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[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.

llvm-svn: 260193
This commit is contained in:
Sanjoy Das 2016-02-09 02:31:47 +00:00
parent 4a33ab7b2c
commit ca2edc7ad5
2 changed files with 35 additions and 7 deletions
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15
llvm/lib/Analysis/GlobalsModRef.cpp
View File

@ -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);
}

27
llvm/test/Feature/OperandBundles/pr26510.ll Normal file
View File

@ -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
}