[AMDGPU] Declutter applyPreexistingWaitcnt()

Declutter applyPreexistingWaitcnt() a little by abstracting the code
that updates the operands to S_WAITCNT and S_WAITCNT_VSCNT instructions
into discrete functions.

Differential Revision: https://reviews.llvm.org/D137624

diff --git a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
index a12fb3a..fe1afda 100644 (file)
--- a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
@@ -842,6 +842,20 @@ FunctionPass *llvm::createSIInsertWaitcntsPass() {
   return new SIInsertWaitcnts();
 }
 
+static bool updateOperandIfDifferent(MachineInstr &MI, uint16_t OpName,
+                                     unsigned NewEnc) {
+  int OpIdx = AMDGPU::getNamedOperandIdx(MI.getOpcode(), OpName);
+  assert(OpIdx >= 0);
+
+  MachineOperand &MO = MI.getOperand(OpIdx);
+
+  if (NewEnc == MO.getImm())
+    return false;
+
+  MO.setImm(NewEnc);
+  return true;
+}
+
 /// Combine consecutive waitcnt instructions that precede \p It and follow
 /// \p OldWaitcntInstr and apply any extra wait from waitcnt that were added
 /// by previous passes. Currently this pass conservatively assumes that these
@@ -897,12 +911,9 @@ bool SIInsertWaitcnts::applyPreexistingWaitcnt(
   // Updated encoding of merged waitcnt with the required wait.
   if (WaitcntInstr) {
     if (Wait.hasWaitExceptVsCnt()) {
-      unsigned NewEnc = AMDGPU::encodeWaitcnt(IV, Wait);
-      unsigned OldEnc = WaitcntInstr->getOperand(0).getImm();
-      if (OldEnc != NewEnc) {
-        WaitcntInstr->getOperand(0).setImm(NewEnc);
-        Modified = true;
-      }
+      Modified |=
+          updateOperandIfDifferent(*WaitcntInstr, AMDGPU::OpName::simm16,
+                                   AMDGPU::encodeWaitcnt(IV, Wait));
       ScoreBrackets.applyWaitcnt(Wait);
       Wait.VmCnt = ~0u;
       Wait.LgkmCnt = ~0u;
@@ -925,14 +936,8 @@ bool SIInsertWaitcnts::applyPreexistingWaitcnt(
   if (WaitcntVsCntInstr) {
     if (Wait.hasWaitVsCnt()) {
       assert(ST->hasVscnt());
-      unsigned OldVSCnt =
-          TII->getNamedOperand(*WaitcntVsCntInstr, AMDGPU::OpName::simm16)
-              ->getImm();
-      if (Wait.VsCnt != OldVSCnt) {
-        TII->getNamedOperand(*WaitcntVsCntInstr, AMDGPU::OpName::simm16)
-            ->setImm(Wait.VsCnt);
-        Modified = true;
-      }
+      Modified |= updateOperandIfDifferent(*WaitcntVsCntInstr,
+                                           AMDGPU::OpName::simm16, Wait.VsCnt);
       ScoreBrackets.applyWaitcnt(Wait);
       Wait.VsCnt = ~0u;