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Make stable_sort in tail merging actually be stable (it never was, but didn't

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matter until my last change).  Reenable tail merging by default.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37354 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2007-05-29 23:47:50 +00:00
parent 58fbb9f5ba
commit 95ef406e0f
2 changed files with 18 additions and 3 deletions
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4
include/llvm/Target/TargetMachine.h
View File

@ -187,7 +187,7 @@ public:
/// getEnableTailMergeDefault - the default setting for -enable-tail-merge
/// on this target. User flag overrides.
virtual const bool getEnableTailMergeDefault() const { return false; }
virtual const bool getEnableTailMergeDefault() const { return true; }
/// addPassesToEmitFile - Add passes to the specified pass manager to get the
/// specified file emitted. Typically this will involve several steps of code
@ -322,7 +322,7 @@ public:
/// getEnableTailMergeDefault - the default setting for -enable-tail-merge
/// on this target. User flag overrides.
virtual const bool getEnableTailMergeDefault() const { return false; }
virtual const bool getEnableTailMergeDefault() const { return true; }
};
} // End llvm namespace

17
lib/CodeGen/BranchFolding.cpp
View File

@ -420,6 +420,21 @@ static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB,
TII->InsertBranch(*CurMBB, SuccBB, NULL, std::vector<MachineOperand>());
}
static bool MergeCompare(std::pair<unsigned,MachineBasicBlock*> p,
std::pair<unsigned,MachineBasicBlock*> q) {
if (p.first < q.first)
return true;
else if (p.first > q.first)
return false;
else if (p.second->getNumber() < q.second->getNumber())
return true;
else if (p.second->getNumber() > q.second->getNumber())
return false;
else
assert(0 && "Predecessor appears twice");
}
// See if any of the blocks in MergePotentials (which all have a common single
// successor, or all have no successor) can be tail-merged. If there is a
// successor, any blocks in MergePotentials that are not tail-merged and
@ -435,7 +450,7 @@ bool BranchFolder::TryMergeBlocks(MachineBasicBlock *SuccBB,
// Sort by hash value so that blocks with identical end sequences sort
// together.
std::stable_sort(MergePotentials.begin(), MergePotentials.end());
std::stable_sort(MergePotentials.begin(), MergePotentials.end(), MergeCompare);
// Walk through equivalence sets looking for actual exact matches.
while (MergePotentials.size() > 1) {