[llvm-commits] [llvm] r115296 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineCalls.cpp test/Transforms/InstCombine/memcpy.ll

[Chris Lattner]

Author: lattner
Date: Fri Oct  1 00:51:02 2010
New Revision: 115296

URL: http://llvm.org/viewvc/llvm-project?rev=115296&view=rev
Log:
fix PR8267 - Instcombine shouldn't optimizer away volatile memcpy's.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/memcpy.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=115296&r1=115295&r2=115296&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Fri Oct  1 00:51:02 2010
@@ -280,7 +280,8 @@
 
     // memmove/cpy/set of zero bytes is a noop.
     if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
-      if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
+      if (NumBytes->isNullValue())
+        return EraseInstFromFunction(CI);
 
       if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
         if (CI->getZExtValue() == 1) {
@@ -289,6 +290,10 @@
           // alignment is sufficient.
         }
     }
+    
+    // No other transformations apply to volatile transfers.
+    if (MI->isVolatile())
+      return 0;
 
     // If we have a memmove and the source operation is a constant global,
     // then the source and dest pointers can't alias, so we can change this

Modified: llvm/trunk/test/Transforms/InstCombine/memcpy.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/memcpy.ll?rev=115296&r1=115295&r2=115296&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/memcpy.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/memcpy.ll Fri Oct  1 00:51:02 2010
@@ -2,9 +2,18 @@
 
 declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
 
-define void @test4(i8* %a) {
+define void @test1(i8* %a) {
         tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 false)
         ret void
-}
-; CHECK: define void @test4
+; CHECK: define void @test1
 ; CHECK-NEXT: ret void
+}
+
+
+; PR8267
+define void @test2(i8* %a) {
+        tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 true)
+        ret void
+; CHECK: define void @test2
+; CHECK-NEXT: call void @llvm.memcpy
+}