diff options
Diffstat (limited to 'lib/CodeGen/RegAllocGreedy.cpp')
| -rw-r--r-- | lib/CodeGen/RegAllocGreedy.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp index 3a4ad620d0..a4f6b682a2 100644 --- a/lib/CodeGen/RegAllocGreedy.cpp +++ b/lib/CodeGen/RegAllocGreedy.cpp @@ -2122,6 +2122,11 @@ unsigned RAGreedy::selectOrSplitImpl(LiveInterval &VirtReg, CSRFirstUse = true; BlockFrequency CSRCost(CSRFirstTimeCost); + // Using a CSR for the first time has a cost because it causes push|pop + // to be added to prologue|epilogue. Splitting a cold section of the live + // range can have lower cost than using the CSR for the first time; + // Spilling a live range in the cold path can have lower cost than using + // the CSR for the first time. if (getStage(VirtReg) == RS_Spill && CSRFirstUse && NewVRegs.empty() && CSRFirstTimeCost > 0 && VirtReg.isSpillable()) { // We choose spill over using the CSR for the first time if the spill cost |