6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-08-09 11:25:55 +00:00
Code Issues Projects Releases Wiki Activity

Don't count PHI instructions toward the limit for tail duplicating a block.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90326 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson
2009-12-02 17:15:24 +00:00
parent 43a8241b65
commit f1e01dcc94
1 changed files with 6 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
lib/CodeGen/TailDuplication.cpp
View File

@@ -129,20 +129,22 @@ bool TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB,
// Check the instructions in the block to determine whether tail-duplication // Check the instructions in the block to determine whether tail-duplication
// is invalid or unlikely to be profitable. // is invalid or unlikely to be profitable.
unsigned i = 0; unsigned InstrCount = 0;
bool HasCall = false; bool HasCall = false;
for (MachineBasicBlock::iterator I = TailBB->begin(); for (MachineBasicBlock::iterator I = TailBB->begin();
I != TailBB->end(); ++I, ++i) { I != TailBB->end(); ++I) {
// Non-duplicable things shouldn't be tail-duplicated. // Non-duplicable things shouldn't be tail-duplicated.
if (I->getDesc().isNotDuplicable()) return false; if (I->getDesc().isNotDuplicable()) return false;
// Don't duplicate more than the threshold. // Don't duplicate more than the threshold.
if (i == MaxDuplicateCount) return false; if (InstrCount == MaxDuplicateCount) return false;
// Remember if we saw a call. // Remember if we saw a call.
if (I->getDesc().isCall()) HasCall = true; if (I->getDesc().isCall()) HasCall = true;
if (I->getOpcode() != TargetInstrInfo::PHI)
InstrCount += 1;
} }
// Heuristically, don't tail-duplicate calls if it would expand code size, // Heuristically, don't tail-duplicate calls if it would expand code size,
// as it's less likely to be worth the extra cost. // as it's less likely to be worth the extra cost.
if (i > 1 && HasCall) if (InstrCount > 1 && HasCall)
return false; return false;
// Iterate through all the unique predecessors and tail-duplicate this // Iterate through all the unique predecessors and tail-duplicate this