It's possible for the constant pool entry for the shuffle mask to come
from a completely different operation. This occurs when Constants have
the same bit pattern but have different types.
Make DecodePSHUFBMask tolerant of types which, after a bitcast, are
appropriately sized vector types.
This fixes PR22188.
llvm-svn: 225597
Teach the ISelLowering for X86 about the L,M,O target specific constraints.
Although, for the moment, clang performs constraint validation and prevents
passing along inline asm which may have immediate constant constraints violated,
the backend should be able to cope with the invalid inline asm a bit better.
llvm-svn: 225596
In the current code we only attempt to match against insertps if we have exactly one element from the second input vector, irrespective of how much of the shuffle result is zeroable.
This patch checks to see if there is a single non-zeroable element from either input that requires insertion. It also supports matching of cases where only one of the inputs need to be referenced.
We also split insertps shuffle matching off into a new lowerVectorShuffleAsInsertPS function.
Differential Revision: http://reviews.llvm.org/D6879
llvm-svn: 225589
pshufb can shuffle in zero bytes as well as bytes from a source vector - we can use this to avoid having to shuffle 2 vectors and ORing the result when the used inputs from a vector are all zeroable.
Differential Revision: http://reviews.llvm.org/D6878
llvm-svn: 225551
complements the new vector shuffle lowering code path. This flag,
naturally, is *off* because we've not tested or evaluated the results of
this at all. However, the flag will make it much easier to evaluate
whether we can be this aggressive and whether there are missing vector
shuffle lowering optimizations.
llvm-svn: 225491
The call lowering assumes that if the callee is a global, we want to emit a direct call.
This is correct for regular globals, but not for TLS ones.
Differential Revision: http://reviews.llvm.org/D6862
llvm-svn: 225438
type (in addition to the memory type).
The *LoadExt* legalization handling used to only have one type, the
memory type. This forced users to assume that as long as the extload
for the memory type was declared legal, and the result type was legal,
the whole extload was legal.
However, this isn't always the case. For instance, on X86, with AVX,
this is legal:
v4i32 load, zext from v4i8
but this isn't:
v4i64 load, zext from v4i8
Whereas v4i64 is (arguably) legal, even without AVX2.
Note that the same thing was done a while ago for truncstores (r46140),
but I assume no one needed it yet for extloads, so here we go.
Calls to getLoadExtAction were changed to add the value type, found
manually in the surrounding code.
Calls to setLoadExtAction were mechanically changed, by wrapping the
call in a loop, to match previous behavior. The loop iterates over
the MVT subrange corresponding to the memory type (FP vectors, etc...).
I also pulled neighboring setTruncStoreActions into some of the loops;
those shouldn't make a difference, as the additional types are illegal.
(e.g., i128->i1 truncstores on PPC.)
No functional change intended.
Differential Revision: http://reviews.llvm.org/D6532
llvm-svn: 225421
"ELF Handling for Thread-Local Storage" specifies that R_X86_64_GOTTPOFF
relocation target a movq or addq instruction.
Prohibit the truncation of such loads to movl or addl.
This fixes PR22083.
Differential Revision: http://reviews.llvm.org/D6839
llvm-svn: 225250
The assembler backend will relax to the long form if necessary. This removes a swap from long form to short form in the MCInstLowering code. Selecting the long form used to be required by the old JIT.
llvm-svn: 225242
If the control flow is modelling an if-statement where the only instruction in
the 'then' basic block (excluding the terminator) is a call to cttz/ctlz,
CodeGenPrepare can try to speculate the cttz/ctlz call and simplify the control
flow graph.
Example:
\code
entry:
%cmp = icmp eq i64 %val, 0
br i1 %cmp, label %end.bb, label %then.bb
then.bb:
%c = tail call i64 @llvm.cttz.i64(i64 %val, i1 true)
br label %end.bb
end.bb:
%cond = phi i64 [ %c, %then.bb ], [ 64, %entry]
\code
In this example, basic block %then.bb is taken if value %val is not zero.
Also, the phi node in %end.bb would propagate the size-of in bits of %val
only if %val is equal to zero.
With this patch, CodeGenPrepare will try to hoist the call to cttz from %then.bb
into basic block %entry only if cttz is cheap to speculate for the target.
Added two new hooks in TargetLowering.h to let targets customize the behavior
(i.e. decide whether it is cheap or not to speculate calls to cttz/ctlz). The
two new methods are 'isCheapToSpeculateCtlz' and 'isCheapToSpeculateCttz'.
By default, both methods return 'false'.
On X86, method 'isCheapToSpeculateCtlz' returns true only if the target has
LZCNT. Method 'isCheapToSpeculateCttz' only returns true if the target has BMI.
Differential Revision: http://reviews.llvm.org/D6728
llvm-svn: 224899
When combining consecutive loads+inserts into a single vector load,
we should keep the alignment of the base load. Doing otherwise can, and does,
lead to using overly aligned instructions. In the included test case, for
example, using a 32-byte vmovaps on a 16-byte aligned value. Oops.
rdar://19190968
llvm-svn: 224746
Previously I tried to plug musttail into the existing vararg lowering
code. That turned out to be a mistake, because non-vararg calls use
significantly different register lowering, even on x86. For example, AVX
vectors are usually passed in registers to normal functions and memory
to vararg functions. Now musttail uses a completely separate lowering.
Hopefully this can be used as the basis for non-x86 perfect forwarding.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D6156
llvm-svn: 224745
Currently, when ctpop is supported for scalar types, the expansion of
@llvm.ctpop.vXiY uses vector element extractions, insertions and individual
calls to @llvm.ctpop.iY. When not, expansion with bit-math operations is used
for the scalar calls.
Local haswell measurements show that we can improve vector @llvm.ctpop.vXiY
expansion in some cases by using a using a vector parallel bit twiddling
approach, based on:
v = v - ((v >> 1) & 0x55555555);
v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
v = ((v + (v >> 4) & 0xF0F0F0F)
v = v + (v >> 8)
v = v + (v >> 16)
v = v & 0x0000003F
(from http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel)
When scalar ctpop isn't supported, the approach above performs better for
v2i64, v4i32, v4i64 and v8i32 (see numbers below). And even when scalar ctpop
is supported, this approach performs ~2x better for v8i32.
Here, x86_64 implies -march=corei7-avx without ctpop and x86_64h includes ctpop
support with -march=core-avx2.
== [x86_64h - new]
v8i32: 0.661685
v4i32: 0.514678
v4i64: 0.652009
v2i64: 0.324289
== [x86_64h - old]
v8i32: 1.29578
v4i32: 0.528807
v4i64: 0.65981
v2i64: 0.330707
== [x86_64 - new]
v8i32: 1.003
v4i32: 0.656273
v4i64: 1.11711
v2i64: 0.754064
== [x86_64 - old]
v8i32: 2.34886
v4i32: 1.72053
v4i64: 1.41086
v2i64: 1.0244
More work for other vector types will come next.
llvm-svn: 224725
Added RegOp2MemOpTable4 to transform 4th operand from register to memory in merge-masked versions of instructions.
Added lowering tests.
llvm-svn: 224516
This handles the case of a BUILD_VECTOR being constructed out of elements extracted from a vector twice the size of the result vector. Previously this was always scalarized. Now, we try to construct a shuffle node that feeds on extract_subvectors.
This fixes PR15872 and provides a partial fix for PR21711.
Differential Revision: http://reviews.llvm.org/D6678
llvm-svn: 224429
The type promotion helper does not support vector type, so when make
such it does not kick in in such cases.
Original commit message:
[CodeGenPrepare] Move sign/zero extensions near loads using type promotion.
This patch extends the optimization in CodeGenPrepare that moves a sign/zero
extension near a load when the target can combine them. The optimization may
promote any operations between the extension and the load to make that possible.
Although this optimization may be beneficial for all targets, in particular
AArch64, this is enabled for X86 only as I have not benchmarked it for other
targets yet.
** Context **
Most targets feature extended loads, i.e., loads that perform a zero or sign
extension for free. In that context it is interesting to expose such pattern in
CodeGenPrepare so that the instruction selection pass can form such loads.
Sometimes, this pattern is blocked because of instructions between the load and
the extension. When those instructions are promotable to the extended type, we
can expose this pattern.
** Motivating Example **
Let us consider an example:
define void @foo(i8* %addr1, i32* %addr2, i8 %a, i32 %b) {
%ld = load i8* %addr1
%zextld = zext i8 %ld to i32
%ld2 = load i32* %addr2
%add = add nsw i32 %ld2, %zextld
%sextadd = sext i32 %add to i64
%zexta = zext i8 %a to i32
%addza = add nsw i32 %zexta, %zextld
%sextaddza = sext i32 %addza to i64
%addb = add nsw i32 %b, %zextld
%sextaddb = sext i32 %addb to i64
call void @dummy(i64 %sextadd, i64 %sextaddza, i64 %sextaddb)
ret void
}
As it is, this IR generates the following assembly on x86_64:
[...]
movzbl (%rdi), %eax # zero-extended load
movl (%rsi), %es # plain load
addl %eax, %esi # 32-bit add
movslq %esi, %rdi # sign extend the result of add
movzbl %dl, %edx # zero extend the first argument
addl %eax, %edx # 32-bit add
movslq %edx, %rsi # sign extend the result of add
addl %eax, %ecx # 32-bit add
movslq %ecx, %rdx # sign extend the result of add
[...]
The throughput of this sequence is 7.45 cycles on Ivy Bridge according to IACA.
Now, by promoting the additions to form more extended loads we would generate:
[...]
movzbl (%rdi), %eax # zero-extended load
movslq (%rsi), %rdi # sign-extended load
addq %rax, %rdi # 64-bit add
movzbl %dl, %esi # zero extend the first argument
addq %rax, %rsi # 64-bit add
movslq %ecx, %rdx # sign extend the second argument
addq %rax, %rdx # 64-bit add
[...]
The throughput of this sequence is 6.15 cycles on Ivy Bridge according to IACA.
This kind of sequences happen a lot on code using 32-bit indexes on 64-bit
architectures.
Note: The throughput numbers are similar on Sandy Bridge and Haswell.
** Proposed Solution **
To avoid the penalty of all these sign/zero extensions, we merge them in the
loads at the beginning of the chain of computation by promoting all the chain of
computation on the extended type. The promotion is done if and only if we do not
introduce new extensions, i.e., if we do not degrade the code quality.
To achieve this, we extend the existing “move ext to load” optimization with the
promotion mechanism introduced to match larger patterns for addressing mode
(r200947).
The idea of this extension is to perform the following transformation:
ext(promotableInst1(...(promotableInstN(load))))
=>
promotedInst1(...(promotedInstN(ext(load))))
The promotion mechanism in that optimization is enabled by a new TargetLowering
switch, which is off by default. In other words, by default, the optimization
performs the “move ext to load” optimization as it was before this patch.
** Performance **
Configuration: x86_64: Ivy Bridge fixed at 2900MHz running OS X 10.10.
Tested Optimization Levels: O3/Os
Tests: llvm-testsuite + externals.
Results:
- No regression beside noise.
- Improvements:
CINT2006/473.astar: ~2%
Benchmarks/PAQ8p: ~2%
Misc/perlin: ~3%
The results are consistent for both O3 and Os.
<rdar://problem/18310086>
llvm-svn: 224402
This patch extends the optimization in CodeGenPrepare that moves a sign/zero
extension near a load when the target can combine them. The optimization may
promote any operations between the extension and the load to make that possible.
Although this optimization may be beneficial for all targets, in particular
AArch64, this is enabled for X86 only as I have not benchmarked it for other
targets yet.
** Context **
Most targets feature extended loads, i.e., loads that perform a zero or sign
extension for free. In that context it is interesting to expose such pattern in
CodeGenPrepare so that the instruction selection pass can form such loads.
Sometimes, this pattern is blocked because of instructions between the load and
the extension. When those instructions are promotable to the extended type, we
can expose this pattern.
** Motivating Example **
Let us consider an example:
define void @foo(i8* %addr1, i32* %addr2, i8 %a, i32 %b) {
%ld = load i8* %addr1
%zextld = zext i8 %ld to i32
%ld2 = load i32* %addr2
%add = add nsw i32 %ld2, %zextld
%sextadd = sext i32 %add to i64
%zexta = zext i8 %a to i32
%addza = add nsw i32 %zexta, %zextld
%sextaddza = sext i32 %addza to i64
%addb = add nsw i32 %b, %zextld
%sextaddb = sext i32 %addb to i64
call void @dummy(i64 %sextadd, i64 %sextaddza, i64 %sextaddb)
ret void
}
As it is, this IR generates the following assembly on x86_64:
[...]
movzbl (%rdi), %eax # zero-extended load
movl (%rsi), %es # plain load
addl %eax, %esi # 32-bit add
movslq %esi, %rdi # sign extend the result of add
movzbl %dl, %edx # zero extend the first argument
addl %eax, %edx # 32-bit add
movslq %edx, %rsi # sign extend the result of add
addl %eax, %ecx # 32-bit add
movslq %ecx, %rdx # sign extend the result of add
[...]
The throughput of this sequence is 7.45 cycles on Ivy Bridge according to IACA.
Now, by promoting the additions to form more extended loads we would generate:
[...]
movzbl (%rdi), %eax # zero-extended load
movslq (%rsi), %rdi # sign-extended load
addq %rax, %rdi # 64-bit add
movzbl %dl, %esi # zero extend the first argument
addq %rax, %rsi # 64-bit add
movslq %ecx, %rdx # sign extend the second argument
addq %rax, %rdx # 64-bit add
[...]
The throughput of this sequence is 6.15 cycles on Ivy Bridge according to IACA.
This kind of sequences happen a lot on code using 32-bit indexes on 64-bit
architectures.
Note: The throughput numbers are similar on Sandy Bridge and Haswell.
** Proposed Solution **
To avoid the penalty of all these sign/zero extensions, we merge them in the
loads at the beginning of the chain of computation by promoting all the chain of
computation on the extended type. The promotion is done if and only if we do not
introduce new extensions, i.e., if we do not degrade the code quality.
To achieve this, we extend the existing “move ext to load” optimization with the
promotion mechanism introduced to match larger patterns for addressing mode
(r200947).
The idea of this extension is to perform the following transformation:
ext(promotableInst1(...(promotableInstN(load))))
=>
promotedInst1(...(promotedInstN(ext(load))))
The promotion mechanism in that optimization is enabled by a new TargetLowering
switch, which is off by default. In other words, by default, the optimization
performs the “move ext to load” optimization as it was before this patch.
** Performance **
Configuration: x86_64: Ivy Bridge fixed at 2900MHz running OS X 10.10.
Tested Optimization Levels: O3/Os
Tests: llvm-testsuite + externals.
Results:
- No regression beside noise.
- Improvements:
CINT2006/473.astar: ~2%
Benchmarks/PAQ8p: ~2%
Misc/perlin: ~3%
The results are consistent for both O3 and Os.
<rdar://problem/18310086>
llvm-svn: 224351
EltsFromConsecutiveLoads was apparently only ever called for 128-bit vectors, and assumed this implicitly. r223518 started calling it for AVX-sized vectors, causing the code path that had this assumption to crash.
This adds a check to make this path fire only for 128-bit vectors.
Differential Revision: http://reviews.llvm.org/D6579
llvm-svn: 223922
Before this patch, the backend sub-optimally expanded the non-constant shift
count of a v8i16 shift into a sequence of two 'movd' plus 'movzwl'.
With this patch the backend checks if the target features sse4.1. If so, then
it lets the shuffle legalizer deal with the expansion of the shift amount.
Example:
;;
define <8 x i16> @test(<8 x i16> %A, <8 x i16> %B) {
%shamt = shufflevector <8 x i16> %B, <8 x i16> undef, <8 x i32> zeroinitializer
%shl = shl <8 x i16> %A, %shamt
ret <8 x i16> %shl
}
;;
Before (with -mattr=+avx):
vmovd %xmm1, %eax
movzwl %ax, %eax
vmovd %eax, %xmm1
vpsllw %xmm1, %xmm0, %xmm0
retq
Now:
vpxor %xmm2, %xmm2, %xmm2
vpblendw $1, %xmm1, %xmm2, %xmm1
vpsllw %xmm1, %xmm0, %xmm0
retq
llvm-svn: 223660
X86ISelLowering.cpp has a long switch for intrinsics. I moved a part of
this long switch to the new intrinsics table in X86IntrinsicsInfo.h.
No functional changes, just code and compile time optimization.
llvm-svn: 223641
Fix the poor codegen seen in PR21710 ( http://llvm.org/bugs/show_bug.cgi?id=21710 ).
Before we crack 32-byte build vectors into smaller chunks (and then subsequently
glue them back together), we should look for the easy case where we can just load
all elements in a single op.
An example of the codegen change is:
From:
vmovss 16(%rdi), %xmm1
vmovups (%rdi), %xmm0
vinsertps $16, 20(%rdi), %xmm1, %xmm1
vinsertps $32, 24(%rdi), %xmm1, %xmm1
vinsertps $48, 28(%rdi), %xmm1, %xmm1
vinsertf128 $1, %xmm1, %ymm0, %ymm0
retq
To:
vmovups (%rdi), %ymm0
retq
Differential Revision: http://reviews.llvm.org/D6536
llvm-svn: 223518
Summary:
Follow up to [x32] "Use ebp/esp as frame and stack pointer":
http://reviews.llvm.org/D4617
In that earlier patch, NaCl64 was made to always use rbp.
That's needed for most cases because rbp should hold a full
64-bit address within the NaCl sandbox so that load/stores
off of rbp don't require sandbox adjustment (zeroing the top
32-bits, then filling those by adding r15).
However, llvm.frameaddress returns a pointer and pointers
are 32-bit for NaCl64. In this case, use ebp instead, which
will make the register copy type check. A similar mechanism
may be needed for llvm.eh.return, but is not added in this change.
Test Plan: test/CodeGen/X86/frameaddr.ll
Reviewers: dschuff, nadav
Subscribers: jfb, llvm-commits
Differential Revision: http://reviews.llvm.org/D6514
llvm-svn: 223510
SSE2/AVX non-constant packed shift instructions only use the lower 64-bit of
the shift count.
This patch teaches function 'getTargetVShiftNode' how to deal with shifts
where the shift count node is of type MVT::i64.
Before this patch, function 'getTargetVShiftNode' only knew how to deal with
shift count nodes of type MVT::i32. This forced the backend to wrongly
truncate the shift count to MVT::i32, and then zero-extend it back to MVT::i64.
llvm-svn: 223505
When lowering a vector shift node, the backend checks if the shift count is a
shuffle with a splat mask. If so, then it introduces an extra dag node to
extract the splat value from the shuffle. The splat value is then used
to generate a shift count of a target specific shift.
However, if we know that the shift count is a splat shuffle, we can use the
splat index 'I' to extract the I-th element from the first shuffle operand.
The advantage is that the splat shuffle may become dead since we no longer
use it.
Example:
;;
define <4 x i32> @example(<4 x i32> %a, <4 x i32> %b) {
%c = shufflevector <4 x i32> %b, <4 x i32> undef, <4 x i32> zeroinitializer
%shl = shl <4 x i32> %a, %c
ret <4 x i32> %shl
}
;;
Before this patch, llc generated the following code (-mattr=+avx):
vpshufd $0, %xmm1, %xmm1 # xmm1 = xmm1[0,0,0,0]
vpxor %xmm2, %xmm2
vpblendw $3, %xmm1, %xmm2, %xmm1 # xmm1 = xmm1[0,1],xmm2[2,3,4,5,6,7]
vpslld %xmm1, %xmm0, %xmm0
retq
With this patch, the redundant splat operation is removed from the code.
vpxor %xmm2, %xmm2
vpblendw $3, %xmm1, %xmm2, %xmm1 # xmm1 = xmm1[0,1],xmm2[2,3,4,5,6,7]
vpslld %xmm1, %xmm0, %xmm0
retq
llvm-svn: 223461
David Majnemer