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simplify some code by using a helper function. This really really

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wants a 'nocapture' predicate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52304 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-06-16 06:38:26 +00:00
parent defa1c8034
commit 25df20f169
1 changed files with 16 additions and 22 deletions
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38
lib/Analysis/BasicAliasAnalysis.cpp
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@ -65,7 +65,8 @@ static bool AddressMightEscape(const Value *V) {
break; // next use
case Instruction::Call:
// If the call is to a few known safe intrinsics, we know that it does
// not escape
// not escape.
// TODO: Eventually just check the 'nocapture' attribute.
if (!isa<MemIntrinsic>(I))
return true;
break; // next use
@ -339,27 +340,20 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
if (CI->isTailCall())
return NoModRef;
// Allocations and byval arguments are "new" objects.
if (isa<AllocationInst>(Object) || isa<Argument>(Object)) {
// Okay, the pointer is to a stack allocated (or effectively so, for
// for noalias parameters) object. If the address of this object doesn't
// escape from this function body to a callee, then we know that no
// callees can mod/ref it unless they are actually passed it.
if (isa<AllocationInst>(Object) ||
cast<Argument>(Object)->hasByValAttr() ||
cast<Argument>(Object)->hasNoAliasAttr())
if (!AddressMightEscape(Object)) {
bool passedAsArg = false;
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI)
if (isa<PointerType>((*CI)->getType()) &&
(getUnderlyingObject(*CI) == P ||
alias(cast<Value>(CI), ~0U, P, ~0U) != NoAlias))
passedAsArg = true;
if (!passedAsArg)
return NoModRef;
}
// If the pointer is to a locally allocated object that does not escape,
// then the call can not mod/ref the pointer unless the call takes the
// argument without capturing it.
if (isNonEscapingLocalObject(Object)) {
bool passedAsArg = false;
// TODO: Eventually only check 'nocapture' arguments.
for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
CI != CE; ++CI)
if (isa<PointerType>((*CI)->getType()) &&
alias(cast<Value>(CI), ~0U, P, ~0U) != NoAlias)
passedAsArg = true;
if (!passedAsArg)
return NoModRef;
}
}