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[InstSimplify] fold rotate of -1 to -1

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This is part of solving more general rotate patterns seen in
bugs related to:
https://llvm.org/PR51575

https://alive2.llvm.org/ce/z/GpkFCt
This commit is contained in:
Sanjay Patel
2021-08-22 09:13:59 -04:00
parent d41e308f10
commit dcf659e821
2 changed files with 6 additions and 4 deletions
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4
llvm/lib/Analysis/InstructionSimplify.cpp
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@@ -5860,6 +5860,10 @@ static Value *simplifyIntrinsic(CallBase *Call, const SimplifyQuery &Q) {
if (match(Op0, m_Zero()) && match(Op1, m_Zero()))
return ConstantInt::getNullValue(F->getReturnType());
// Rotating -1 by anything is -1.
if (match(Op0, m_AllOnes()) && match(Op1, m_AllOnes()))
return ConstantInt::getAllOnesValue(F->getReturnType());
return nullptr;
}
case Intrinsic::experimental_constrained_fma: {

6
llvm/test/Transforms/InstSimplify/call.ll
View File

@@ -976,8 +976,7 @@ define <2 x i8> @fshr_zero_vec(<2 x i8> %shamt) {
define <2 x i7> @fshl_ones_vec(<2 x i7> %shamt) {
; CHECK-LABEL: @fshl_ones_vec(
; CHECK-NEXT: [[R:%.*]] = call <2 x i7> @llvm.fshl.v2i7(<2 x i7> <i7 undef, i7 -1>, <2 x i7> <i7 -1, i7 undef>, <2 x i7> [[SHAMT:%.*]])
; CHECK-NEXT: ret <2 x i7> [[R]]
; CHECK-NEXT: ret <2 x i7> <i7 -1, i7 -1>
;
%r = call <2 x i7> @llvm.fshl.v2i7(<2 x i7> <i7 undef, i7 -1>, <2 x i7> <i7 -1, i7 undef>, <2 x i7> %shamt)
ret <2 x i7> %r
@@ -985,8 +984,7 @@ define <2 x i7> @fshl_ones_vec(<2 x i7> %shamt) {
define i9 @fshr_ones(i9 %shamt) {
; CHECK-LABEL: @fshr_ones(
; CHECK-NEXT: [[R:%.*]] = call i9 @llvm.fshr.i9(i9 -1, i9 -1, i9 [[SHAMT:%.*]])
; CHECK-NEXT: ret i9 [[R]]
; CHECK-NEXT: ret i9 -1
;
%r = call i9 @llvm.fshr.i9(i9 -1, i9 -1, i9 %shamt)
ret i9 %r