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Make throttle a hidden parameter, per review.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37511 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2007-06-08 01:08:52 +00:00
parent 397d405731
commit 1a90a5aebe
1 changed files with 11 additions and 6 deletions
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17
lib/CodeGen/BranchFolding.cpp
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@ -38,6 +38,12 @@ STATISTIC(NumTailMerge , "Number of block tails merged");
static cl::opt<cl::boolOrDefault> FlagEnableTailMerge("enable-tail-merge",
cl::init(cl::BOU_UNSET), cl::Hidden);
namespace {
// Throttle for huge numbers of predecessors (compile speed problems)
cl::opt<unsigned>
TailMergeThreshold("tail-merge-threshold",
cl::desc("Max number of predecessors to consider tail merging"),
cl::init(100), cl::Hidden);
struct BranchFolder : public MachineFunctionPass {
static char ID;
BranchFolder(bool defaultEnableTailMerge) :
@ -564,9 +570,6 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
return MadeChange;
}
// Throttle for huge numbers of predecessors (compile speed problems)
#define THRESHOLD 100
bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
if (!EnableTailMerge) return false;
@ -580,7 +583,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
MergePotentials.push_back(std::make_pair(HashEndOfMBB(I, 2U), I));
}
// See if we can do any tail merging on those.
if (MergePotentials.size() < THRESHOLD)
if (MergePotentials.size() < TailMergeThreshold)
MadeChange |= TryMergeBlocks(NULL, NULL);
// Look at blocks (IBB) with multiple predecessors (PBB).
@ -603,11 +606,13 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
// transformations.)
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
if (!I->succ_empty() && I->pred_size() >= 2 && I->pred_size() < THRESHOLD) {
if (!I->succ_empty() && I->pred_size() >= 2 &&
I->pred_size() < TailMergeThreshold) {
MachineBasicBlock *IBB = I;
MachineBasicBlock *PredBB = prior(I);
MergePotentials.clear();
for (MachineBasicBlock::pred_iterator P = I->pred_begin(), E2 = I->pred_end();
for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
E2 = I->pred_end();
P != E2; ++P) {
MachineBasicBlock* PBB = *P;
// Skip blocks that loop to themselves, can't tail merge these.