6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-04-13 15:37:24 +00:00
Code Issues Projects Releases Wiki Activity

Ignore instructions that are in trivially dead functions. This allows us

Browse Source 
to constify 14 globals instead of 4 in a trivial C++ testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15027 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-07-20 03:58:07 +00:00
parent d43b9fd1ae
commit 9ce300013d
1 changed files with 17 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
lib/Transforms/IPO/GlobalOpt.cpp
View File

@ -39,6 +39,16 @@ namespace {
Pass *llvm::createGlobalConstifierPass() { return new Constifier(); }
/// A lot of global constants are stored only in trivially dead setter
/// functions. Because we don't want to cycle between globaldce and this pass,
/// just do a simple check to catch the common case.
static bool ContainingFunctionIsTriviallyDead(Instruction *I) {
Function *F = I->getParent()->getParent();
if (!F->hasInternalLinkage()) return false;
F->removeDeadConstantUsers();
return F->use_empty();
}
/// isStoredThrough - Return false if the specified pointer is provably never
/// stored through. If we can't tell, we must conservatively assume it might.
///
@ -48,10 +58,13 @@ static bool isStoredThrough(Value *V) {
if (isStoredThrough(CE))
return true;
} else if (Instruction *I = dyn_cast<Instruction>(*UI)) {
if (I->getOpcode() == Instruction::GetElementPtr) {
if (isStoredThrough(I)) return true;
} else if (!isa<LoadInst>(*UI) && !isa<SetCondInst>(*UI))
return true; // Any other non-load instruction might store!
if (!ContainingFunctionIsTriviallyDead(I)) {
if (I->getOpcode() == Instruction::GetElementPtr) {
if (isStoredThrough(I)) return true;
} else if (!isa<LoadInst>(*UI) && !isa<SetCondInst>(*UI)) {
return true; // Any other non-load instruction might store!
}
}
} else {
// Otherwise must be a global or some other user.
return true;