[PATCH] D111688: [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.

[Bing Yu via Phabricator via llvm-commits]

yubing created this revision.
Herald added a subscriber: hiraditya.
yubing requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

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


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D111688

Files:
  llvm/lib/CodeGen/MachineSink.cpp


Index: llvm/lib/CodeGen/MachineSink.cpp
===================================================================
--- llvm/lib/CodeGen/MachineSink.cpp
+++ llvm/lib/CodeGen/MachineSink.cpp
@@ -131,7 +131,7 @@
     // will be split.
     SetVector<std::pair<MachineBasicBlock *, MachineBasicBlock *>> ToSplit;
 
-    SparseBitVector<> RegsToClearKillFlags;
+    DenseMap<MachineInstr *, SparseBitVector<>> RegsToClearKillFlags;
 
     using AllSuccsCache =
         std::map<MachineBasicBlock *, SmallVector<MachineBasicBlock *, 4>>;
@@ -496,8 +496,9 @@
   StoreInstrCache.clear();
 
   // Now clear any kill flags for recorded registers.
-  for (auto I : RegsToClearKillFlags)
-    MRI->clearKillFlags(I);
+  for (auto SBV : RegsToClearKillFlags)
+    for (auto I : SBV.second)
+      MRI->clearKillFlags(I);
   RegsToClearKillFlags.clear();
 
   return EverMadeChange;
@@ -1439,7 +1440,8 @@
   // used registers.
   for (MachineOperand &MO : MI.operands()) {
     if (MO.isReg() && MO.isUse())
-      RegsToClearKillFlags.set(MO.getReg()); // Remember to clear kill flags.
+      RegsToClearKillFlags[&MI].set(
+          MO.getReg()); // Remember to clear kill flags.
   }
 
   return true;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D111688.379250.patch
Type: text/x-patch
Size: 1186 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20211013/aa226f5b/attachment.bin>