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Integrate the readonly/readnone logic more deeply

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into alias analysis.  This meant updating the API
which now has versions of the getModRefBehavior,
doesNotAccessMemory and onlyReadsMemory methods
which take a callsite parameter.  These should be
used unless the callsite is not known, since in
general they can do a better job than the versions
that take a function.  Also, users should no longer
call the version of getModRefBehavior that takes
both a function and a callsite.  To reduce the
chance of misuse it is now protected.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44487 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands
2007-12-01 07:51:45 +00:00
parent e3110d0825
commit dff6710717
12 changed files with 122 additions and 90 deletions
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39
lib/Analysis/AliasAnalysis.cpp
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@@ -27,6 +27,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
#include "llvm/BasicBlock.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Target/TargetData.h"
@@ -112,16 +113,40 @@ AliasAnalysis::getModRefInfo(StoreInst *S, Value *P, unsigned Size) {
return pointsToConstantMemory(P) ? NoModRef : Mod;
}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(CallSite CS,
std::vector<PointerAccessInfo> *Info) {
if (CS.paramHasAttr(0, ParamAttr::ReadNone))
// Can't do better than this.
return DoesNotAccessMemory;
ModRefBehavior MRB = UnknownModRefBehavior;
if (Function *F = CS.getCalledFunction())
MRB = getModRefBehavior(F, CS, Info);
if (MRB != DoesNotAccessMemory && CS.paramHasAttr(0, ParamAttr::ReadOnly))
return OnlyReadsMemory;
return MRB;
}
AliasAnalysis::ModRefBehavior
AliasAnalysis::getModRefBehavior(Function *F,
std::vector<PointerAccessInfo> *Info) {
if (F->paramHasAttr(0, ParamAttr::ReadNone))
// Can't do better than this.
return DoesNotAccessMemory;
ModRefBehavior MRB = getModRefBehavior(F, CallSite(), Info);
if (MRB != DoesNotAccessMemory && F->paramHasAttr(0, ParamAttr::ReadOnly))
return OnlyReadsMemory;
return MRB;
}
AliasAnalysis::ModRefResult
AliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
ModRefResult Mask = ModRef;
if (Function *F = CS.getCalledFunction()) {
ModRefBehavior MRB = getModRefBehavior(F, CallSite());
if (MRB == OnlyReadsMemory)
Mask = Ref;
else if (MRB == DoesNotAccessMemory)
return NoModRef;
}
ModRefBehavior MRB = getModRefBehavior(CS);
if (MRB == OnlyReadsMemory)
Mask = Ref;
else if (MRB == DoesNotAccessMemory)
return NoModRef;
if (!AA) return Mask;