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Fix PR9398 - 10% of llc compile time is spent in Value::getNumUses. This reduces 

the percentage of time spent in CodeGenPrepare when llcing 403.gcc from 12.6% to
1.8% of total llc time.

llvm-svn: 127069
This commit is contained in:
Cameron Zwarich 2011-03-05 08:12:26 +00:00
parent b8390b7a25
commit 13c885d193
1 changed files with 22 additions and 7 deletions
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21
llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
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@ -569,6 +569,7 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
// are equivalent.
Value *Consensus = 0;
unsigned NumUsesConsensus = 0;
bool IsNumUsesConsensusValid = false;
SmallVector<Instruction*, 16> AddrModeInsts;
ExtAddrMode AddrMode;
while (!worklist.empty()) {
@ -596,16 +597,30 @@ bool CodeGenPrepare::OptimizeMemoryInst(Instruction *MemoryInst, Value *Addr,
AddressingModeMatcher::Match(V, AccessTy,MemoryInst,
NewAddrModeInsts, *TLI);
// This check is broken into two cases with very similar code to avoid using
// getNumUses() as much as possible. Some values have a lot of uses, so
// calling getNumUses() unconditionally caused a significant compile-time
// regression.
if (!Consensus) {
Consensus = V;
AddrMode = NewAddrMode;
AddrModeInsts = NewAddrModeInsts;
continue;
} else if (NewAddrMode == AddrMode) {
if (!IsNumUsesConsensusValid) {
NumUsesConsensus = Consensus->getNumUses();
IsNumUsesConsensusValid = true;
}
// Ensure that the obtained addressing mode is equivalent to that obtained
// for all other roots of the PHI traversal. Also, when choosing one
// such root as representative, select the one with the most uses in order
// to keep the cost modeling heuristics in AddressingModeMatcher applicable.
if (!Consensus || NewAddrMode == AddrMode) {
// to keep the cost modeling heuristics in AddressingModeMatcher
// applicable.
unsigned NumUses = V->getNumUses();
if (NumUses > NumUsesConsensus) {
Consensus = V;
NumUsesConsensus = NumUses;
AddrMode = NewAddrMode;
AddrModeInsts = NewAddrModeInsts;
}
continue;