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Teach BasicAA a little something about the atomic intrinsics: they can only 

modify through the pointer they're given.

llvm-svn: 83959
This commit is contained in:
Nick Lewycky 2009-10-13 07:48:38 +00:00
parent 3eb172a02b
commit e2782c7614
2 changed files with 37 additions and 0 deletions
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21
llvm/lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -284,6 +284,27 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
if (!passedAsArg)
return NoModRef;
}
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) {
switch (II->getIntrinsicID()) {
default: break;
case Intrinsic::atomic_cmp_swap:
case Intrinsic::atomic_swap:
case Intrinsic::atomic_load_add:
case Intrinsic::atomic_load_sub:
case Intrinsic::atomic_load_and:
case Intrinsic::atomic_load_nand:
case Intrinsic::atomic_load_or:
case Intrinsic::atomic_load_xor:
case Intrinsic::atomic_load_max:
case Intrinsic::atomic_load_min:
case Intrinsic::atomic_load_umax:
case Intrinsic::atomic_load_umin:
if (alias(II->getOperand(1), Size, P, Size) == NoAlias)
return NoModRef;
break;
}
}
}
// The AliasAnalysis base class has some smarts, lets use them.

16
llvm/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll Normal file
View File

@ -0,0 +1,16 @@
; RUN: opt -gvn -S < %s | FileCheck %s
declare i8 @llvm.atomic.load.add.i8.p0i8(i8*, i8)
define void @foo(i8* %ptr) {
%P = getelementptr i8* %ptr, i32 0
%Q = getelementptr i8* %ptr, i32 1
; CHECK: getelementptr
%X = load i8* %P
; CHECK: = load
%Y = call i8 @llvm.atomic.load.add.i8.p0i8(i8* %Q, i8 1)
%Z = load i8* %P
; CHECK-NOT: = load
ret void
; CHECK: ret void
}