[PATCH] D95273: AMDGPU: Reduce the number of expensive calls in SIFormMemoryClause

[Changpeng Fang via Phabricator via llvm-commits]

cfang updated this revision to Diff 319143.
cfang added a comment.

Fix LIT failures.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95273/new/

https://reviews.llvm.org/D95273

Files:
  llvm/lib/Target/AMDGPU/SIFormMemoryClauses.cpp


Index: llvm/lib/Target/AMDGPU/SIFormMemoryClauses.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIFormMemoryClauses.cpp
+++ llvm/lib/Target/AMDGPU/SIFormMemoryClauses.cpp
@@ -317,6 +317,7 @@
       MF.getFunction(), "amdgpu-max-memory-clause", MaxClause);
 
   for (MachineBasicBlock &MBB : MF) {
+    GCNDownwardRPTracker RPT(*LIS);
     MachineBasicBlock::instr_iterator Next;
     for (auto I = MBB.instr_begin(), E = MBB.instr_end(); I != E; I = Next) {
       MachineInstr &MI = *I;
@@ -327,12 +328,19 @@
       if (!isValidClauseInst(MI, IsVMEM))
         continue;
 
-      RegUse Defs, Uses;
-      GCNDownwardRPTracker RPT(*LIS);
-      RPT.reset(MI);
+      if (!RPT.getNext().isValid())
+        RPT.reset(MI);
+      else { // Advance the state to the current MI.
+        RPT.advance(MachineBasicBlock::const_iterator(MI));
+        RPT.advanceBeforeNext();
+      }
 
-      if (!processRegUses(MI, Defs, Uses, RPT))
+      const GCNRPTracker::LiveRegSet LiveRegsCopy(RPT.getLiveRegs());
+      RegUse Defs, Uses;
+      if (!processRegUses(MI, Defs, Uses, RPT)) {
+        RPT.reset(MI, &LiveRegsCopy);
         continue;
+      }
 
       unsigned Length = 1;
       for ( ; Next != E && Length < FuncMaxClause; ++Next) {
@@ -347,8 +355,10 @@
 
         ++Length;
       }
-      if (Length < 2)
+      if (Length < 2) {
+        RPT.reset(MI, &LiveRegsCopy);
         continue;
+      }
 
       Changed = true;
       MFI->limitOccupancy(LastRecordedOccupancy);
@@ -356,6 +366,9 @@
       auto B = BuildMI(MBB, I, DebugLoc(), TII->get(TargetOpcode::BUNDLE));
       Ind->insertMachineInstrInMaps(*B);
 
+      // Restore the state after processing the bundle.
+      RPT.reset(*B, &LiveRegsCopy);
+
       for (auto BI = I; BI != Next; ++BI) {
         BI->bundleWithPred();
         Ind->removeSingleMachineInstrFromMaps(*BI);


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