[llvm] [AMDGPU] GCNHazardRecognizer: refactor getWaitStatesSince (NFCI) (PR #108347)

[Carl Ritson via llvm-commits]

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@@ -495,51 +496,104 @@ hasHazard(StateT State,
   return false;
 }
 
-// Returns a minimum wait states since \p I walking all predecessors.
-// Only scans until \p IsExpired does not return true.
-// Can only be run in a hazard recognizer mode.
-static int getWaitStatesSince(
+// Update \p WaitStates while iterating from \p I to hazard in \p MBB.
+static HazardFnResult countWaitStatesSince(
     GCNHazardRecognizer::IsHazardFn IsHazard, const MachineBasicBlock *MBB,
-    MachineBasicBlock::const_reverse_instr_iterator I, int WaitStates,
-    IsExpiredFn IsExpired, DenseSet<const MachineBasicBlock *> &Visited,
-    GetNumWaitStatesFn GetNumWaitStates = SIInstrInfo::getNumWaitStates) {
+    MachineBasicBlock::const_reverse_instr_iterator I, int &WaitStates,
+    IsExpiredFn IsExpired, GetNumWaitStatesFn GetNumWaitStates) {
   for (auto E = MBB->instr_rend(); I != E; ++I) {
     // Don't add WaitStates for parent BUNDLE instructions.
     if (I->isBundle())
       continue;
 
     if (IsHazard(*I))
-      return WaitStates;
+      return HazardFound;
 
     if (I->isInlineAsm())
       continue;
 
     WaitStates += GetNumWaitStates(*I);
 
     if (IsExpired(*I, WaitStates))
-      return std::numeric_limits<int>::max();
+      return HazardExpired;
+  }
+
+  return NoHazardFound;
+}
+
+// Implements predecessor search for getWaitStatesSince.
+static int getWaitStatesSinceImpl(
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perlfu wrote:

- Allow renaming of some of the variables to avoid programming errors (on my part).
- Hint the compiler that this is the "out of line" case.

https://github.com/llvm/llvm-project/pull/108347