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Pointer-comparison folding should look through returned-argument functions

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For functions which are known to return a specific argument, pointer-comparison
folding can look through the function calls as part of its analysis.

Differential Revision: http://reviews.llvm.org/D9387

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275039 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2016-07-11 03:37:59 +00:00
parent 0017f3683d
commit b0d67723f0
2 changed files with 35 additions and 0 deletions
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5
lib/Analysis/InstructionSimplify.cpp
View File

@ -621,6 +621,11 @@ static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
break; break;
V = GA->getAliasee(); V = GA->getAliasee();
} else { } else {
if (auto CS = CallSite(V))
if (Value *RV = CS.getReturnedArgOperand()) {
V = RV;
continue;
}
break; break;
} }
assert(V->getType()->getScalarType()->isPointerTy() && assert(V->getType()->getScalarType()->isPointerTy() &&

30
test/Transforms/InstSimplify/returned.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt -instsimplify -S < %s | FileCheck %s
define i1 @bitcast() {
; CHECK-LABEL: @bitcast(
%a = alloca i32
%b = alloca i64
%x = bitcast i32* %a to i8*
%z = bitcast i64* %b to i8*
%y = call i8* @func1(i8* %z)
%cmp = icmp eq i8* %x, %y
ret i1 %cmp
; CHECK-NEXT: ret i1 false
}
%gept = type { i32, i32 }
define i1 @gep3() {
; CHECK-LABEL: @gep3(
%x = alloca %gept, align 8
%a = getelementptr %gept, %gept* %x, i64 0, i32 0
%y = call %gept* @func2(%gept* %x)
%b = getelementptr %gept, %gept* %y, i64 0, i32 1
%equal = icmp eq i32* %a, %b
ret i1 %equal
; CHECK-NEXT: ret i1 false
}
declare i8* @func1(i8* returned) nounwind readnone
declare %gept* @func2(%gept* returned) nounwind readnone