[llvm] 356494c - [NFC][AMDGPU] Perform a single lookup in map in SIInsertWaitcnts::isPreheaderToFlush

[Juan Manuel MARTINEZ CAAMAÑO via llvm-commits]

Author: Juan Manuel MARTINEZ CAAMAÑO
Date: 2023-09-20T14:02:04+02:00
New Revision: 356494c36e716e3bf7820fa4e87ac732b4d87a5a

URL: https://github.com/llvm/llvm-project/commit/356494c36e716e3bf7820fa4e87ac732b4d87a5a
DIFF: https://github.com/llvm/llvm-project/commit/356494c36e716e3bf7820fa4e87ac732b4d87a5a.diff

LOG: [NFC][AMDGPU] Perform a single lookup in map in SIInsertWaitcnts::isPreheaderToFlush

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
index 7358ad9bbc992ce..1628226563e185c 100644
--- a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
@@ -1720,26 +1720,25 @@ bool SIInsertWaitcnts::insertWaitcntInBlock(MachineFunction &MF,
 // which we want to flush the vmcnt counter, and false otherwise.
 bool SIInsertWaitcnts::isPreheaderToFlush(MachineBasicBlock &MBB,
                                           WaitcntBrackets &ScoreBrackets) {
-  if (PreheadersToFlush.count(&MBB))
-    return PreheadersToFlush[&MBB];
-
-  auto UpdateCache = [&](bool val) {
-    PreheadersToFlush[&MBB] = val;
-    return val;
-  };
+  auto [Iterator, IsInserted] = PreheadersToFlush.try_emplace(&MBB, false);
+  if (!IsInserted)
+    return Iterator->second;
 
   MachineBasicBlock *Succ = MBB.getSingleSuccessor();
   if (!Succ)
-    return UpdateCache(false);
+    return false;
 
   MachineLoop *Loop = MLI->getLoopFor(Succ);
   if (!Loop)
-    return UpdateCache(false);
+    return false;
 
-  if (Loop->getLoopPreheader() == &MBB && shouldFlushVmCnt(Loop, ScoreBrackets))
-    return UpdateCache(true);
+  if (Loop->getLoopPreheader() == &MBB &&
+      shouldFlushVmCnt(Loop, ScoreBrackets)) {
+    Iterator->second = true;
+    return true;
+  }
 
-  return UpdateCache(false);
+  return false;
 }
 
 bool SIInsertWaitcnts::isVMEMOrFlatVMEM(const MachineInstr &MI) const {