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InstCombine: Turn mul.with.overflow(X, 2) into the cheaper add.with.overflow(X, X)

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llvm-svn: 131789
This commit is contained in:
Benjamin Kramer 2011-05-21 09:22:06 +00:00
parent 28ea8de263
commit 51d1eac4bc
2 changed files with 35 additions and 0 deletions
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14
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -535,6 +535,20 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
}
// [su]mul.with.overflow(X, 2) -> [su]add.with.overflow(X, X)
if (RHSI->equalsInt(2)) {
Intrinsic::ID Add =
II->getIntrinsicID() == Intrinsic::smul_with_overflow ?
Intrinsic::sadd_with_overflow : Intrinsic::uadd_with_overflow;
Module *M = II->getParent()->getParent()->getParent();
const Type *Ty = RHSI->getType();
Function *F = Intrinsic::getDeclaration(M, Add, &Ty, 1);
Value *Ops[] = { II->getArgOperand(0), II->getArgOperand(0) };
return CallInst::Create(F, Ops, Ops+2);
}
}
break;
case Intrinsic::ppc_altivec_lvx:

21
test/Transforms/InstCombine/intrinsics.ll
View File

@ -114,6 +114,7 @@ define i8 @umultest2(i8 %A, i1* %overflowPtr) {
%ov.result.32 = type { i32, i1 }
declare %ov.result.32 @llvm.umul.with.overflow.i32(i32, i32) nounwind readnone
declare %ov.result.32 @llvm.smul.with.overflow.i32(i32, i32) nounwind readnone
define i32 @umultest3(i32 %n) nounwind {
%shr = lshr i32 %n, 2
@ -139,6 +140,26 @@ define i32 @umultest4(i32 %n) nounwind {
; CHECK: umul.with.overflow
}
define i32 @umultest5(i32 %n) nounwind {
%mul = call %ov.result.32 @llvm.umul.with.overflow.i32(i32 %n, i32 2)
%ov = extractvalue %ov.result.32 %mul, 1
%res = extractvalue %ov.result.32 %mul, 0
%ret = select i1 %ov, i32 -1, i32 %res
ret i32 %ret
; CHECK: @umultest5
; CHECK: llvm.uadd.with.overflow.i32(i32 %n, i32 %n)
}
define i32 @smultest1(i32 %n) nounwind {
%mul = call %ov.result.32 @llvm.smul.with.overflow.i32(i32 %n, i32 2)
%ov = extractvalue %ov.result.32 %mul, 1
%res = extractvalue %ov.result.32 %mul, 0
%ret = select i1 %ov, i32 -1, i32 %res
ret i32 %ret
; CHECK: @smultest1
; CHECK: llvm.sadd.with.overflow.i32(i32 %n, i32 %n)
}
define void @powi(double %V, double *%P) {
entry:
%A = tail call double @llvm.powi.f64(double %V, i32 -1) nounwind