Refactored so that a LSRUse owns its fixups, as oppsed to letting the
LSRInstance own them. This makes it easier to rate formulas for
LSRUses, since the fixups are available directly. The Offsets vector
has been removed since it was no longer necessary.
New target hook isFoldableMemAccessOffset(), which is used during formula
rating.
For SystemZ, this is useful to express that loads and stores with
float or vector types with a big/negative offset should be avoided in
loops. Without this, LSR will generate a lot of negative offsets that
would require extra instructions for loading the address.
Updated tests:
test/CodeGen/SystemZ/loop-01.ll
Reviewed by: Quentin Colombet and Ulrich Weigand.
https://reviews.llvm.org/D19152
llvm-svn: 278927
This is a mechanical change of comments in switches like fallthrough,
fall-through, or fall-thru to use the LLVM_FALLTHROUGH macro instead.
llvm-svn: 278902
IndVarSimplify::sinkUnusedInvariants calls
BasicBlock::getFirstInsertionPt on the ExitBlock and moves instructions
before it. This can return end(), so it's not safe to dereference. Add
an iterator-based overload to Instruction::moveBefore to avoid the UB.
llvm-svn: 278886
BasicBlock::Create isn't designed to take iterators (which might be
end()), but pointers (which might be nullptr). Fix the UB that was
converting end() to a BasicBlock* by calling BasicBlock::getNextNode()
in the first place.
llvm-svn: 278883
Summary:
This is part of a serious of patches to evolve ADCE.cpp to support
removing of unnecessary control flow.
This patch changes the data structures to hold liveness information to
support the additional information we will eventually need. In
particular we now have a notion of basic blocks being live because
they contain a live operations. This will eventually feed into control
dependence analysis of which branches are live. We cater to getting
from instructions to associated block information and from blocks to
information about their terminators.
This patch also changes the structure of the main loop of the
algorithm so that it alternates propagating liveness between
instructions and usign control dependence information to mark branches
live.
We force all terminators live for now until we add code to handlinge
removing control flow in a later patch.
No changes to effective behavior with this patch
Previous patches:
D23065 [ADCE] Refactor anticipating new functionality (NFC)
D23102 [ADCE] Refactoring for new functionality (NFC)
Reviewers: nadav, majnemer, mehdi_amini
Subscribers: freik, twoh, llvm-commits
Differential Revision: https://reviews.llvm.org/D23225
llvm-svn: 278807
If a loop is not rotated (for example when optimizing for size), the latch is not the backedge. If we promote an expression to post-inc form, we not only increase register pressure and add a COPY for that IV expression but for all IVs!
Motivating testcase:
void f(float *a, float *b, float *c, int n) {
while (n-- > 0)
*c++ = *a++ + *b++;
}
It's imperative that the pointer increments be located in the latch block and not the header block; if not, we cannot use post-increment loads and stores and we have to keep both the post-inc and pre-inc values around until the end of the latch which bloats register usage.
llvm-svn: 278658
IRCE has the ability to further version pre-loops and post-loops that it
created, but this isn't useful at all. This change teaches IRCE to
leave behind some metadata in the loops it creates (by cloning the main
loop) so that these new loops are not re-processed by IRCE.
Today this bug is hidden by another bug -- IRCE does not update LoopInfo
properly so the loop pass manager does not re-invoke IRCE on the loops
it split out. However, once the latter is fixed the bug addressed in
this change causes IRCE to infinite-loop in some cases (e.g. it splits
out a pre-loop, a pre-pre-loop from that, a pre-pre-pre-loop from that
and so on).
llvm-svn: 278617
Loops containing `indirectbr` may not be in simplified form, even after
running LoopSimplify. Reject then gracefully, instead of tripping an
assert.
llvm-svn: 278611
Summary:
Refactor the existing support into a LoopDataPrefetch implementation
class and a LoopDataPrefetchLegacyPass class that invokes it.
Add a new LoopDataPrefetchPass for the new pass manager that utilizes
the LoopDataPrefetch implementation class.
Reviewers: mehdi_amini
Subscribers: sanjoy, mzolotukhin, nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D23483
llvm-svn: 278591
`IVVisitor::visitCast` used to have the invariant that if the
instruction it was passed was a sext or zext instruction, the result of
the instruction would be wider than the induction variable. This is no
longer true after rL275037, so this change teaches `IndVarSimplify` s
implementation of `IVVisitor::visitCast` to work with the relaxed
invariant.
A corresponding change to SimplifyIndVar to preserve the said invariant
after rL275037 would also work, but given how `IVVisitor::visitCast` is
spelled (no indication of said invariant), I figured the current fix is
cleaner.
Fixes PR28935.
llvm-svn: 278584
When legal, extending trip count in the loop control logic generates better code compared to truncating IV. This is because
(1) extending trip count is a loop invariant operation (see genLoopLimit where we prove trip count is loop invariant).
(2) Scalar Evolution seems to have problems understanding trunc when computing loop trip count. So removing them allows better analysis performed in Scalar Evolution. (In particular this fixes PR 28363 which is the motivation for this change).
I am not going to perform any performance test. Any degradation caused by this should be an indication of a bug elsewhere.
To prove legality, we rely on SCEV to prove zext(trunc(IV)) == IV (or similarly for sext). If this holds, we can prove equivalence of trunc(IV)==ExitCnt (1) and IV == zext(ExitCnt). Simply take zext of boths sides of (1) and apply the proven equivalence.
This commit contains changes in a newly added testcase which was not included in the previous commit (which was reverted later on).
https://reviews.llvm.org/D23075
llvm-svn: 278421
Summary:
This is an extension of the fix in r271424. That fix dealt with builder
insert points being moved by SCEV expansion, but only for the lifetime
of the expand call. This change modifies the interface so that LSR can
safely call expand multiple times at the same insert point and do the
right thing if one of the expansions decides to move the original insert
point.
This is a fix for PR28719.
Reviewers: sanjoy
Subscribers: llvm-commits, mcrosier, mzolotukhin
Differential Revision: https://reviews.llvm.org/D23342
llvm-svn: 278413
Summary:
This fixes PR 28933 by making sure GVNHoist does not try to recreate memory
accesses when it has not actually moved them.
Reviewers: sebpop
Subscribers: llvm-commits, george.burgess.iv
Differential Revision: https://reviews.llvm.org/D23411
llvm-svn: 278401
When legal, extending trip count in the loop control logic generates better code compared to truncating IV. This is because
(1) extending trip count is a loop invariant operation (see genLoopLimit where we prove trip count is loop invariant).
(2) Scalar Evolution seems to have problems understanding trunc when computing loop trip count. So removing them allows better analysis performed in Scalar Evolution. (In particular this fixes PR 28363 which is the motivation for this change).
I am not going to perform any performance test. Any degradation caused by this should be an indication of a bug elsewhere.
To prove legality, we rely on SCEV to prove zext(trunc(IV)) == IV (or similarly for sext). If this holds, we can prove equivalence of trunc(IV)==ExitCnt (1) and IV == zext(ExitCnt). Simply take zext of boths sides of (1) and apply the proven equivalence.
https://reviews.llvm.org/D23075
llvm-svn: 278334
This is a resubmission of previously reverted r277592. It was hitting overly strong assertion in getConstantRange which was relaxed in r278217.
Use LVI to prove that adds do not wrap. The change is motivated by https://llvm.org/bugs/show_bug.cgi?id=28620 bug and it's the first step to fix that problem.
Reviewed By: sanjoy
Differential Revision: http://reviews.llvm.org/D23059
llvm-svn: 278220
The patch is to fix the bug in PR28705. It was caused by setting wrong return
value for SCEVExpander::findExistingExpansion. The return values of findExistingExpansion
have different meanings when the function is used in different ways so it is easy to make
mistake. The fix creates two new interfaces to replace SCEVExpander::findExistingExpansion,
and specifies where each interface is expected to be used.
Differential Revision: https://reviews.llvm.org/D22942
llvm-svn: 278161
One exception here is LoopInfo which must forward-declare it (because
the typedef is in LoopPassManager.h which depends on LoopInfo).
Also, some includes for LoopPassManager.h were needed since that file
provides the typedef.
Besides a general consistently benefit, the extra layer of indirection
allows the mechanical part of https://reviews.llvm.org/D23256 that
requires touching every transformation and analysis to be factored out
cleanly.
Thanks to David for the suggestion.
llvm-svn: 278079
Besides a general consistently benefit, the extra layer of indirection
allows the mechanical part of https://reviews.llvm.org/D23256 that
requires touching every transformation and analysis to be factored out
cleanly.
Thanks to David for the suggestion.
llvm-svn: 278078
Besides a general consistently benefit, the extra layer of indirection
allows the mechanical part of https://reviews.llvm.org/D23256 that
requires touching every transformation and analysis to be factored out
cleanly.
Thanks to David for the suggestion.
llvm-svn: 278077
Summary:
The correctness fix here is that when we CSE a load with another load,
we need to combine the metadata on the two loads. This matches the
behavior of other passes, like instcombine and GVN.
There's also a minor optimization improvement here: for load PRE, the
aliasing metadata on the inserted load should be the same as the
metadata on the original load. Not sure why the old code was throwing
it away.
Issue found by inspection.
Differential Revision: http://reviews.llvm.org/D21460
llvm-svn: 277977
Fixes PR28764. Right now there is no way to test this, but (as
mentioned on the PR) with Michael Zolotukhin's yet to be checked in
LoopSimplify verfier, 8 of the llvm-lit tests for IRCE crash.
llvm-svn: 277891
Summary:
This is another refactoring to break up the one function into three logical components functions.
Another non-functional change before we start added in features.
Reviewers: nadav, mehdi_amini, majnemer
Subscribers: twoh, freik, llvm-commits
Differential Revision: https://reviews.llvm.org/D23102
llvm-svn: 277855
The patch splits a complex && if condition into easier to read and understand
logic. That wrong early exit condition was letting some instructions with not
all operands available pass through when HoistingGeps was true.
Differential Revision: https://reviews.llvm.org/D23174
llvm-svn: 277785
Limit the number of times the while(1) loop is executed. With this restriction
the number of hoisted instructions does not change in a significant way on the
test-suite.
Differential Revision: https://reviews.llvm.org/D23028
llvm-svn: 277651
With this patch we compute the DFS numbers of instructions only once and update
them during the code generation when an instruction gets hoisted.
Differential Revision: https://reviews.llvm.org/D23021
llvm-svn: 277650
With this patch we compute the MemorySSA once and update it in the code generator.
Differential Revision: https://reviews.llvm.org/D22966
llvm-svn: 277649
Summary:
This is the first refactoring before adding new functionality.
Add a class wrapper for the functions and container for
state associated with the transformation.
No functional change
Reviewers: majnemer, nadav, mehdi_amini
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23065
llvm-svn: 277565
LoopUnroll is a loop pass, so the analysis of OptimizationRemarkEmitter
is added to the common function analysis passes that loop passes
depend on.
The BFI and indirectly BPI used in this pass is computed lazily so no
overhead should be observed unless -pass-remarks-with-hotness is used.
This is how the patch affects the O3 pipeline:
Dominator Tree Construction
Natural Loop Information
Canonicalize natural loops
Loop-Closed SSA Form Pass
Basic Alias Analysis (stateless AA impl)
Function Alias Analysis Results
Scalar Evolution Analysis
+ Lazy Branch Probability Analysis
+ Lazy Block Frequency Analysis
+ Optimization Remark Emitter
Loop Pass Manager
Rotate Loops
Loop Invariant Code Motion
Unswitch loops
Simplify the CFG
Dominator Tree Construction
Basic Alias Analysis (stateless AA impl)
Function Alias Analysis Results
Combine redundant instructions
Natural Loop Information
Canonicalize natural loops
Loop-Closed SSA Form Pass
Scalar Evolution Analysis
+ Lazy Branch Probability Analysis
+ Lazy Block Frequency Analysis
+ Optimization Remark Emitter
Loop Pass Manager
Induction Variable Simplification
Recognize loop idioms
Delete dead loops
Unroll loops
...
llvm-svn: 277203
Some instructions may have their uses replaced with a symbolic constant.
However, the instruction may still have side effects which percludes it
from being removed from the function. EarlyCSE treated such an
instruction as if it were removed, resulting in PR28763.
llvm-svn: 277114
A ConstantVector can have ConstantExpr operands and vice versa.
However, the folder had no ability to fold ConstantVectors which, in
some cases, was an optimization barrier.
Instead, rephrase the folder in terms of Constants instead of
ConstantExprs and teach callers how to deal with failure.
llvm-svn: 277099
Summary: The MadeChange flag should be ORed to keep the previous result.
Reviewers: mcrosier
Subscribers: mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D22873
llvm-svn: 276894
When loading or storing in a field of a struct like "a.b.c", GVN is able to
detect the equivalent expressions, and GVN-hoist would fail in the code
generation. This is because the GEPs are not hoisted as scalar operations to
avoid moving the GEPs too far from their ld/st instruction when the ld/st is not
movable. So we end up having to generate code for the GEP of a ld/st when we
move the ld/st. In the case of a GEP referring to another GEP as in "a.b.c" we
need to code generate all the GEPs necessary to make all the operands available
at the new location for the ld/st. With this patch we recursively walk through
the GEP operands checking whether all operands are available, and in the case of
a GEP operand, it recursively makes all its operands available. Code generation
happens from the inner GEPs out until reaching the GEP that appears as an
operand of the ld/st.
Differential Revision: https://reviews.llvm.org/D22599
llvm-svn: 276841
The patch replaces a function that walks the IR with a call to firstInBB() that
uses the DFS numbering. NFC.
Differential Revision: https://reviews.llvm.org/D22809
llvm-svn: 276840
Instead of DFS numbering basic blocks we now DFS number instructions that avoids
the costly operation of which instruction comes first in a basic block.
Patch mostly written by Daniel Berlin.
Differential Revision: https://reviews.llvm.org/D22777
llvm-svn: 276714
This patch adds an option to specify the maximum depth in a BB at which to
consider hoisting instructions. Hoisting instructions from a deeper level is
not profitable as it increases register pressure and compilation time.
Differential Revision: https://reviews.llvm.org/D22772
llvm-svn: 276713
If we two loads of two different alignments, we must use the minimum of
the two alignments when hoisting. Same deal for stores.
For allocas, use the maximum of the two allocas.
llvm-svn: 276601
Allowed loop vectorization with secondary FP IVs. Like this:
float *A;
float x = init;
for (int i=0; i < N; ++i) {
A[i] = x;
x -= fp_inc;
}
The auto-vectorization is possible when the induction binary operator is "fast" or the function has "unsafe" attribute.
Differential Revision: https://reviews.llvm.org/D21330
llvm-svn: 276554
Recommiting r275571 after fixing crash reported in PR28270.
Now we erase elements of IOL in deleteDeadInstruction().
Original Summary:
This change use the overlap interval map built from partial overwrite tracking to perform shortening MemIntrinsics.
Add test cases which was missing opportunities before.
llvm-svn: 276452
Just because we can constant fold the result of an instruction does not
imply that we can delete the instruction. It may have side effects.
This fixes PR28655.
llvm-svn: 276389
If `-irce-skip-profitability-checks` is passed in, IRCE will kick in in
all cases where it is legal for it to kick in. This flag is intended to
help diagnose and analyse performance issues.
llvm-svn: 276372
Do not clone stored values unless they are GEPs that are special cased to avoid
hoisting them without hoisting their associated ld/st.
Differential revision: https://reviews.llvm.org/D22652
llvm-svn: 276358
We can replace the return values with undef if we replaced all
the call uses with a constant/undef.
Differential Revision: https://reviews.llvm.org/D22336
llvm-svn: 276174
We just set PreserveLCSSA to always true since we don't have an
analogous method `mustPreserveAnalysisID(LCSSA)`.
Also port LoopInfo verifier pass to test LoopUnrollPass.
llvm-svn: 276063
Davide Italiano