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[InstCombine] Canonicalize insert splat sequences into an insert + shuffle 

This adds a combine that canonicalizes a chain of inserts which broadcasts
a value into a single insert + a splat shufflevector.

This fixes PR31286.

Differential Revision: https://reviews.llvm.org/D27992

llvm-svn: 290641
This commit is contained in:
Michael Kuperstein 2016-12-28 00:18:08 +00:00
parent 2a8440df70
commit cd7ad7130f
6 changed files with 177 additions and 11 deletions
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57
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
View File

@ -593,6 +593,58 @@ static bool isShuffleEquivalentToSelect(ShuffleVectorInst &Shuf) {
return true;
}
// Turn a chain of inserts that splats a value into a canonical insert + shuffle
// splat. That is:
// insertelt(insertelt(insertelt(insertelt X, %k, 0), %k, 1), %k, 2) ... ->
// shufflevector(insertelt(X, %k, 0), undef, zero)
static Instruction *foldInsSequenceIntoBroadcast(InsertElementInst &InsElt) {
// We are interested in the last insert in a chain. So, if this insert
// has a single user, and that user is an insert, bail.
if (InsElt.hasOneUse() && isa<InsertElementInst>(InsElt.user_back()))
return nullptr;
VectorType *VT = cast<VectorType>(InsElt.getType());
int NumElements = VT->getNumElements();
// Do not try to do this for a one-element vector, since that's a nop,
// and will cause an inf-loop.
if (NumElements == 1)
return nullptr;
Value *SplatVal = InsElt.getOperand(1);
InsertElementInst *CurrIE = &InsElt;
SmallVector<bool, 16> ElementPresent(NumElements, false);
// Walk the chain backwards, keeping track of which indices we inserted into,
// until we hit something that isn't an insert of the splatted value.
while (CurrIE) {
ConstantInt *Idx = dyn_cast<ConstantInt>(CurrIE->getOperand(2));
if (!Idx || CurrIE->getOperand(1) != SplatVal)
return nullptr;
// Check none of the intermediate steps have any additional uses.
if ((CurrIE != &InsElt) && !CurrIE->hasOneUse())
return nullptr;
ElementPresent[Idx->getZExtValue()] = true;
CurrIE = dyn_cast<InsertElementInst>(CurrIE->getOperand(0));
}
// Make sure we've seen an insert into every element.
if (llvm::any_of(ElementPresent, [](bool Present) { return !Present; }))
return nullptr;
// All right, create the insert + shuffle.
Instruction *InsertFirst = InsertElementInst::Create(
UndefValue::get(VT), SplatVal,
ConstantInt::get(Type::getInt32Ty(InsElt.getContext()), 0), "", &InsElt);
Constant *ZeroMask = ConstantAggregateZero::get(
VectorType::get(Type::getInt32Ty(InsElt.getContext()), NumElements));
return new ShuffleVectorInst(InsertFirst, UndefValue::get(VT), ZeroMask);
}
/// insertelt (shufflevector X, CVec, Mask|insertelt X, C1, CIndex1), C, CIndex
/// --> shufflevector X, CVec', Mask'
static Instruction *foldConstantInsEltIntoShuffle(InsertElementInst &InsElt) {
@ -754,6 +806,11 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
if (Instruction *Shuf = foldConstantInsEltIntoShuffle(IE))
return Shuf;
// Turn a sequence of inserts that broadcasts a scalar into a single
// insert + shufflevector.
if (Instruction *Broadcast = foldInsSequenceIntoBroadcast(IE))
return Broadcast;
return nullptr;
}

2
llvm/test/Transforms/BBVectorize/X86/loop1.ll
View File

@ -38,7 +38,7 @@ for.body: ; preds = %for.body, %entry
; CHECK-NEXT: insertelement
; CHECK-NEXT: fadd <2 x double>
; CHECK-NEXT: insertelement
; CHECK-NEXT: insertelement
; CHECK-NEXT: shufflevector
; CHECK-NEXT: fadd <2 x double>
; CHECK-NEXT: insertelement
; CHECK-NEXT: fmul <2 x double>

6
llvm/test/Transforms/BBVectorize/loop1.ll
View File

@ -46,10 +46,10 @@ for.body: ; preds = %for.body, %entry
; CHECK: %add4.v.i1.1 = insertelement <2 x double> undef, double %1, i32 0
; CHECK: %add4.v.i1.2 = insertelement <2 x double> %add4.v.i1.1, double %0, i32 1
; CHECK: %add4 = fadd <2 x double> %add4.v.i1.2, %add4.v.i1.2
; CHECK: %add5.v.i1.1 = insertelement <2 x double> undef, double %0, i32 0
; CHECK: %add5.v.i1.2 = insertelement <2 x double> %add5.v.i1.1, double %0, i32 1
; CHECK: %2 = insertelement <2 x double> undef, double %0, i32 0
; CHECK: %add5.v.i1.2 = shufflevector <2 x double> %2, <2 x double> undef, <2 x i32> zeroinitializer
; CHECK: %add5 = fadd <2 x double> %add4, %add5.v.i1.2
; CHECK: %mul6.v.i0.2 = insertelement <2 x double> %add5.v.i1.1, double %mul8, i32 1
; CHECK: %mul6.v.i0.2 = insertelement <2 x double> %2, double %mul8, i32 1
; CHECK: %mul6 = fmul <2 x double> %mul6.v.i0.2, %add5
; CHECK: %mul6.v.r1 = extractelement <2 x double> %mul6, i32 0
; CHECK: %mul6.v.r2 = extractelement <2 x double> %mul6, i32 1

2
llvm/test/Transforms/BBVectorize/simple-int.ll
View File

@ -177,7 +177,7 @@ define double @testcopysign(double %A1, double %A2, double %B1, double %B2) {
; CHECK: %X1.v.i0.1 = insertelement <2 x double> undef, double %A1, i32 0
; CHECK: %X1.v.i0.2 = insertelement <2 x double> %X1.v.i0.1, double %A2, i32 1
; CHECK: %X1 = fsub <2 x double> %X1.v.i0.2, %X1.v.i1.2
; CHECK: %Y1.v.i1.2 = insertelement <2 x double> %X1.v.i0.1, double %A1, i32 1
; CHECK: %Y1.v.i1.2 = shufflevector <2 x double> %X1.v.i0.1, <2 x double> undef, <2 x i32> zeroinitializer
; CHECK: %Y1 = call <2 x double> @llvm.copysign.v2f64(<2 x double> %X1, <2 x double> %Y1.v.i1.2)
; CHECK: %Z1 = fadd <2 x double> %Y1, %X1.v.i1.2
; CHECK: %Z1.v.r1 = extractelement <2 x double> %Z1, i32 0

109
llvm/test/Transforms/InstCombine/broadcast.ll Normal file
View File

@ -0,0 +1,109 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
; CHECK-LABEL: good1
; CHECK: %[[INS:.*]] = insertelement <4 x float> undef, float %arg, i32 0
; CHECK-NEXT: %[[BCAST:.*]] = shufflevector <4 x float> %[[INS]], <4 x float> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: ret <4 x float> %[[BCAST]]
define <4 x float> @good1(float %arg) {
%tmp = insertelement <4 x float> undef, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: good2
; CHECK: %[[INS:.*]] = insertelement <4 x float> undef, float %arg, i32 0
; CHECK-NEXT: %[[BCAST:.*]] = shufflevector <4 x float> %[[INS]], <4 x float> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: ret <4 x float> %[[BCAST]]
define <4 x float> @good2(float %arg) {
%tmp = insertelement <4 x float> undef, float %arg, i32 1
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 2
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 0
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: good3
; CHECK: %[[INS:.*]] = insertelement <4 x float> undef, float %arg, i32 0
; CHECK-NEXT: %[[BCAST:.*]] = shufflevector <4 x float> %[[INS]], <4 x float> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: ret <4 x float> %[[BCAST]]
define <4 x float> @good3(float %arg) {
%tmp = insertelement <4 x float> zeroinitializer, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: good4
; CHECK: %[[INS:.*]] = insertelement <4 x float> undef, float %arg, i32 0
; CHECK-NEXT: %[[ADD:.*]] = fadd <4 x float> %[[INS]], %[[INS]]
; CHECK-NEXT: %[[BCAST:.*]] = shufflevector <4 x float> %[[ADD]], <4 x float> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: ret <4 x float> %[[BCAST]]
define <4 x float> @good4(float %arg) {
%tmp = insertelement <4 x float> zeroinitializer, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
%tmp7 = fadd <4 x float> %tmp6, %tmp6
ret <4 x float> %tmp7
}
; CHECK-LABEL: bad1
; CHECK-NOT: shufflevector
define <4 x float> @bad1(float %arg) {
%tmp = insertelement <4 x float> undef, float %arg, i32 1
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: bad2
; CHECK-NOT: shufflevector
define <4 x float> @bad2(float %arg) {
%tmp = insertelement <4 x float> undef, float %arg, i32 0
%tmp5 = insertelement <4 x float> %tmp, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: bad3
; CHECK-NOT: shufflevector
define <4 x float> @bad3(float %arg, float %arg2) {
%tmp = insertelement <4 x float> undef, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg2, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}
; CHECK-LABEL: bad4
; CHECK-NOT: shufflevector
define <1 x float> @bad4(float %arg) {
%tmp = insertelement <1 x float> undef, float %arg, i32 0
ret <1 x float> %tmp
}
; CHECK-LABEL: bad5
; CHECK-NOT: shufflevector
define <4 x float> @bad5(float %arg) {
%tmp = insertelement <4 x float> undef, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 2
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
%tmp7 = fadd <4 x float> %tmp6, %tmp4
ret <4 x float> %tmp7
}
; CHECK-LABEL: bad6
; CHECK-NOT: shufflevector
define <4 x float> @bad6(float %arg, i32 %k) {
%tmp = insertelement <4 x float> undef, float %arg, i32 0
%tmp4 = insertelement <4 x float> %tmp, float %arg, i32 1
%tmp5 = insertelement <4 x float> %tmp4, float %arg, i32 %k
%tmp6 = insertelement <4 x float> %tmp5, float %arg, i32 3
ret <4 x float> %tmp6
}

12
llvm/test/Transforms/SLPVectorizer/X86/operandorder.ll
View File

@ -26,7 +26,7 @@ define void @shuffle_operands1(double * noalias %from, double * noalias %to,
; CHECK-LABEL: shuffle_preserve_broadcast
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {
@ -51,7 +51,7 @@ ext:
; CHECK-LABEL: shuffle_preserve_broadcast2
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast2(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {
@ -76,7 +76,7 @@ ext:
; CHECK-LABEL: shuffle_preserve_broadcast3
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast3(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {
@ -102,7 +102,7 @@ ext:
; CHECK-LABEL: shuffle_preserve_broadcast4
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast4(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {
@ -127,7 +127,7 @@ ext:
; CHECK-LABEL: shuffle_preserve_broadcast5
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast5(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {
@ -153,7 +153,7 @@ ext:
; CHECK-LABEL: shuffle_preserve_broadcast6
; CHECK: %[[BCAST:[a-z0-9]+]] = insertelement <2 x double> undef, double %v0_1
; CHECK: = insertelement <2 x double> %[[BCAST]], double %v0_1
; CHECK: = shufflevector <2 x double> %[[BCAST]], <2 x double> undef, <2 x i32> zeroinitializer
define void @shuffle_preserve_broadcast6(double * noalias %from,
double * noalias %to,
double %v1, double %v2) {