[llvm-branch-commits] [llvm] [AMDGPU] Update GCNHazardRecognizer's understanding of gfx12 waitcount instructions (PR #153880)

[Stanislav Mekhanoshin via llvm-branch-commits]

https://github.com/rampitec updated 
https://github.com/llvm/llvm-project/pull/153880

>From df0ab0abe2132a729ec1ad18f20faa9b804f0a6f Mon Sep 17 00:00:00 2001
From: Stanislav Mekhanoshin <stanislav.mekhanos...@amd.com>
Date: Fri, 15 Aug 2025 14:10:55 -0700
Subject: [PATCH] [AMDGPU] Update GCNHazardRecognizer's understanding of gfx12
 waitcount instructions

This simply updates the pass's cognizance of these instructions, and for the
most part the hazards where they might be encountered do not exist for gfx12.
Nonetheless, encountering them has to be checked for as doing so would indicate
a compiler error.

Co-authored-by: Stephen Thomas <stephen.tho...@amd.com>
---
 .../lib/Target/AMDGPU/GCNHazardRecognizer.cpp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp 
b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
index c1cca063aac6f..fa3ca27a5f47c 100644
--- a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp
@@ -1357,6 +1357,16 @@ bool 
GCNHazardRecognizer::fixSMEMtoVectorWriteHazards(MachineInstr *MI) {
         // DsCnt corresponds to LGKMCnt here.
         return (Decoded.DsCnt == 0);
       }
+      case AMDGPU::S_WAIT_STORECNT:
+      case AMDGPU::S_WAIT_STORECNT_DSCNT:
+      case AMDGPU::S_WAIT_LOADCNT:
+      case AMDGPU::S_WAIT_LOADCNT_DSCNT:
+      case AMDGPU::S_WAIT_SAMPLECNT:
+      case AMDGPU::S_WAIT_BVHCNT:
+      case AMDGPU::S_WAIT_DSCNT:
+      case AMDGPU::S_WAIT_EXPCNT:
+      case AMDGPU::S_WAIT_KMCNT:
+        llvm_unreachable("unexpected wait count instruction");
       default:
         // SOPP instructions cannot mitigate the hazard.
         if (TII->isSOPP(MI))
@@ -2254,6 +2264,15 @@ int 
GCNHazardRecognizer::checkFPAtomicToDenormModeHazard(MachineInstr *MI) {
     case AMDGPU::S_WAITCNT_EXPCNT:
     case AMDGPU::S_WAITCNT_LGKMCNT:
     case AMDGPU::S_WAIT_IDLE:
+    case AMDGPU::S_WAIT_LOADCNT:
+    case AMDGPU::S_WAIT_LOADCNT_DSCNT:
+    case AMDGPU::S_WAIT_SAMPLECNT:
+    case AMDGPU::S_WAIT_BVHCNT:
+    case AMDGPU::S_WAIT_STORECNT:
+    case AMDGPU::S_WAIT_STORECNT_DSCNT:
+    case AMDGPU::S_WAIT_EXPCNT:
+    case AMDGPU::S_WAIT_DSCNT:
+    case AMDGPU::S_WAIT_KMCNT:
       return true;
     default:
       break;

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