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[InstCombine] allow more binop (shuffle X), C transforms 

The canonicalization was restricted to shuffle masks with
a 1-to-1 mapping to the constant vector, but that disqualifies
the common splat pattern. This is part of solving PR37463:
https://bugs.llvm.org/show_bug.cgi?id=37463

llvm-svn: 332479
This commit is contained in:
Sanjay Patel 2018-05-16 15:15:22 +00:00
parent 561228b2fa
commit 2eb3512090
2 changed files with 23 additions and 8 deletions
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6
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -1401,7 +1401,8 @@ Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
// Find constant NewC that has property:
// shuffle(NewC, ShMask) = C
// If such constant does not exist (example: ShMask=<0,0> and C=<1,2>)
// reorder is not possible.
// reorder is not possible. A 1-to-1 mapping is not required. Example:
// ShMask = <1,1,2,2> and C = <5,5,6,6> --> NewC = <undef,5,6,undef>
SmallVector<int, 16> ShMask;
ShuffleVectorInst::getShuffleMask(Mask, ShMask);
SmallVector<Constant *, 16>
@ -1411,7 +1412,8 @@ Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
if (ShMask[I] >= 0) {
assert(ShMask[I] < (int)VWidth);
Constant *CElt = C->getAggregateElement(I);
if (!CElt || !isa<UndefValue>(NewVecC[ShMask[I]])) {
Constant *NewCElt = NewVecC[ShMask[I]];
if (!CElt || (!isa<UndefValue>(NewCElt) && NewCElt != CElt)) {
MayChange = false;
break;
}

25
llvm/test/Transforms/InstCombine/vec_shuffle.ll
View File

@ -439,9 +439,9 @@ define <2 x float> @fadd_const_multiuse(<2 x float> %v) {
define <4 x i32> @mul_const_splat(<4 x i32> %v) {
; CHECK-LABEL: @mul_const_splat(
; CHECK-NEXT: [[T1:%.*]] = shufflevector <4 x i32> [[V:%.*]], <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
; CHECK-NEXT: [[R:%.*]] = mul <4 x i32> [[T1]], <i32 42, i32 42, i32 42, i32 42>
; CHECK-NEXT: ret <4 x i32> [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = mul <4 x i32> [[V:%.*]], <i32 undef, i32 42, i32 undef, i32 undef>
; CHECK-NEXT: [[TMP2:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
; CHECK-NEXT: ret <4 x i32> [[TMP2]]
;
%t1 = shufflevector <4 x i32> %v, <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 1, i32 1>
%r = mul <4 x i32> <i32 42, i32 42, i32 42, i32 42>, %t1
@ -452,15 +452,28 @@ define <4 x i32> @mul_const_splat(<4 x i32> %v) {
define <4 x i32> @lshr_const_half_splat(<4 x i32> %v) {
; CHECK-LABEL: @lshr_const_half_splat(
; CHECK-NEXT: [[T1:%.*]] = shufflevector <4 x i32> [[V:%.*]], <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 2, i32 2>
; CHECK-NEXT: [[R:%.*]] = lshr <4 x i32> <i32 8, i32 8, i32 9, i32 9>, [[T1]]
; CHECK-NEXT: ret <4 x i32> [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = lshr <4 x i32> <i32 undef, i32 8, i32 9, i32 undef>, [[V:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 2, i32 2>
; CHECK-NEXT: ret <4 x i32> [[TMP2]]
;
%t1 = shufflevector <4 x i32> %v, <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 2, i32 2>
%r = lshr <4 x i32> <i32 8, i32 8, i32 9, i32 9>, %t1
ret <4 x i32> %r
}
; We can't change this because there's no pre-shuffle version of the fmul constant.
define <2 x float> @fmul_const_invalid_constant(<2 x float> %v) {
; CHECK-LABEL: @fmul_const_invalid_constant(
; CHECK-NEXT: [[T1:%.*]] = shufflevector <2 x float> [[V:%.*]], <2 x float> undef, <2 x i32> zeroinitializer
; CHECK-NEXT: [[R:%.*]] = fmul <2 x float> [[T1]], <float 4.100000e+01, float 4.200000e+01>
; CHECK-NEXT: ret <2 x float> [[R]]
;
%t1 = shufflevector <2 x float> %v, <2 x float> undef, <2 x i32> <i32 0, i32 0>
%r = fmul <2 x float> %t1, <float 41.0, float 42.0>
ret <2 x float> %r
}
define <4 x i32> @shuffle_17add2(<4 x i32> %v) {
; CHECK-LABEL: @shuffle_17add2(
; CHECK-NEXT: [[TMP1:%.*]] = shl <4 x i32> [[V:%.*]], <i32 1, i32 1, i32 1, i32 1>