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revert 132986 to see if the bots go green.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132988 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2011-06-14 12:48:26 +00:00
parent bfdbd00d9d
commit 7a07083c25
3 changed files with 5 additions and 64 deletions
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26
lib/CodeGen/BranchFolding.cpp
View File

@ -799,22 +799,14 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
// First find blocks with no successors.
MergePotentials.clear();
for (MachineFunction::iterator I = MF.begin(), E = MF.end();
I != E && MergePotentials.size() < TailMergeThreshold; ++I) {
if (TriedMerging.count(I))
continue;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
if (I->succ_empty())
MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(I), I));
}
// If this is a large problem, avoid visiting the same basic blocks
// multiple times.
if (MergePotentials.size() == TailMergeThreshold)
for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
TriedMerging.insert(MergePotentials[i].getBlock());
// See if we can do any tail merging on those.
if (MergePotentials.size() >= 2)
if (MergePotentials.size() < TailMergeThreshold &&
MergePotentials.size() >= 2)
MadeChange |= TryTailMergeBlocks(NULL, NULL);
// Look at blocks (IBB) with multiple predecessors (PBB).
@ -838,17 +830,15 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
I != E; ++I) {
if (I->pred_size() >= 2) {
if (I->pred_size() >= 2 && I->pred_size() < TailMergeThreshold) {
SmallPtrSet<MachineBasicBlock *, 8> UniquePreds;
MachineBasicBlock *IBB = I;
MachineBasicBlock *PredBB = prior(I);
MergePotentials.clear();
for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
E2 = I->pred_end();
P != E2 && MergePotentials.size() < TailMergeThreshold; ++P) {
P != E2; ++P) {
MachineBasicBlock *PBB = *P;
if (TriedMerging.count(PBB))
continue;
// Skip blocks that loop to themselves, can't tail merge these.
if (PBB == IBB)
continue;
@ -901,12 +891,6 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(PBB), *P));
}
}
// If this is a large problem, avoid visiting the same basic blocks
// multiple times.
if (MergePotentials.size() == TailMergeThreshold)
for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
TriedMerging.insert(MergePotentials[i].getBlock());
if (MergePotentials.size() >= 2)
MadeChange |= TryTailMergeBlocks(IBB, PredBB);
// Reinsert an unconditional branch if needed.

2
lib/CodeGen/BranchFolding.h
View File

@ -10,7 +10,6 @@
#ifndef LLVM_CODEGEN_BRANCHFOLDING_HPP
#define LLVM_CODEGEN_BRANCHFOLDING_HPP
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include <vector>
@ -48,7 +47,6 @@ namespace llvm {
};
typedef std::vector<MergePotentialsElt>::iterator MPIterator;
std::vector<MergePotentialsElt> MergePotentials;
SmallPtrSet<const MachineBasicBlock*, 2> TriedMerging;
class SameTailElt {
MPIterator MPIter;

41
test/CodeGen/X86/tail-threshold.ll
View File

@ -1,41 +0,0 @@
; RUN: llc %s -stats -tail-merge-threshold 2 -o /dev/null |& FileCheck %s
; Test that we still do some merging if a block has more than
; tail-merge-threshold predecessors.
; CHECK: 2 branchfolding - Number of block tails merged
declare void @bar()
define void @foo(i32 %xxx) {
entry:
switch i32 %xxx, label %bb4 [
i32 0, label %bb0
i32 1, label %bb1
i32 2, label %bb2
i32 3, label %bb3
]
bb0:
call void @bar()
br label %bb5
bb1:
call void @bar()
br label %bb5
bb2:
call void @bar()
br label %bb5
bb3:
call void @bar()
br label %bb5
bb4:
call void @bar()
br label %bb5
bb5:
ret void
}