6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-20 14:29:27 +00:00
Code Issues Projects Releases Wiki Activity

When checking if an Argument escapes, check if

Browse Source 
the argument is marked nocapture - no need to
analyze the argument if the answer is already
known!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61753 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2009-01-05 21:19:53 +00:00
parent 7e66c0d43a
commit 91c9c31033
1 changed files with 13 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -35,10 +35,11 @@ using namespace llvm;
// Useful predicates // Useful predicates
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
// Determine if an AllocationInst instruction escapes from the function it is // Determine if a value escapes from the function it is contained in (being
// contained in. If it does not escape, there is no way for another function to // returned by the function does not count as escaping here). If a value local
// mod/ref it. We do this by looking at its uses and determining if the uses // to the function does not escape, there is no way another function can mod/ref
// can escape (recursively). // it. We do this by looking at its uses and determining if they can escape
// (recursively).
static bool AddressMightEscape(const Value *V) { static bool AddressMightEscape(const Value *V) {
for (Value::use_const_iterator UI = V->use_begin(), E = V->use_end(); for (Value::use_const_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) { UI != E; ++UI) {
@ -163,10 +164,15 @@ static bool isNonEscapingLocalObject(const Value *V) {
return !AddressMightEscape(V); return !AddressMightEscape(V);
// If this is an argument that corresponds to a byval or noalias argument, // If this is an argument that corresponds to a byval or noalias argument,
// it can't escape either. // then it has not escaped before entering the function. Check if it escapes
// inside the function.
if (const Argument *A = dyn_cast<Argument>(V)) if (const Argument *A = dyn_cast<Argument>(V))
if (A->hasByValAttr() || A->hasNoAliasAttr()) if (A->hasByValAttr() || A->hasNoAliasAttr()) {
// Don't bother analyzing arguments already known not to escape.
if (A->hasNoCaptureAttr())
return true;
return !AddressMightEscape(V); return !AddressMightEscape(V);
}
return false; return false;
} }