RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2024-12-02 08:46:23 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

At Chris' suggestion, move the liveness and worklist datastructures into

Browse Source 
instance variables so they can be allocated just once, and reuse the worklist
as the dead list as well.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52618 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2008-06-23 06:13:12 +00:00
parent cbfe5bbe88
commit ae18bd4246
1 changed files with 11 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
lib/Transforms/Scalar/ADCE.cpp
View File

@ -22,6 +22,7 @@
#include "llvm/Support/InstIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
using namespace llvm;
@ -32,6 +33,9 @@ namespace {
static char ID; // Pass identification, replacement for typeid
ADCE() : FunctionPass((intptr_t)&ID) {}
SmallPtrSet<Instruction*, 1024> alive;
SmallVector<Instruction*, 1024> worklist;
virtual bool runOnFunction(Function& F);
virtual void getAnalysisUsage(AnalysisUsage& AU) const {
@ -45,8 +49,8 @@ char ADCE::ID = 0;
static RegisterPass<ADCE> X("adce", "Aggressive Dead Code Elimination");
bool ADCE::runOnFunction(Function& F) {
SmallPtrSet<Instruction*, 32> alive;
std::vector<Instruction*> worklist;
alive.clear();
worklist.clear();
// Collect the set of "root" instructions that are known live.
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
@ -71,20 +75,20 @@ bool ADCE::runOnFunction(Function& F) {
// The inverse of the live set is the dead set. These are those instructions
// which have no side effects and do not influence the control flow or return
// value of the function, and may therefore be deleted safely.
SmallPtrSet<Instruction*, 32> dead;
// NOTE: We reuse the worklist vector here for memory efficiency.
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
if (!alive.count(I.getInstructionIterator())) {
dead.insert(I.getInstructionIterator());
worklist.push_back(I.getInstructionIterator());
I->dropAllReferences();
}
for (SmallPtrSet<Instruction*, 32>::iterator I = dead.begin(),
E = dead.end(); I != E; ++I) {
for (SmallVector<Instruction*, 1024>::iterator I = worklist.begin(),
E = worklist.end(); I != E; ++I) {
NumRemoved++;
(*I)->eraseFromParent();
}
return !dead.empty();
return !worklist.empty();
}
FunctionPass *llvm::createAggressiveDCEPass() {