Index: llvm/trunk/lib/Analysis/GlobalsModRef.cpp =================================================================== --- llvm/trunk/lib/Analysis/GlobalsModRef.cpp +++ llvm/trunk/lib/Analysis/GlobalsModRef.cpp @@ -498,7 +498,7 @@ // Can't do better than that! } else if (F->onlyReadsMemory()) { FI.addModRefInfo(MRI_Ref); - if (!F->isIntrinsic()) + if (!F->isIntrinsic() && !F->onlyAccessesArgMemory()) // This function might call back into the module and read a global - // consider every global as possibly being read by this function. FI.setMayReadAnyGlobal(); Index: llvm/trunk/test/Analysis/GlobalsModRef/func-memattributes.ll =================================================================== --- llvm/trunk/test/Analysis/GlobalsModRef/func-memattributes.ll +++ llvm/trunk/test/Analysis/GlobalsModRef/func-memattributes.ll @@ -0,0 +1,31 @@ +; RUN: opt < %s -disable-basicaa -globals-aa -dse -S | FileCheck %s + +@X = internal global i32 4 + +define void @test0() { +; CHECK-LABEL: @test0 +; CHECK: store i32 0, i32* @X +; CHECK-NEXT: call void @func_readonly() #0 +; CHECK-NEXT: store i32 1, i32* @X + store i32 0, i32* @X + call void @func_readonly() #0 + store i32 1, i32* @X + ret void +} + +define void @test1() { +; CHECK-LABEL: @test1 +; CHECK-NOT: store +; CHECK: call void @func_read_argmem_only() #1 +; CHECK-NEXT: store i32 3, i32* @X + store i32 2, i32* @X + call void @func_read_argmem_only() #1 + store i32 3, i32* @X + ret void +} + +declare void @func_readonly() #0 +declare void @func_read_argmem_only() #1 + +attributes #0 = { readonly } +attributes #1 = { readonly argmemonly }