[llvm-commits] [llvm] r83959 - in /llvm/trunk: lib/Analysis/BasicAliasAnalysis.cpp test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll

[Nick Lewycky]

Author: nicholas
Date: Tue Oct 13 02:48:38 2009
New Revision: 83959

URL: http://llvm.org/viewvc/llvm-project?rev=83959&view=rev
Log:
Teach BasicAA a little something about the atomic intrinsics: they can only
modify through the pointer they're given.

Added:
    llvm/trunk/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll
Modified:
    llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp

Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=83959&r1=83958&r2=83959&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Tue Oct 13 02:48:38 2009
@@ -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.

Added: llvm/trunk/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll?rev=83959&view=auto

==============================================================================
--- llvm/trunk/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll (added)
+++ llvm/trunk/test/Analysis/BasicAA/2009-10-13-AtomicModRef.ll Tue Oct 13 02:48:38 2009
@@ -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
+}