[llvm] f383c53 - [MachineSink] Compile time improvement for large testcases which has many kill flags

[Bing1 Yu via llvm-commits]

Author: Bing1 Yu
Date: 2021-10-18T15:44:07+08:00
New Revision: f383c533110664d41df51b08637df7243c4d6bf7

URL: https://github.com/llvm/llvm-project/commit/f383c533110664d41df51b08637df7243c4d6bf7
DIFF: https://github.com/llvm/llvm-project/commit/f383c533110664d41df51b08637df7243c4d6bf7.diff

LOG: [MachineSink] Compile time improvement for large testcases which has many kill flags

We did a experiment and observed dramatic decrease on compilation time which spent on clearing kill flags.
Before:
Number of BasicBlocks:33357
Number of Instructions:162067
Number of Cleared Kill Flags:32869
Time of handling kill flags(ms):1.607509e+05

After:
Number of BasicBlocks:33357
Number of Instructions:162067
Number of Cleared Kill Flags:32869
Time of handling kill flags:3.987371e+03

Reviewed By: MatzeB

Differential Revision: https://reviews.llvm.org/D111688

Added: 
    

Modified: 
    llvm/lib/CodeGen/MachineSink.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
index ec98394dca79..b570732ed990 100644
--- a/llvm/lib/CodeGen/MachineSink.cpp
+++ b/llvm/lib/CodeGen/MachineSink.cpp
@@ -131,7 +131,7 @@ namespace {
     // will be split.
     SetVector<std::pair<MachineBasicBlock *, MachineBasicBlock *>> ToSplit;
 
-    SparseBitVector<> RegsToClearKillFlags;
+    DenseSet<Register> RegsToClearKillFlags;
 
     using AllSuccsCache =
         std::map<MachineBasicBlock *, SmallVector<MachineBasicBlock *, 4>>;
@@ -1439,7 +1439,7 @@ bool MachineSinking::SinkInstruction(MachineInstr &MI, bool &SawStore,
   // used registers.
   for (MachineOperand &MO : MI.operands()) {
     if (MO.isReg() && MO.isUse())
-      RegsToClearKillFlags.set(MO.getReg()); // Remember to clear kill flags.
+      RegsToClearKillFlags.insert(MO.getReg()); // Remember to clear kill flags.
   }
 
   return true;