is called later in visitXor.
Differential Revision: https://reviews.llvm.org/D36214
llvm-svn: 309882
This adds support for sext in foldLogicCastConstant. This is a prerequisite for D36214.
Differential Revision: https://reviews.llvm.org/D36234
llvm-svn: 309880
Summary:
If one side simplifies to the identity value for inner opcode, we can replace the value with just the operation that can't be simplified.
I've removed a couple now unneeded special cases in visitAnd and visitOr. There are probably other cases I missed.
Reviewers: spatel, majnemer, hfinkel, dberlin
Reviewed By: spatel
Subscribers: grandinj, llvm-commits, spatel
Differential Revision: https://reviews.llvm.org/D35451
llvm-svn: 308111
Previously the InstCombiner class contained a pointer to an IR builder that had been passed to the constructor. Sometimes this would be passed to helper functions as either a pointer or the pointer would be dereferenced to be passed by reference.
This patch makes it a reference everywhere including the InstCombiner class itself so there is more inconsistency. This a large, but mechanical patch. I've done very minimal formatting changes on it despite what clang-format wanted to do.
llvm-svn: 307451
Going through the Constant methods requires redetermining that the Constant is a ConstantInt and then calling isZero/isOne/isMinusOne.
llvm-svn: 307292
Bswap isn't a simple operation so we need to make sure we are really removing a call to it before doing these simplifications.
For the case when both LHS and RHS are bswaps I've allowed it to be moved if either LHS or RHS has a single use since that at least allows us to move it later where it might find another bswap to combine with and it decreases the use count on the other side so maybe the other user can be optimized.
Differential Revision: https://reviews.llvm.org/D34974
llvm-svn: 307273
Summary:
I came across this while thinking about what would happen if one of the operands in this xor pattern was itself a inverted (A & ~B) ^ (~A & B)-> (A^B).
The patterns here assume that the (~a | ~b) will be demorganed to ~(a & b) first. Though I wonder if there's a multiple use case that would prevent the demorgan.
Reviewers: spatel
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34870
llvm-svn: 306967
There are two conditions ORed here with similar checks and each contain two matches that must be true for the if to succeed. With the commutable match on the first half of the OR then both ifs basically have the same first part and only the second part distinguishs. With this change we move the commutable match to second half and make the first half unique.
This caused some tests to change because we now produce a commuted result, but this shouldn't matter in practice.
llvm-svn: 306800
If the components of the and/or had multiple uses, this transform created an additional instruction.
This patch makes sure we remove one of the components.
Differential Revision: https://reviews.llvm.org/D34498
llvm-svn: 306027
There are 2 parts to this patch made simultaneously to avoid a regression.
We're reversing the canonicalization that moves bitwise vector ops before bitcasts.
We're moving bitwise vector ops *after* bitcasts instead. That's the 1st and 3rd hunks
of the patch. The motivation is that there's only one fold that currently depends on
the existing canonicalization (see next), but there are many folds that would
automatically benefit from the new canonicalization.
PR33138 ( https://bugs.llvm.org/show_bug.cgi?id=33138 ) shows why/how we have these
patterns in IR.
There's an or(and,andn) pattern that requires an adjustment in order to continue matching
to 'select' because the bitcast changes position. This match is unfortunately complicated
because it requires 4 logic ops with optional bitcast and sext ops.
Test diffs:
1. The bitcast.ll and bitcast-bigendian.ll changes show the most basic difference -
bitcast comes before logic.
2. There are also tests with no diffs in bitcast.ll that verify that we're still doing
folds that were enabled by the previous canonicalization.
3. icmp-xor-signbit.ll shows the payoff. We don't need to adjust existing icmp patterns
to look through bitcasts.
4. logical-select.ll contains several tests for the or(and,andn) --> select fold to
verify that we are still handling those cases. The lone diff shows the movement of
the bitcast from the new canonicalization rule.
Differential Revision: https://reviews.llvm.org/D33517
llvm-svn: 306011
We have a large portfolio of folds for and-of-icmps and or-of-icmps in InstSimplify and InstCombine,
but hardly anything for xor-of-icmps. Rather than trying to rethink and translate all of those folds,
we can use the truth table definition of xor:
X ^ Y --> (X | Y) & !(X & Y)
...to see if we can convert the xor to and/or and then use the existing folds.
http://rise4fun.com/Alive/J9v
Differential Revision: https://reviews.llvm.org/D33342
llvm-svn: 305792
Summary:
These 4 patterns have the same one use check repeated twice for each. Once without a cast and one with. But the cast has no effect on what method is called.
For the OR case I believe it is always profitable regardless of the number of uses since we'll never increase the instruction count.
For the AND case I believe it is profitable if the pair of xors has one use such that we'll get rid of it completely. Or if the C value is something freely invertible, in which case the not doesn't cost anything.
Reviewers: spatel, majnemer
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34308
llvm-svn: 305705
Summary: This is the demorganed version of the case we already handle for the OR of iszero.
Reviewers: spatel
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34244
llvm-svn: 305548
Currently we expect A to be on the same side in both Ands but nothing guarantees that.
While there also switch to using matchers for some of the code.
Differential Revision: https://reviews.llvm.org/D34230
llvm-svn: 305487
Summary: This matches the behavior we already had for compares and makes us consistent everywhere.
Reviewers: dberlin, hfinkel, spatel
Reviewed By: dberlin
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33604
llvm-svn: 305049
We have wrappers for several other ValueTracking methods that take care of passing all of the analysis and assumption cache parameters. This extends it to isKnownToBeAPowerOfTwo.
llvm-svn: 303924
Also, fix the old-style capitalization of the related functions
and move them to the 'private' section of the class since they
are just helpers of the visit* functions.
As shown in the post-commit comments for D32143, we are missing
folds for xor-of-icmps.
llvm-svn: 303381
// (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
This canonicalization was added at:
https://reviews.llvm.org/rL7264
By moving xors out/down, we can more easily combine constants. I'm adding
tests that do not change with this patch, so we can verify that those kinds
of transforms are still happening.
This is no-functional-change-intended because there's a later fold:
// (X^C)|Y -> (X|Y)^C iff Y&C == 0
...and demanded-bits appears to guarantee that any fold that would have
hit the fold we're removing here would be caught by that 2nd fold.
Similar reasoning was used in:
https://reviews.llvm.org/rL299384
The larger motivation for removing this code is that it could interfere with
the fix for PR32706:
https://bugs.llvm.org/show_bug.cgi?id=32706
Ie, we're not checking if the 'xor' is actually a 'not', so we could reverse
a 'not' optimization and cause an infinite loop by altering an 'xor X, -1'.
Differential Revision: https://reviews.llvm.org/D33050
llvm-svn: 302733
The motivation for getting rid of dyn_castNotVal is to allow fixing:
https://bugs.llvm.org/show_bug.cgi?id=32706
So this was supposed to be functional-change-intended for the case
of inverting constants and applying DeMorgan. However, I can't find
any cases where that pattern will actually get to matchDeMorgansLaws()
because we have other folds in visitAnd/visitOr that do the same
thing. So this ends up just being a clean-up patch with slight efficiency
improvement, but no-functional-change-intended.
llvm-svn: 302581
This is another step towards getting rid of dyn_castNotVal,
so we can recommit:
https://reviews.llvm.org/rL300977
As the tests show, we were missing the lshr case for constants
and both ashr/lshr vector splat folds. The ashr case with constant
was being performed inefficiently in 2 steps. It's also possible
there was a latent bug in that case because we can't do that fold
if the constant is positive:
http://rise4fun.com/Alive/Bge
llvm-svn: 302465
We can simplify (or (icmp X, C1), (icmp X, C2)) to 'true' or one of the icmps in many cases.
I had to check some of these with Alive to prove to myself it's right, but everything seems
to check out. Eg, the deleted code in instcombine was completely ignoring predicates with
mismatched signedness.
This is a follow-up to:
https://reviews.llvm.org/rL301260https://reviews.llvm.org/D32143
llvm-svn: 302370
This was originally checked in here:
https://reviews.llvm.org/rL301923
And reverted here:
https://reviews.llvm.org/rL301924
Because there's a clang test that would fail after this. I fixed/removed the
offending CHECK lines in:
https://reviews.llvm.org/rL301928
So let's try this again. Original commit message:
This is the fold that causes the infinite loop in BoringSSL
(https://github.com/google/boringssl/blob/master/crypto/cipher/e_rc2.c)
when we fix instcombine demanded bits to prefer 'not' ops as in https://reviews.llvm.org/D32255.
There are 2 or 3 problems with dyn_castNotVal, and I don't think we can
reinstate https://reviews.llvm.org/D32255 until dyn_castNotVal is completely eliminated.
1. As shown here, it transforms 'not' into random xor. This transform is harmful to SCEV and codegen because 'not' can often be folded while random xor cannot.
2. It does not transform vector constants. This is actually a good thing, but if you don't believe the above argument, then we shouldn't have excluded vectors.
3. It tries to avoid transforming not(not(X)). That's nice, but it doesn't match the greedy nature of instcombine. If we DeMorganize a pattern that has an extra 'not' in it: ~(~(~X) & Y) --> (~X | ~Y)
That's just another case of DeMorgan, so we should trust that we'll fold that pattern too: (~X | ~ Y) --> ~(X & Y)
Differential Revision: https://reviews.llvm.org/D32665
llvm-svn: 301929
This is the fold that causes the infinite loop in BoringSSL
(https://github.com/google/boringssl/blob/master/crypto/cipher/e_rc2.c)
when we fix instcombine demanded bits to prefer 'not' ops as in D32255.
There are 2 or 3 problems with dyn_castNotVal, and I don't think we can
reinstate D32255 until dyn_castNotVal is completely eliminated.
1. As shown here, it transforms 'not' into random xor. This transform is
harmful to SCEV and codegen because 'not' can often be folded while
random xor cannot.
2. It does not transform vector constants. This is actually a good thing,
but if you don't believe the above argument, then we shouldn't have
excluded vectors.
3. It tries to avoid transforming not(not(X)). That's nice, but it doesn't
match the greedy nature of instcombine. If we DeMorganize a pattern
that has an extra 'not' in it:
~(~(~X) & Y) --> (~X | ~Y)
That's just another case of DeMorgan, so we should trust that we'll fold
that pattern too:
(~X | ~ Y) --> ~(X & Y)
Differential Revision: https://reviews.llvm.org/D32665
llvm-svn: 301923
If we have ~(~X & Y), it only makes sense to transform it to (X | ~Y) when we do not need
the intermediate (~X & Y) value. In that case, we would need an extra instruction to
generate ~Y + 'or' (as shown in the test changes).
It's ok if we have multiple uses of ~X or Y, however. In those cases, we may not reduce the
instruction count or critical path, but we might improve throughput because we can generate
~X and ~Y in parallel. Whether that actually makes perf sense or not for a target is something
we can't answer in IR.
Differential Revision: https://reviews.llvm.org/D32703
llvm-svn: 301848
The matching here wasn't able to handle all the possible commutes. It always assumed the not would be on the left of the xor, but that's not guaranteed.
Differential Revision: https://reviews.llvm.org/D32474
llvm-svn: 301316
We can simplify (and (icmp X, C1), (icmp X, C2)) to one of the icmps in many cases.
I had to check some of these with Alive to prove to myself it's right, but everything
seems to check out. Eg, the code in instcombine was completely ignoring predicates with
mismatched signedness.
Handling or-of-icmps would be a follow-up step.
Differential Revision: https://reviews.llvm.org/D32143
llvm-svn: 301260
This is a straight cut and paste, but there's a bigger problem: if this
fold exists for simplifyOr, there should be a DeMorganized version for
simplifyAnd. But more than that, we have a patchwork of ad hoc logic
optimizations in InstCombine. There should be some structure to ensure
that we're not missing sibling folds across and/or/xor.
llvm-svn: 301213
We handled all of the commuted variants for plain xor already,
although they were scattered around and sometimes folded less
efficiently using distributive laws. We had no folds for not-xor.
Handling all of these patterns consistently is part of trying to
reinstate:
https://reviews.llvm.org/rL300977
llvm-svn: 301144
There's probably some better way to write this that eliminates the
code duplication without hurting readability, but at least this
eliminates the logic holes and is hopefully slightly more efficient
than creating new instructions.
llvm-svn: 301129
The later uses of dyn_castNotVal in this block are either
incomplete (doesn't handle vector constants) or overstepping
(shouldn't handle constants at all), but this first use is
just unnecessary. 'I' is obviously not a constant, and it
can't be a not-of-a-not because that would already be
instsimplified.
llvm-svn: 301088
getSignBit is a static function that creates an APInt with only the sign bit set. getSignMask seems like a better name to convey its functionality. In fact several places use it and then store in an APInt named SignMask.
Differential Revision: https://reviews.llvm.org/D32108
llvm-svn: 300856
So, `cast<Instruction>` is not guaranteed to succeed. Change the
code so that we create a new constant and use it in the newly
created instruction, as it's done in other places in InstCombine.
OK'ed by Sanjay/Craig. Fixes PR32686.
llvm-svn: 300495
...when C1 differs from C2 by one bit and C1 <u C2:
http://rise4fun.com/Alive/Vuo
And move related folds to a helper function. This reduces code duplication and
will make it easier to remove the scalar-only restriction as a follow-up step.
llvm-svn: 300364
This is effectively a retry of:
https://reviews.llvm.org/rL299851
but now we have tests and an assert to make sure the bug
that was exposed with that attempt will not happen again.
I'll fix the code duplication and missing sibling fold next,
but I want to make this change as small as possible to reduce
risk since I messed it up last time.
This should fix:
https://bugs.llvm.org/show_bug.cgi?id=32524
llvm-svn: 300236
It's less efficient to produce 'ule' than 'ult' since we know we're going to
canonicalize to 'ult', but we shouldn't have duplicated code for these folds.
As a trade-off, this was a pretty terrible way to make a '2'. :)
if (LHSC == SubOne(RHSC))
AddC = ConstantExpr::getSub(AddOne(RHSC), LHSC);
The next steps are to share the code to fix PR32524 and add the missing 'and'
fold that was left out when PR14708 was fixed:
https://bugs.llvm.org/show_bug.cgi?id=14708
llvm-svn: 300222
One potential way to make InstCombine (very slightly?) faster is to recycle instructions
when possible instead of creating new ones. It's not explicitly stated AFAIK, but we don't
consider this an "InstSimplify". We could, however, make a new layer to house transforms
like this if that makes InstCombine more manageable (just throwing out an idea; not sure
how much opportunity is actually here).
Differential Revision: https://reviews.llvm.org/D31863
llvm-svn: 300067
Also, make the same change in and-of-icmps and remove a hack for detecting that case.
Finally, add some FIXME comments because the code duplication here is awful.
This should fix the remaining IR problem noted in:
https://bugs.llvm.org/show_bug.cgi?id=32524
llvm-svn: 299851
"PredicatesFoldable" returns false for signed/unsigned mismatched pairs,
so these cases should never exist. We'll default to 'unreachable' on those
predicate combos instead.
Most of what's left in these switches belongs in InstSimplify (and may
already be there), so there's probably more that can be done to reduce
this code.
llvm-svn: 299829
This combine is fully handled by SimplifyDemandedInstructionBits as of r299658 where I fixed this code to ensure the Add/Sub had only a single user. Otherwise it would fire and create additional instructions. That fix resulted in an improvement to code generated for tsan which is why I committed it before deleting.
Differential Revision: https://reviews.llvm.org/D31543
llvm-svn: 299704
There must be some opportunity to refactor big chunks of nearly duplicated code in FoldOrOfICmps / FoldAndOfICmps.
Also, none of this works with vectors, but it should.
llvm-svn: 299568
Currently we only fold with ConstantInt RHS. This generalizes to any Constant RHS.
Differential Revision: https://reviews.llvm.org/D31610
llvm-svn: 299466
It turns out that SimplifyDemandedInstructionBits will get called earlier and remove bits from C1 first. Effectively doing (X & (C1&C2)) | C2. So by the time it got to this check there could be no common bits.
I think the DAGCombiner has the same check but its check can be executed because it handles demanded bits later. I'll look at it next.
llvm-svn: 299384
1. Improve enum, function, and variable names.
2. Improve comments.
3. Fix variable capitalization.
4. Run clang-format.
As an existing code comment suggests, this should work with vector types / splat constants too,
so making this look right first will reduce the diffs needed for that change.
llvm-svn: 299365
The callers have already performed the necessary cast before calling. This allows us to remove a comment that says the instruction must be a BinaryOperator and make it explicit in the argument type.
Had to add a default case to the switch because BinaryOperator::getOpcode() returns a BinaryOps enum.
llvm-svn: 299339
As far as I can tell this combine is fully handled by SimplifyDemandedInstructionBits.
I was only looking at this because it is the only user of APIntOps::isShiftedMask which is itself broken. As demonstrated by r299187. I was going to fix isShiftedMask and needed to make sure we had coverage for the new cases it would expose to this combine. But looks like we can nuke it instead.
Differential Revision: https://reviews.llvm.org/D31543
llvm-svn: 299337
This removes a parameter from the routine that was responsible for a lot of the issue. It was a bit count that had to be set to the BitWidth of the APInt and would get passed to getLowBitsSet. This guaranteed the call to getLowBitsSet would create an all ones value. This was then compared to (V | (V-1)). So the only shifted masks we detected had to have the MSB set.
The one in tree user is a transform in InstCombine that never fires due to earlier transforms covering the case better. I've submitted a patch to remove it completely, but for now I've just adapted it to the new interface for isShiftedMask.
llvm-svn: 299273
Now that we call ShrinkDemandedConstant on the RHS of sub this should be taken care of. This code doesn't trigger on any in tree regressions, but did before ShrinkDemandedConstant was added to the RHS.
llvm-svn: 298644
Some of the callers are artificially limiting this transform to integer types;
this should make it easier to incrementally remove that restriction.
llvm-svn: 291620
Background/motivation - I was circling back around to:
https://llvm.org/bugs/show_bug.cgi?id=28296
I made a simple patch for that and noticed some regressions, so added test cases for
those with rL281055, and this is hopefully the minimal fix for just those cases.
But as you can see from the surrounding untouched folds, we are missing commuted patterns
all over the place, and of course there are no regression tests to cover any of those cases.
We could sprinkle "m_c_" dust all over this file and catch most of the missing folds, but
then we still wouldn't have test coverage, and we'd still miss some fraction of commuted
patterns because they require adjustments to the match order.
I'm aware of the concern about the potential compile-time performance impact of adding
matches like this (currently being discussed on llvm-dev), but I don't think there's any
evidence yet to suggest that handling commutative pattern matching more thoroughly is not
a worthwhile goal of InstCombine.
Differential Revision: https://reviews.llvm.org/D24419
llvm-svn: 290067
A number of new patterns for simplifying and/xor of icmp:
(icmp ne %x, 0) ^ (icmp ne %y, 0) => icmp ne %x, %y if the following is true:
1- (%x = and %a, %mask) and (%y = and %b, %mask)
2- %mask is a power of 2.
(icmp eq %x, 0) & (icmp ne %y, 0) => icmp ult %x, %y if the following is true:
1- (%x = and %a, %mask1) and (%y = and %b, %mask2)
2- Let %t be the smallest power of 2 where %mask1 & %t != 0. Then for any
%s that is a power of 2 and %s & %mask2 != 0, we must have %s <= %t.
For example if %mask1 = 24 and %mask2 = 16, setting %s = 16 and %t = 8
violates condition (2) above. So this optimization cannot be applied.
llvm-svn: 289813
After r289755, the AssumptionCache is no longer needed. Variables affected by
assumptions are now found by using the new operand-bundle-based scheme. This
new scheme is more computationally efficient, and also we need much less
code...
llvm-svn: 289756
This is prep work before changing the callers to also use APInt which will
allow folds for splat vectors. Currently, the callers have ConstantInt
guards in place, so no functional change intended with this commit.
llvm-svn: 280282
It's much less code and easier to read if we don't duplicate
everything between the 'Inside' and not 'Inside' cases.
As noted with the FIXME, the goal is to make this vector-friendly
in a follow-up patch.
llvm-svn: 280183
Summary:
InstCombine unfolds expressions of the form `zext(or(icmp, icmp))` to `or(zext(icmp), zext(icmp))` such that in a later iteration of InstCombine the exposed `zext(icmp)` instructions can be optimized. We now combine this unfolding and the subsequent `zext(icmp)` optimization to be performed together. Since the unfolding doesn't happen separately anymore, we also again enable the folding of `logic(cast(icmp), cast(icmp))` expressions to `cast(logic(icmp, icmp))` which had been disabled due to its interference with the unfolding transformation.
Tested via `make check` and `lnt`.
Background
==========
For a better understanding on how it came to this change we subsequently summarize its history. In commit r275989 we've already tried to enable the folding of `logic(cast(icmp), cast(icmp))` to `cast(logic(icmp, icmp))` which had to be reverted in r276106 because it could lead to an endless loop in InstCombine (also see http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160718/374347.html). The root of this problem is that in `visitZExt()` in InstCombineCasts.cpp there also exists a reverse of the above folding transformation, that unfolds `zext(or(icmp, icmp))` to `or(zext(icmp), zext(icmp))` in order to expose `zext(icmp)` operations which would then possibly be eliminated by subsequent iterations of InstCombine. However, before these `zext(icmp)` would be eliminated the folding from r275989 could kick in and cause InstCombine to endlessly switch back and forth between the folding and the unfolding transformation. This is the reason why we now combine the `zext`-unfolding and the elimination of the exposed `zext(icmp)` to happen at one go because this enables us to still allow the cast-folding in `logic(cast(icmp), cast(icmp))` without entering an endless loop again.
Details on the submitted changes
================================
- In `visitZExt()` we combine the unfolding and optimization of `zext` instructions.
- In `transformZExtICmp()` we have to use `Builder->CreateIntCast()` instead of `CastInst::CreateIntegerCast()` to make sure that the new `CastInst` is inserted in a `BasicBlock`. The new calls to `transformZExtICmp()` that we introduce in `visitZExt()` would otherwise cause according assertions to be triggered (in our case this happend, for example, with lnt for the MultiSource/Applications/sqlite3 and SingleSource/Regression/C++/EH/recursive-throw tests). The subsequent usage of `replaceInstUsesWith()` is necessary to ensure that the new `CastInst` replaces the `ZExtInst` accordingly.
- In InstCombineAndOrXor.cpp we again allow the folding of casts on `icmp` instructions.
- The instruction order in the optimized IR for the zext-or-icmp.ll test case is different with the introduced changes.
- The test cases in zext.ll have been adopted from the reverted commits r275989 and r276105.
Reviewers: grosser, majnemer, spatel
Subscribers: eli.friedman, majnemer, llvm-commits
Differential Revision: https://reviews.llvm.org/D22864
Contributed-by: Matthias Reisinger <d412vv1n@gmail.com>
llvm-svn: 277635
As noted in https://reviews.llvm.org/D22537 , we can use this functionality in
visitSelectInstWithICmp() and InstSimplify, but currently we have duplicated
code.
llvm-svn: 276140
Summary:
Currently, InstCombine is already able to fold expressions of the form `logic(cast(A), cast(B))` to the simpler form `cast(logic(A, B))`, where logic designates one of `and`/`or`/`xor`. This transformation is implemented in `foldCastedBitwiseLogic()` in InstCombineAndOrXor.cpp. However, this optimization will not be performed if both `A` and `B` are `icmp` instructions. The decision to preclude casts of `icmp` instructions originates in r48715 in combination with r261707, and can be best understood by the title of the former one:
> Transform (zext (or (icmp), (icmp))) to (or (zext (cimp), (zext icmp))) if at least one of the (zext icmp) can be transformed to eliminate an icmp.
Apparently, it introduced a transformation that is a reverse of the transformation that is done in `foldCastedBitwiseLogic()`. Its purpose is to expose pairs of `zext icmp` that would subsequently be optimized by `transformZExtICmp()` in InstCombineCasts.cpp. Therefore, in order to avoid an endless loop of switching back and forth between these two transformations, the one in `foldCastedBitwiseLogic()` has been restricted to exclude `icmp` instructions which is mirrored in the responsible check:
`if ((!isa<ICmpInst>(Cast0Src) || !isa<ICmpInst>(Cast1Src)) && ...`
This check seems to sort out more cases than necessary because:
- the reverse transformation is obviously done for `or` instructions only
- and also not every `zext icmp` pair is necessarily the result of this reverse transformation
Therefore we now remove this check and replace it by a more finegrained one in `shouldOptimizeCast()` that now rejects only those `logic(zext(icmp), zext(icmp))` that would be able to be optimized by `transformZExtICmp()`, which also avoids the mentioned endless loop. That means we are now able to also simplify expressions of the form `logic(cast(icmp), cast(icmp))` to `cast(logic(icmp, icmp))` (`cast` being an arbitrary `CastInst`).
As an example, consider the following IR snippet
```
%1 = icmp sgt i64 %a, %b
%2 = zext i1 %1 to i8
%3 = icmp slt i64 %a, %c
%4 = zext i1 %3 to i8
%5 = and i8 %2, %4
```
which would now be transformed to
```
%1 = icmp sgt i64 %a, %b
%2 = icmp slt i64 %a, %c
%3 = and i1 %1, %2
%4 = zext i1 %3 to i8
```
This issue became apparent when experimenting with the programming language Julia, which makes use of LLVM. Currently, Julia lowers its `Bool` datatype to LLVM's `i8` (also see https://github.com/JuliaLang/julia/pull/17225). In fact, the above IR example is the lowered form of the Julia snippet `(a > b) & (a < c)`. Like shown above, this may introduce `zext` operations, casting between `i1` and `i8`, which could for example hinder ScalarEvolution and Polly on certain code.
Reviewers: grosser, vtjnash, majnemer
Subscribers: majnemer, llvm-commits
Differential Revision: https://reviews.llvm.org/D22511
Contributed-by: Matthias Reisinger
llvm-svn: 275989
Summary:
This patch cleans up parts of InstCombine to raise its compliance with the LLVM coding standards and to increase its readability. The changes and according rationale are summarized in the following:
- Rename `ShouldOptimizeCast()` to `shouldOptimizeCast()` since functions should start with a lower case letter.
- Move `shouldOptimizeCast()` from InstCombineCasts.cpp to InstCombineAndOrXor.cpp since it's only used there.
- Simplify interface of `shouldOptimizeCast()`.
- Minor code style adaptions in `shouldOptimizeCast()`.
- Remove the documentation on the function definition of `shouldOptimizeCast()` since it just repeats the documentation on its declaration. Also enhance the documentation on its declaration with more information describing its intended use and make it doxygen-compliant.
- Change a comment in `foldCastedBitwiseLogic()` from `fold (logic (cast A), (cast B)) -> (cast (logic A, B))` to `fold logic(cast(A), cast(B)) -> cast(logic(A, B))` since the surrounding comments use this format.
- Remove comment `Only do this if the casts both really cause code to be generated.` in `foldCastedBitwiseLogic()` since it just repeats parts of the documentation of `shouldOptimizeCast()` and does not help to improve readability.
- Simplify the interface of `isEliminableCastPair()`.
- Removed the documentation on the function definition of `isEliminableCastPair()` which only contained obvious statements about its implementation. Instead added more general doxygen-compliant documentation to its declaration.
- Renamed parameter `DoXform` of `transformZExtIcmp()` to `DoTransform` to make its intention clearer.
- Moved documentation of `transformZExtIcmp()` from its definition to its declaration and made it doxygen-compliant.
Reviewers: vtjnash, grosser
Subscribers: majnemer, llvm-commits
Differential Revision: https://reviews.llvm.org/D22449
Contributed-by: Matthias Reisinger
llvm-svn: 275964
In D21740, we discussed trying to make this a more general matcher. However, I didn't see a clean
way to handle the regular m_Not cases and these non-splat vector patterns, so I've opted for the
direct approach here. If there are other potential uses of areInverseVectorBitmasks(), we could
move that helper function to a higher level.
There is an open question as to which is of these forms should be considered the canonical IR:
%sel = select <4 x i1> <i1 true, i1 false, i1 false, i1 true>, <4 x i32> %a, <4 x i32> %b
%shuf = shufflevector <4 x i32> %a, <4 x i32> %b, <4 x i32> <i32 0, i32 5, i32 6, i32 3>
Differential Revision: http://reviews.llvm.org/D22114
llvm-svn: 275289
This isn't a sure thing (are 2 extra bitcasts less expensive than a logic op?),
but we'll try to err on the conservative side by going with the case that has
less IR instructions.
Note: This question came up in http://reviews.llvm.org/D22114 , but this part is
independent of that patch proposal, so I'm making this small change ahead of that
one.
See also:
http://reviews.llvm.org/rL274926
llvm-svn: 274932
By putting all the possible commutations together, we simplify the code.
Note that this is NFCI, but I'm adding tests that actually exercise each
commutation pattern because we don't have this anywhere else.
llvm-svn: 273702
By moving this transform to InstSimplify from InstCombine, we sidestep the problem/question
raised by PR27869:
https://llvm.org/bugs/show_bug.cgi?id=27869
...where InstCombine turns an icmp+zext into a shift causing us to miss the fold.
Credit to David Majnemer for a draft patch of the changes to InstructionSimplify.cpp.
Differential Revision: http://reviews.llvm.org/D21512
llvm-svn: 273200
There was concern that creating bitcasts for the simpler potential select pattern:
define <2 x i64> @vecBitcastOp1(<4 x i1> %cmp, <2 x i64> %a) {
%a2 = add <2 x i64> %a, %a
%sext = sext <4 x i1> %cmp to <4 x i32>
%bc = bitcast <4 x i32> %sext to <2 x i64>
%and = and <2 x i64> %a2, %bc
ret <2 x i64> %and
}
might lead to worse code for some targets, so this patch is matching the larger
patterns seen in the test cases.
The motivating example for this patch is this IR produced via SSE intrinsics in C:
define <2 x i64> @gibson(<2 x i64> %a, <2 x i64> %b) {
%t0 = bitcast <2 x i64> %a to <4 x i32>
%t1 = bitcast <2 x i64> %b to <4 x i32>
%cmp = icmp sgt <4 x i32> %t0, %t1
%sext = sext <4 x i1> %cmp to <4 x i32>
%t2 = bitcast <4 x i32> %sext to <2 x i64>
%and = and <2 x i64> %t2, %a
%neg = xor <4 x i32> %sext, <i32 -1, i32 -1, i32 -1, i32 -1>
%neg2 = bitcast <4 x i32> %neg to <2 x i64>
%and2 = and <2 x i64> %neg2, %b
%or = or <2 x i64> %and, %and2
ret <2 x i64> %or
}
For an AVX target, this is currently:
vpcmpgtd %xmm1, %xmm0, %xmm2
vpand %xmm0, %xmm2, %xmm0
vpandn %xmm1, %xmm2, %xmm1
vpor %xmm1, %xmm0, %xmm0
retq
With this patch, it becomes:
vpmaxsd %xmm1, %xmm0, %xmm0
Differential Revision: http://reviews.llvm.org/D20774
llvm-svn: 271676
This is effectively NFC because we already do this transform after r175380:
http://reviews.llvm.org/rL175380
and also via foldBoolSextMaskToSelect().
This change should just make it a bit more efficient to match the pattern.
The original guard was added in r95058:
http://reviews.llvm.org/rL95058
A sampling of codegen for current in-tree targets shows no problems. This
makes sense given that we're already producing the vector selects via the
other transforms.
llvm-svn: 271554
Michael Liao