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Change to depth-first traversal.

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llvm-svn: 37236
This commit is contained in:
Evan Cheng 2007-05-18 19:26:33 +00:00
parent 09b2912ab7
commit ad9ce3c5b2
1 changed files with 22 additions and 11 deletions
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33
lib/CodeGen/IfConversion.cpp
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@ -19,6 +19,7 @@
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
@ -237,8 +238,11 @@ void IfConverter::FeasibilityAnalysis(BBInfo &BBI) {
/// if-conversion candidates.
void IfConverter::InitialFunctionAnalysis(MachineFunction &MF,
std::vector<int> &Candidates) {
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *BB = I;
std::set<MachineBasicBlock*> Visited;
MachineBasicBlock *Entry = MF.begin();
for (df_ext_iterator<MachineBasicBlock*> DFI = df_ext_begin(Entry, Visited),
E = df_ext_end(Entry, Visited); DFI != E; ++DFI) {
MachineBasicBlock *BB = *DFI;
StructuralAnalysis(BB);
BBInfo &BBI = BBAnalysis[BB->getNumber()];
if (BBI.Kind == ICTriangleEntry || BBI.Kind == ICDiamondEntry)
@ -379,23 +383,30 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
TII->InsertBranch(*BBI.FalseBB, *BBI.FalseBB->succ_begin(), NULL,NewCond);
// Merge the 'true' and 'false' blocks by copying the instructions
// from the 'false' block to the 'true' block.
MergeBlocks(TrueBBI, FalseBBI);
// from the 'false' block to the 'true' block. That is, unless the true
// block would clobber the predicate, in that case, do the opposite.
BBInfo *CvtBBI;
if (!TrueBBI.ClobbersPred) {
MergeBlocks(TrueBBI, FalseBBI);
CvtBBI = &TrueBBI;
} else {
MergeBlocks(FalseBBI, TrueBBI);
CvtBBI = &FalseBBI;
}
// Remove the conditional branch from entry to the blocks.
BBI.Size -= TII->RemoveBranch(*BBI.BB);
// Merge the combined block into the entry of the diamond if the entry
// block is the only predecessor. Otherwise, insert an unconditional
// branch.
BBInfo *CvtBBI = &TrueBBI;
if (BBI.TrueBB->pred_size() == 1) {
BBI.BB->removeSuccessor(BBI.TrueBB);
MergeBlocks(BBI, TrueBBI);
// block is its only predecessor. Otherwise, insert an unconditional
// branch from entry to the if-converted block.
if (CvtBBI->BB->pred_size() == 1) {
BBI.BB->removeSuccessor(CvtBBI->BB);
MergeBlocks(BBI, *CvtBBI);
CvtBBI = &BBI;
} else {
std::vector<MachineOperand> NoCond;
TII->InsertBranch(*BBI.BB, BBI.TrueBB, NULL, NoCond);
TII->InsertBranch(*BBI.BB, CvtBBI->BB, NULL, NoCond);
}
// If the if-converted block fallthrough into the tail block, then