Author: clamb
Date: Wed Aug 1 20:18:14 2007
New Revision: 40711
URL: http://llvm.org/viewvc/llvm-project?rev=40711&view=rev
Log:
Teach BasicAA about noalias parameter attributes, but do it correctly this time.
Added:
llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndCalls.ll
llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndGEP.ll
Modified:
llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
Modified: llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp?rev=40711&r1=40710&r2=40711&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp (original)
+++ llvm/trunk/lib/Analysis/BasicAliasAnalysis.cpp Wed Aug 1 20:18:14 2007
@@ -18,6 +18,7 @@
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
+#include "llvm/ParameterAttributes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
@@ -260,6 +261,21 @@
return AliasAnalysis::getModRefInfo(CS, P, Size);
}
+static bool isNoAliasArgument(const Argument *Arg) {
+ const Function *Func = Arg->getParent();
+ const ParamAttrsList *Attr = Func->getFunctionType()->getParamAttrs();
+ if (Attr) {
+ unsigned Idx = 1;
+ for (Function::const_arg_iterator I = Func->arg_begin(),
+ E = Func->arg_end(); I != E; ++I, ++Idx) {
+ if (&(*I) == Arg &&
+ Attr->paramHasAttr(Idx, ParamAttr::NoAlias))
+ return true;
+ }
+ }
+ return false;
+}
+
// alias - Provide a bunch of ad-hoc rules to disambiguate in common cases,
such
// as array references. Note that this function is heavily tail recursive.
// Hopefully we have a smart C++ compiler. :)
@@ -298,10 +314,24 @@
if (isa<Argument>(O1)) {
// Incoming argument cannot alias locally allocated object!
if (isa<AllocationInst>(O2)) return NoAlias;
+
+ // If they are two different objects, and one is a noalias argument
+ // then they do not alias.
+ if (O1 != O2 && isNoAliasArgument(cast<Argument>(O1)))
+ return NoAlias;
+
// Otherwise, nothing is known...
- } else if (isa<Argument>(O2)) {
+ }
+
+ if (isa<Argument>(O2)) {
// Incoming argument cannot alias locally allocated object!
if (isa<AllocationInst>(O1)) return NoAlias;
+
+ // If they are two different objects, and one is a noalias argument
+ // then they do not alias.
+ if (O1 != O2 && isNoAliasArgument(cast<Argument>(O2)))
+ return NoAlias;
+
// Otherwise, nothing is known...
} else if (O1 != O2) {
// If they are two different objects, we know that we have no alias...
Added: llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndCalls.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndCalls.ll?rev=40711&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndCalls.ll (added)
+++ llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndCalls.ll Wed Aug 1
20:18:14 2007
@@ -0,0 +1,10 @@
+; RUN: llvm-as %s -o - | opt -basicaa -aa-eval -print-all-alias-modref-info
-disable-output &| grep 'MayAlias: i32* %y, i32* %x'
+
+declare i32* @unclear(i32* %a)
+
+define void @foo(i32* noalias %x) {
+ %y = call i32* @unclear(i32* %x)
+ store i32 0, i32* %x
+ store i32 0, i32* %y
+ ret void
+}
Added: llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndGEP.ll
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndGEP.ll?rev=40711&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndGEP.ll (added)
+++ llvm/trunk/test/Analysis/BasicAA/2007-08-01-NoAliasAndGEP.ll Wed Aug 1
20:18:14 2007
@@ -0,0 +1,17 @@
+; RUN: llvm-as %s -o - | opt -basicaa -aa-eval -print-all-alias-modref-info
-disable-output &| grep '9 no alias'
+; RUN: llvm-as %s -o - | opt -basicaa -aa-eval -print-all-alias-modref-info
-disable-output &| grep '6 may alias'
+; RUN: llvm-as %s -o - | opt -basicaa -aa-eval -print-all-alias-modref-info
-disable-output &| grep 'MayAlias: i32* %pj, i32* %pi'
+
+define void @foo(i32* noalias %p, i32* noalias %q, i32 %i, i32 %j) {
+ %pi = getelementptr i32* %p, i32 %i
+ %qi = getelementptr i32* %q, i32 %i
+ %pj = getelementptr i32* %p, i32 %j
+ %qj = getelementptr i32* %q, i32 %j
+ store i32 0, i32* %p
+ store i32 0, i32* %pi
+ store i32 0, i32* %pj
+ store i32 0, i32* %q
+ store i32 0, i32* %qi
+ store i32 0, i32* %qj
+ ret void
+}
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