[llvm-commits] [llvm] r120370 - in /llvm/trunk: lib/Analysis/BasicAliasAnalysis.cpp test/Transforms/DeadStoreElimination/simple.ll

[Chris Lattner]

Author: lattner
Date: Mon Nov 29 18:43:16 2010
New Revision: 120370

URL: http://llvm.org/viewvc/llvm-project?rev=120370&view=rev
Log:
enhance basicaa to return "Mod" for a memcpy call when the
queried location doesn't overlap the source, and add a testcase.

Modified:
    llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
    llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll

Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=120370&r1=120369&r2=120370&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Mon Nov 29 18:43:16 2010
@@ -687,10 +687,15 @@
         Len = LenCI->getZExtValue();
       Value *Dest = II->getArgOperand(0);
       Value *Src = II->getArgOperand(1);
+      // If it can't overlap the source dest, then it doesn't modref the loc.
       if (isNoAlias(Location(Dest, Len), Loc)) {
         if (isNoAlias(Location(Src, Len), Loc))
           return NoModRef;
+        // If it can't overlap the dest, then worst case it reads the loc.
         Min = Ref;
+      } else if (isNoAlias(Location(Src, Len), Loc)) {
+        // If it can't overlap the source, then worst case it mutates the loc.
+        Min = Mod;
       }
       break;
     }

Modified: llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll?rev=120370&r1=120369&r2=120370&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll (original)
+++ llvm/trunk/test/Transforms/DeadStoreElimination/simple.ll Mon Nov 29 18:43:16 2010
@@ -55,16 +55,27 @@
 ; CHECK-NEXT: ret void
 }
 
-declare void @llvm.memset.i32(i8*, i8, i32, i32)
+declare void @llvm.memset.i64(i8*, i8, i64, i32)
+declare void @llvm.memcpy.i64(i8*, i8*, i64, i32)
 
 ; Should delete store of 10 even though memset is a may-store to P (P and Q may
 ; alias).
 define void @test6(i32 *%p, i8 *%q) {
   store i32 10, i32* %p, align 4       ;; dead.
-  call void @llvm.memset.i32(i8* %q, i8 42, i32 900, i32 1)
+  call void @llvm.memset.i64(i8* %q, i8 42, i64 900, i32 1)
   store i32 30, i32* %p, align 4
   ret void
 ; CHECK: @test6
 ; CHECK-NEXT: call void @llvm.memset
 }
 
+; Should delete store of 10 even though memcpy is a may-store to P (P and Q may
+; alias).
+define void @test7(i32 *%p, i8 *%q, i8* noalias %r) {
+  store i32 10, i32* %p, align 4       ;; dead.
+  call void @llvm.memcpy.i64(i8* %q, i8* %r, i64 900, i32 1)
+  store i32 30, i32* %p, align 4
+  ret void
+; CHECK: @test7
+; CHECK-NEXT: call void @llvm.memcpy
+}