[llvm] r260193 - [GMR/OperandBundles] Teach getModRefBehavior about operand bundles

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Mon Feb  8 20:31:47 2016
New Revision: 260193

URL: http://llvm.org/viewvc/llvm-project?rev=260193&view=rev
Log:
[GMR/OperandBundles] Teach getModRefBehavior about operand bundles

In general, memory restrictions on a called function (e.g. readnone)
cannot be transferred to a CallSite that has operand bundles.  It is
possible to make this inference smarter, but lets fix the behavior to be
correct first.

Added:
    llvm/trunk/test/Feature/OperandBundles/pr26510.ll
Modified:
    llvm/trunk/lib/Analysis/GlobalsModRef.cpp

Modified: llvm/trunk/lib/Analysis/GlobalsModRef.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/GlobalsModRef.cpp?rev=260193&r1=260192&r2=260193&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/GlobalsModRef.cpp (original)
+++ llvm/trunk/lib/Analysis/GlobalsModRef.cpp Mon Feb  8 20:31:47 2016
@@ -243,13 +243,14 @@ FunctionModRefBehavior
 GlobalsAAResult::getModRefBehavior(ImmutableCallSite CS) {
   FunctionModRefBehavior Min = FMRB_UnknownModRefBehavior;
 
-  if (const Function *F = CS.getCalledFunction())
-    if (FunctionInfo *FI = getFunctionInfo(F)) {
-      if (FI->getModRefInfo() == MRI_NoModRef)
-        Min = FMRB_DoesNotAccessMemory;
-      else if ((FI->getModRefInfo() & MRI_Mod) == 0)
-        Min = FMRB_OnlyReadsMemory;
-    }
+  if (!CS.hasOperandBundles())
+    if (const Function *F = CS.getCalledFunction())
+      if (FunctionInfo *FI = getFunctionInfo(F)) {
+        if (FI->getModRefInfo() == MRI_NoModRef)
+          Min = FMRB_DoesNotAccessMemory;
+        else if ((FI->getModRefInfo() & MRI_Mod) == 0)
+          Min = FMRB_OnlyReadsMemory;
+      }
 
   return FunctionModRefBehavior(AAResultBase::getModRefBehavior(CS) & Min);
 }

Added: llvm/trunk/test/Feature/OperandBundles/pr26510.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Feature/OperandBundles/pr26510.ll?rev=260193&view=auto
==============================================================================
--- llvm/trunk/test/Feature/OperandBundles/pr26510.ll (added)
+++ llvm/trunk/test/Feature/OperandBundles/pr26510.ll Mon Feb  8 20:31:47 2016
@@ -0,0 +1,27 @@
+; RUN: opt -S -globals-aa -functionattrs < %s | FileCheck %s
+; RUN: opt -S -O3 < %s | FileCheck %s
+
+; Apart from checking for the direct cause of the bug, we also check
+; if any problematic aliasing rules have accidentally snuck into -O3.
+;
+; Since the "abc" operand bundle is not a special operand bundle that
+; LLVM knows about, all of the stores and loads in @test below have to
+; stay.
+
+declare void @foo() readnone
+
+; CHECK-LABEL: define i8* @test(i8* %p) {
+; CHECK:   %a = alloca i8*, align 8
+; CHECK:   store i8* %p, i8** %a, align 8
+; CHECK:   call void @foo() [ "abc"(i8** %a) ]
+; CHECK:   %reload = load i8*, i8** %a, align 8
+; CHECK:   ret i8* %reload
+; CHECK: }
+
+define i8* @test(i8* %p) {
+  %a = alloca i8*, align 8
+  store i8* %p, i8** %a, align 8
+  call void @foo() ["abc" (i8** %a)]
+  %reload = load i8*, i8** %a, align 8
+  ret i8* %reload
+}