From: Igor Laevsky <igmyrj@gmail.com>
Date: Wed, 28 Oct 2015 17:54:48 +0000 (+0000)
Subject: [AliasAnalysis] Take into account readnone attribute for the function arguments
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=5b6459c883acde4b6eb4c2bbabf37905948c6ca5

[AliasAnalysis] Take into account readnone attribute for the function arguments

Differential Revision: http://reviews.llvm.org/D13992



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251535 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index 26578b83c8b..1f7e82d3158 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -619,6 +619,9 @@ ModRefInfo BasicAAResult::getArgModRefInfo(ImmutableCallSite CS,
   if (CS.paramHasAttr(ArgIdx + 1, Attribute::ReadOnly))
     return MRI_Ref;
 
+  if (CS.paramHasAttr(ArgIdx + 1, Attribute::ReadNone))
+    return MRI_NoModRef;
+
   return AAResultBase::getArgModRefInfo(CS, ArgIdx);
 }
 
diff --git a/test/Analysis/BasicAA/modref.ll b/test/Analysis/BasicAA/modref.ll
index 342d3fc23cd..e42793936c3 100644
--- a/test/Analysis/BasicAA/modref.ll
+++ b/test/Analysis/BasicAA/modref.ll
@@ -216,6 +216,17 @@ define i32 @test12(i32* %P, i32* %P2, i32* %P3) {
   ; CHECK: ret i32 %Diff
 }
 
+; CHECK-LABEL: @test13(
+define i32 @test13(i32* %P, i32* %P2) {
+  %V1 = load i32, i32* %P
+  call i32 @func_argmemonly(i32* readnone %P2)
+  %V2 = load i32, i32* %P
+  %Diff = sub i32 %V1, %V2
+  ret i32 %Diff
+  ; CHECK-NOT: load
+  ; CHECK: ret i32 0
+}
+
 declare void @llvm.memset.p0i8.i32(i8* nocapture, i8, i32, i32, i1) nounwind
 declare void @llvm.memset.p0i8.i8(i8* nocapture, i8, i8, i32, i1) nounwind
 declare void @llvm.memcpy.p0i8.p0i8.i8(i8* nocapture, i8* nocapture, i8, i32, i1) nounwind