[llvm-commits] [llvm] r122785 - in /llvm/trunk: lib/Transforms/Scalar/EarlyCSE.cpp test/Transforms/EarlyCSE/basic.ll

[Chris Lattner]

Author: lattner
Date: Mon Jan  3 17:38:13 2011
New Revision: 122785

URL: http://llvm.org/viewvc/llvm-project?rev=122785&view=rev
Log:
Duncan deftly points out that readnone functions aren't
invalidated by stores, so they can be handled as 'simple'
operations.

Modified:
    llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp
    llvm/trunk/test/Transforms/EarlyCSE/basic.ll

Modified: llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp?rev=122785&r1=122784&r2=122785&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp Mon Jan  3 17:38:13 2011
@@ -56,6 +56,9 @@
     }
     
     static bool canHandle(Instruction *Inst) {
+      // This can only handle non-void readnone functions.
+      if (CallInst *CI = dyn_cast<CallInst>(Inst))
+        return CI->doesNotAccessMemory() && !CI->getType()->isVoidTy();
       return isa<CastInst>(Inst) || isa<BinaryOperator>(Inst) ||
              isa<GetElementPtrInst>(Inst) || isa<CmpInst>(Inst) ||
              isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
@@ -105,7 +108,8 @@
       Res ^= *I;
   } else {
     // nothing extra to hash in.
-    assert((isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
+    assert((isa<CallInst>(Inst) ||
+            isa<BinaryOperator>(Inst) || isa<GetElementPtrInst>(Inst) ||
             isa<SelectInst>(Inst) || isa<ExtractElementInst>(Inst) ||
             isa<InsertElementInst>(Inst) || isa<ShuffleVectorInst>(Inst)) &&
            "Invalid/unknown instruction");

Modified: llvm/trunk/test/Transforms/EarlyCSE/basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/EarlyCSE/basic.ll?rev=122785&r1=122784&r2=122785&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/EarlyCSE/basic.ll (original)
+++ llvm/trunk/test/Transforms/EarlyCSE/basic.ll Mon Jan  3 17:38:13 2011
@@ -106,3 +106,16 @@
   ; CHECK-NEXT: store i32 45
   ; CHECK-NEXT: ret void
 }
+
+;; Readnone functions aren't invalidated by stores.
+; CHECK: @test8
+define i32 @test8(i32 *%P) {
+  %V1 = call i32 @func(i32* %P) readnone
+  store i32 4, i32* %P
+  %V2 = call i32 @func(i32* %P) readnone
+  %Diff = sub i32 %V1, %V2
+  ret i32 %Diff
+  ; CHECK: ret i32 0
+}
+
+