[llvm] [AMDGPU] Refactor getNonSoftWaitcntOpcode and its callers (PR #77933)

[Jay Foad via llvm-commits]

https://github.com/jayfoad created https://github.com/llvm/llvm-project/pull/77933

This avoids listing all soft waitcnt opcodes in two places
(getNonSoftWaitcntOpcode and isSoftWaitcnt) and avoids the need for
helpers isWaitcnt and isWaitcntVsCnt.


>From 8c489a4bc2d8ab10b64c641f598e27b2b0630a4b Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad at amd.com>
Date: Fri, 12 Jan 2024 13:51:41 +0000
Subject: [PATCH] [AMDGPU] Refactor getNonSoftWaitcntOpcode and its callers

This avoids listing all soft waitcnt opcodes in two places
(getNonSoftWaitcntOpcode and isSoftWaitcnt) and avoids the need for
helpers isWaitcnt and isWaitcntVsCnt.
---
 llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp | 20 +++++++--------
 llvm/lib/Target/AMDGPU/SIInstrInfo.cpp      |  3 +--
 llvm/lib/Target/AMDGPU/SIInstrInfo.h        | 27 +++++----------------
 3 files changed, 17 insertions(+), 33 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
index 1cb1d32707f2d7..a2dbde578fa17e 100644
--- a/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp
@@ -874,11 +874,11 @@ static bool updateOperandIfDifferent(MachineInstr &MI, uint16_t OpName,
 }
 
 bool SIInsertWaitcnts::promoteSoftWaitCnt(MachineInstr *Waitcnt) const {
-  unsigned Opcode = Waitcnt->getOpcode();
-  if (!SIInstrInfo::isSoftWaitcnt(Opcode))
+  unsigned Opcode = SIInstrInfo::getNonSoftWaitcntOpcode(Waitcnt->getOpcode());
+  if (Opcode == Waitcnt->getOpcode())
     return false;
 
-  Waitcnt->setDesc(TII->get(SIInstrInfo::getNonSoftWaitcntOpcode(Opcode)));
+  Waitcnt->setDesc(TII->get(Opcode));
   return true;
 }
 
@@ -898,10 +898,10 @@ bool SIInsertWaitcnts::applyPreexistingWaitcnt(
     if (II.isMetaInstruction())
       continue;
 
-    unsigned Opcode = II.getOpcode();
-    bool IsSoft = SIInstrInfo::isSoftWaitcnt(Opcode);
+    unsigned Opcode = SIInstrInfo::getNonSoftWaitcntOpcode(II.getOpcode());
+    bool IsSoft = Opcode != II.getOpcode();
 
-    if (SIInstrInfo::isWaitcnt(Opcode)) {
+    if (Opcode == AMDGPU::S_WAITCNT) {
       // Update required wait count. If this is a soft waitcnt (= it was added
       // by an earlier pass), it may be entirely removed.
       unsigned IEnc = II.getOperand(0).getImm();
@@ -918,7 +918,7 @@ bool SIInsertWaitcnts::applyPreexistingWaitcnt(
         WaitcntInstr = &II;
 
     } else {
-      assert(SIInstrInfo::isWaitcntVsCnt(Opcode));
+      assert(Opcode == AMDGPU::S_WAITCNT_VSCNT);
       assert(II.getOperand(0).getReg() == AMDGPU::SGPR_NULL);
 
       unsigned OldVSCnt =
@@ -1589,9 +1589,9 @@ bool WaitcntBrackets::merge(const WaitcntBrackets &Other) {
 }
 
 static bool isWaitInstr(MachineInstr &Inst) {
-  auto Opcode = Inst.getOpcode();
-  return SIInstrInfo::isWaitcnt(Opcode) ||
-         (SIInstrInfo::isWaitcntVsCnt(Opcode) && Inst.getOperand(0).isReg() &&
+  unsigned Opcode = SIInstrInfo::getNonSoftWaitcntOpcode(Inst.getOpcode());
+  return Opcode == AMDGPU::S_WAITCNT ||
+         (Opcode == AMDGPU::S_WAITCNT_VSCNT && Inst.getOperand(0).isReg() &&
           Inst.getOperand(0).getReg() == AMDGPU::SGPR_NULL);
 }
 
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index d4c7a457e9aae2..5380f6d1fc88f6 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -9065,8 +9065,7 @@ bool SIInstrInfo::isAsmOnlyOpcode(int MCOp) const {
 }
 
 int SIInstrInfo::pseudoToMCOpcode(int Opcode) const {
-  if (SIInstrInfo::isSoftWaitcnt(Opcode))
-    Opcode = SIInstrInfo::getNonSoftWaitcntOpcode(Opcode);
+  Opcode = SIInstrInfo::getNonSoftWaitcntOpcode(Opcode);
 
   unsigned Gen = subtargetEncodingFamily(ST);
 
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.h b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
index 37ee159362a28c..daef6031dd0748 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.h
@@ -905,29 +905,14 @@ class SIInstrInfo final : public AMDGPUGenInstrInfo {
   }
 
   static unsigned getNonSoftWaitcntOpcode(unsigned Opcode) {
-    if (isWaitcnt(Opcode))
+    switch (Opcode) {
+    case AMDGPU::S_WAITCNT_soft:
       return AMDGPU::S_WAITCNT;
-
-    if (isWaitcntVsCnt(Opcode))
+    case AMDGPU::S_WAITCNT_VSCNT_soft:
       return AMDGPU::S_WAITCNT_VSCNT;
-
-    llvm_unreachable("Expected opcode S_WAITCNT/S_WAITCNT_VSCNT");
-  }
-
-  static bool isWaitcnt(unsigned Opcode) {
-    return Opcode == AMDGPU::S_WAITCNT || Opcode == AMDGPU::S_WAITCNT_soft;
-  }
-
-  static bool isWaitcntVsCnt(unsigned Opcode) {
-    return Opcode == AMDGPU::S_WAITCNT_VSCNT ||
-           Opcode == AMDGPU::S_WAITCNT_VSCNT_soft;
-  }
-
-  // "Soft" waitcnt instructions can be relaxed/optimized out by
-  // SIInsertWaitcnts.
-  static bool isSoftWaitcnt(unsigned Opcode) {
-    return Opcode == AMDGPU::S_WAITCNT_soft ||
-           Opcode == AMDGPU::S_WAITCNT_VSCNT_soft;
+    default:
+      return Opcode;
+    }
   }
 
   bool isVGPRCopy(const MachineInstr &MI) const {