Teach BasicAA a little something about the atomic intrinsics: they can only
modify through the pointer they're given.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83959 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 5fa87ff..2e3c75d 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -284,6 +284,27 @@
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.
diff --git a/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll b/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll
new file mode 100644
index 0000000..3ccbc2f
--- /dev/null
+++ b/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll
@@ -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
+}