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Make UnreachableMachineBlockElim preserve MachineDominatorTree and

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MachineLoopInfo.

llc now runs MachineLoopInfo and MachineDominatorTree only twice, instead
of three times.

llvm-svn: 77759
This commit is contained in:
Dan Gohman 2009-08-01 00:34:30 +00:00
parent e05a157134
commit c1dc8ac240
1 changed files with 15 additions and 0 deletions
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15
lib/CodeGen/UnreachableBlockElim.cpp
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@ -26,8 +26,10 @@
#include "llvm/Function.h"
#include "llvm/Pass.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
@ -88,6 +90,7 @@ namespace {
class VISIBILITY_HIDDEN UnreachableMachineBlockElim :
public MachineFunctionPass {
virtual bool runOnMachineFunction(MachineFunction &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
MachineModuleInfo *MMI;
public:
static char ID; // Pass identification, replacement for typeid
@ -102,10 +105,18 @@ Y("unreachable-mbb-elimination",
const PassInfo *const llvm::UnreachableMachineBlockElimID = &Y;
void UnreachableMachineBlockElim::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<MachineLoopInfo>();
AU.addPreserved<MachineDominatorTree>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
SmallPtrSet<MachineBasicBlock*, 8> Reachable;
MMI = getAnalysisIfAvailable<MachineModuleInfo>();
MachineDominatorTree *MDT = getAnalysisIfAvailable<MachineDominatorTree>();
MachineLoopInfo *MLI = getAnalysisIfAvailable<MachineLoopInfo>();
// Mark all reachable blocks.
for (df_ext_iterator<MachineFunction*, SmallPtrSet<MachineBasicBlock*, 8> >
@ -123,6 +134,10 @@ bool UnreachableMachineBlockElim::runOnMachineFunction(MachineFunction &F) {
if (!Reachable.count(BB)) {
DeadBlocks.push_back(BB);
// Update dominator and loop info.
if (MLI) MLI->removeBlock(BB);
if (MDT && MDT->getNode(BB)) MDT->eraseNode(BB);
while (BB->succ_begin() != BB->succ_end()) {
MachineBasicBlock* succ = *BB->succ_begin();