[llvm] [AMDGPU][GlobalISel] Add RegBankLegalize support for G_READSTEADYCOUNTER (PR #163661)

[via llvm-commits]

https://github.com/vangthao95 created https://github.com/llvm/llvm-project/pull/163661

None

>From b9765eff600a8a996a694bcb99fb9a2702dfe634 Mon Sep 17 00:00:00 2001
From: Vang Thao <Vang.Thao at amd.com>
Date: Wed, 15 Oct 2025 19:21:47 -0400
Subject: [PATCH] [AMDGPU][GlobalISel] Add RegBankLegalize support for
 G_READSTEADYCOUNTER

---
 llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp | 2 ++
 llvm/test/CodeGen/AMDGPU/readsteadycounter.ll         | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp b/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp
index bfe2c80c810ef..a67b12a22589c 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURegBankLegalizeRules.cpp
@@ -901,6 +901,8 @@ RegBankLegalizeRules::RegBankLegalizeRules(const GCNSubtarget &_ST,
 
   addRulesForGOpcs({G_ABS}, Standard).Uni(S16, {{Sgpr32Trunc}, {Sgpr32SExt}});
 
+  addRulesForGOpcs({G_READSTEADYCOUNTER}, Standard).Uni(S64, {{Sgpr64}, {}});
+
   bool hasSALUFloat = ST->hasSALUFloatInsts();
 
   addRulesForGOpcs({G_FADD}, Standard)
diff --git a/llvm/test/CodeGen/AMDGPU/readsteadycounter.ll b/llvm/test/CodeGen/AMDGPU/readsteadycounter.ll
index ddbae6493aceb..a95d8c788c34c 100644
--- a/llvm/test/CodeGen/AMDGPU/readsteadycounter.ll
+++ b/llvm/test/CodeGen/AMDGPU/readsteadycounter.ll
@@ -1,8 +1,8 @@
 ; RUN: llc -global-isel=0 -mtriple=amdgcn -mcpu=gfx700 < %s | FileCheck %s -check-prefixes=GCN,GFX700
 ; RUN: llc -global-isel=0 -mtriple=amdgcn -mcpu=gfx900 < %s | FileCheck %s -check-prefixes=GCN,GFX900
-; RUN: llc -global-isel=1 -mtriple=amdgcn -mcpu=gfx900 < %s | FileCheck %s -check-prefixes=GCN,GFX900
+; RUN: llc -global-isel=1 -new-reg-bank-select -mtriple=amdgcn -mcpu=gfx900 < %s | FileCheck %s -check-prefixes=GCN,GFX900
 ; RUN: llc -global-isel=0 -mtriple=amdgcn -mcpu=gfx1100 < %s | FileCheck %s -check-prefixes=GCN,GFX1100
-; RUN: llc -global-isel=1 -mtriple=amdgcn -mcpu=gfx1100 < %s | FileCheck %s -check-prefixes=GCN,GFX1100
+; RUN: llc -global-isel=1 -new-reg-bank-select -mtriple=amdgcn -mcpu=gfx1100 < %s | FileCheck %s -check-prefixes=GCN,GFX1100
 
 declare i64 @llvm.readsteadycounter() #0