[llvm] [AMDGPU] Rewrite GFX12 SGPR hazard handling to dedicated pass (PR #118750)

[Carl Ritson via llvm-commits]

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@@ -3103,274 +3097,6 @@ bool GCNHazardRecognizer::fixVALUMaskWriteHazard(MachineInstr *MI) {
   return true;
 }
 
-// Return the numeric ID 0-63 of an 64b SGPR pair for a given SGPR.
-// i.e. SGPR0 = SGPR0_SGPR1 = 0, SGPR3 = SGPR2_SGPR3 = 1, etc
-static std::optional<unsigned> sgprPairNumber(Register Reg,
-                                              const SIRegisterInfo &TRI) {
-  switch (Reg) {
-  case AMDGPU::M0:
-  case AMDGPU::EXEC:
-  case AMDGPU::EXEC_LO:
-  case AMDGPU::EXEC_HI:
-  case AMDGPU::SGPR_NULL:
-  case AMDGPU::SGPR_NULL64:
-    return {};
-  default:
-    break;
-  }
-  unsigned RegN = TRI.getEncodingValue(Reg);
-  if (RegN > 127)
-    return {};
-  return (RegN >> 1) & 0x3f;
-}
-
-// For VALUReadSGPRHazard: pre-compute a bit vector of all SGPRs used by VALUs.
-void GCNHazardRecognizer::computeVALUHazardSGPRs(MachineFunction *MMF) {
-  assert(MMF == &MF);
-
-  // Assume non-empty vector means it has already been computed.
-  if (!VALUReadHazardSGPRs.empty())
-    return;
-
-  auto CallingConv = MF.getFunction().getCallingConv();
-  bool IsCallFree =
-      AMDGPU::isEntryFunctionCC(CallingConv) && !MF.getFrameInfo().hasCalls();
-
-  // Exhaustive search is only viable in non-caller/callee functions where
-  // VALUs will be exposed to the hazard recognizer.
-  UseVALUReadHazardExhaustiveSearch =
-      IsCallFree && MF.getTarget().getOptLevel() > CodeGenOptLevel::None &&
-      MF.getInstructionCount() <= MaxExhaustiveHazardSearch;
-
-  // Consider all SGPRs hazards if the shader uses function calls or is callee.
-  bool UseVALUUseCache =
-      IsCallFree && MF.getTarget().getOptLevel() > CodeGenOptLevel::None;
-  VALUReadHazardSGPRs.resize(64, !UseVALUUseCache);
-  if (!UseVALUUseCache)
-    return;
-
-  // Perform a post ordered reverse scan to find VALUs which read an SGPR
-  // before a SALU write to the same SGPR.  This provides a reduction in
-  // hazard insertion when all VALU access to an SGPR occurs after its last
-  // SALU write, when compared to a linear scan.
-  const MachineRegisterInfo &MRI = MF.getRegInfo();
-  BitVector SALUWriteSGPRs(64), ReadSGPRs(64);
-  MachineCycleInfo CI;
-  CI.compute(*MMF);
-
-  for (auto *MBB : post_order(&MF)) {
----------------
perlfu wrote:

Done.

https://github.com/llvm/llvm-project/pull/118750