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Make FunctionAttrs use AliasAnalysis::getModRefBehavior, now that it

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knows about intrinsic functions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118410 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-11-08 16:10:15 +00:00
parent 431c794ade
commit 3c97f7af9e
2 changed files with 34 additions and 19 deletions
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51
lib/Transforms/IPO/FunctionAttrs.cpp
View File

@ -40,7 +40,7 @@ STATISTIC(NumNoAlias, "Number of function returns marked noalias");
namespace {
struct FunctionAttrs : public CallGraphSCCPass {
static char ID; // Pass identification, replacement for typeid
FunctionAttrs() : CallGraphSCCPass(ID) {
FunctionAttrs() : CallGraphSCCPass(ID), AA(0) {
initializeFunctionAttrsPass(*PassRegistry::getPassRegistry());
}
@ -62,10 +62,14 @@ namespace {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<AliasAnalysis>();
CallGraphSCCPass::getAnalysisUsage(AU);
}
bool PointsToLocalOrConstantMemory(Value *V);
private:
AliasAnalysis *AA;
};
}
@ -167,26 +171,35 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
// Some instructions can be ignored even if they read or write memory.
// Detect these now, skipping to the next instruction if one is found.
CallSite CS(cast<Value>(I));
if (CS && CS.getCalledFunction()) {
if (CS) {
// Ignore calls to functions in the same SCC.
if (SCCNodes.count(CS.getCalledFunction()))
if (CS.getCalledFunction() && SCCNodes.count(CS.getCalledFunction()))
continue;
// Ignore intrinsics that only access local memory.
if (unsigned id = CS.getCalledFunction()->getIntrinsicID())
if (AliasAnalysis::getIntrinsicModRefBehavior(id) ==
AliasAnalysis::AccessesArguments) {
// Check that all pointer arguments point to local memory.
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI) {
Value *Arg = *CI;
if (Arg->getType()->isPointerTy() &&
!PointsToLocalOrConstantMemory(Arg))
// Writes memory. Just give up.
return false;
}
// Only reads and writes local memory.
continue;
switch (AA->getModRefBehavior(CS)) {
case AliasAnalysis::DoesNotAccessMemory:
// Ignore calls that don't access memory.
continue;
case AliasAnalysis::OnlyReadsMemory:
// Handle calls that only read from memory.
ReadsMemory = true;
continue;
case AliasAnalysis::AccessesArguments:
// Check whether all pointer arguments point to local memory, and
// ignore calls that only access local memory.
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI) {
Value *Arg = *CI;
if (Arg->getType()->isPointerTy() &&
!PointsToLocalOrConstantMemory(Arg))
// Writes memory. Just give up.
return false;
}
// Only reads and writes local memory.
continue;
default:
// Otherwise, be conservative.
break;
}
} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
// Ignore non-volatile loads from local memory.
if (!LI->isVolatile() &&
@ -387,6 +400,8 @@ bool FunctionAttrs::AddNoAliasAttrs(const CallGraphSCC &SCC) {
}
bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
AA = &getAnalysis<AliasAnalysis>();
bool Changed = AddReadAttrs(SCC);
Changed |= AddNoCaptureAttrs(SCC);
Changed |= AddNoAliasAttrs(SCC);

2
test/Transforms/FunctionAttrs/2008-10-04-LocalMemory.ll
View File

@ -1,4 +1,4 @@
; RUN: opt < %s -functionattrs -S | FileCheck %s
; RUN: opt < %s -basicaa -functionattrs -S | FileCheck %s
%struct.X = type { i32*, i32* }