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Simplify DCE code a lot

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llvm-svn: 1079
This commit is contained in:
Chris Lattner 2001-11-01 05:55:29 +00:00
parent 1942341fd4
commit 3b2c78da03
1 changed files with 5 additions and 26 deletions
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31
lib/Transforms/Scalar/DCE.cpp
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@ -34,33 +34,12 @@
#include "llvm/Assembly/Writer.h"
#include <algorithm>
struct ConstPoolDCE {
enum { EndOffs = 0 };
static bool isDCEable(const ConstPoolVal *CPV) {
// TODO: The bytecode writer requires that all used types are in the
// constant pool for the current method. This is messy and is really
// irritating. FIXME
return CPV->getType() != Type::TypeTy; // Don't DCE Type plane constants!
}
};
struct BasicBlockDCE {
enum { EndOffs = 1 };
static bool isDCEable(const Instruction *I) {
return !I->hasSideEffects();
}
};
template<class Container, class DCEController>
static bool RemoveUnusedDefs(Container &Vals, DCEController DCEControl) {
static bool RemoveUnusedDefs(BasicBlock::InstListType &Vals) {
bool Changed = false;
int Offset = DCEController::EndOffs;
for (typename Container::iterator DI = Vals.begin();
DI != Vals.end()-Offset; ) {
for (BasicBlock::InstListType::iterator DI = Vals.begin();
DI != Vals.end()-1; ) {
// Look for un"used" definitions...
if ((*DI)->use_empty() && DCEController::isDCEable(*DI)) {
if ((*DI)->use_empty() && !(*DI)->hasSideEffects()) {
// Bye bye
//cerr << "Removing: " << *DI;
delete Vals.remove(DI);
@ -272,7 +251,7 @@ static bool DoDCEPass(Method *M) {
// Loop through now and remove instructions that have no uses...
for (BBIt = M->begin(); BBIt != BBEnd; ++BBIt) {
Changed |= RemoveUnusedDefs((*BBIt)->getInstList(), BasicBlockDCE());
Changed |= RemoveUnusedDefs((*BBIt)->getInstList());
Changed |= RemoveSingularPHIs(*BBIt);
}