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| author | Dale Johannesen <dalej@apple.com> | 2007-06-08 00:34:27 +0000 |
|---|---|---|
| committer | Dale Johannesen <dalej@apple.com> | 2007-06-08 00:34:27 +0000 |
| commit | 53af4c01a87b8a60bce2cc19e5249aaed52d6523 (patch) | |
| tree | 2ed9c42e3341087a348b15e5146c8835870779b6 /lib/CodeGen/BranchFolding.cpp | |
| parent | 0ab301c5fa5656b812db8cc944ab41259c8990dc (diff) | |
| download | llvm-53af4c01a87b8a60bce2cc19e5249aaed52d6523.tar.gz llvm-53af4c01a87b8a60bce2cc19e5249aaed52d6523.tar.bz2 llvm-53af4c01a87b8a60bce2cc19e5249aaed52d6523.tar.xz | |
Throttle tail merging; handling blocks with large numbers of predecessors
is too slow.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37509 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/BranchFolding.cpp')
| -rw-r--r-- | lib/CodeGen/BranchFolding.cpp | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp index ffde173e69..1125511a84 100644 --- a/lib/CodeGen/BranchFolding.cpp +++ b/lib/CodeGen/BranchFolding.cpp @@ -564,6 +564,9 @@ 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; @@ -577,7 +580,8 @@ 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. - MadeChange |= TryMergeBlocks(NULL, NULL); + if (MergePotentials.size() < THRESHOLD) + MadeChange |= TryMergeBlocks(NULL, NULL); // Look at blocks (IBB) with multiple predecessors (PBB). // We change each predecessor to a canonical form, by @@ -599,7 +603,7 @@ 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) { + if (!I->succ_empty() && I->pred_size() >= 2 && I->pred_size() < THRESHOLD) { MachineBasicBlock *IBB = I; MachineBasicBlock *PredBB = prior(I); MergePotentials.clear(); |