diff options
Diffstat (limited to 'lib/CodeGen/SimpleRegisterCoalescing.cpp')
| -rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.cpp | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index cebf4c9f4a..1a2151fecf 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -987,8 +987,14 @@ SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned SrcReg, LiveInterval &DstInt = li_->getInterval(DstReg); unsigned SrcSize = li_->getApproximateInstructionCount(SrcInt); unsigned DstSize = li_->getApproximateInstructionCount(DstInt); - if (SrcSize <= NewRCCount && DstSize <= NewRCCount) + + // Coalesce aggressively if the intervals are small compared to the number of + // registers in the new class. The number 4 is fairly arbitrary, chosen to be + // less aggressive than the 8 used for the whole function size. + const unsigned ThresSize = 4 * NewRCCount; + if (SrcSize <= ThresSize && DstSize <= ThresSize) return true; + // Estimate *register use density*. If it doubles or more, abort. unsigned SrcUses = std::distance(mri_->use_nodbg_begin(SrcReg), mri_->use_nodbg_end()); @@ -996,12 +1002,12 @@ SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned SrcReg, mri_->use_nodbg_end()); unsigned NewUses = SrcUses + DstUses; unsigned NewSize = SrcSize + DstSize; - if (SrcRC != NewRC && SrcSize > NewRCCount) { + if (SrcRC != NewRC && SrcSize > ThresSize) { unsigned SrcRCCount = allocatableRCRegs_[SrcRC].count(); if (NewUses*SrcSize*SrcRCCount > 2*SrcUses*NewSize*NewRCCount) return false; } - if (DstRC != NewRC && DstSize > NewRCCount) { + if (DstRC != NewRC && DstSize > ThresSize) { unsigned DstRCCount = allocatableRCRegs_[DstRC].count(); if (NewUses*DstSize*DstRCCount > 2*DstUses*NewSize*NewRCCount) return false; |