[llvm-branch-commits] [llvm] AMDGPU: Stop using aligned VGPR classes for addRegisterClass (PR #158278)
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Fri Sep 12 04:53:59 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu
Author: Matt Arsenault (arsenm)
<details>
<summary>Changes</summary>
This is unnecessary. At use emission time, InstrEmitter will
use the common subclass of the value type's register class and
the use instruction register classes. This removes one of the
obstacles to treating special case instructions that do not have
the alignment requirement overly conservatively.
---
Full diff: https://github.com/llvm/llvm-project/pull/158278.diff
2 Files Affected:
- (modified) llvm/lib/Target/AMDGPU/SIISelLowering.cpp (+16-16)
- (modified) llvm/test/CodeGen/AMDGPU/mfma-loop.ll (+8-6)
``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 4927d2be67590..b0f5eb09a0116 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -110,52 +110,52 @@ SITargetLowering::SITargetLowering(const TargetMachine &TM,
addRegisterClass(MVT::Untyped, V64RegClass);
addRegisterClass(MVT::v3i32, &AMDGPU::SGPR_96RegClass);
- addRegisterClass(MVT::v3f32, TRI->getVGPRClassForBitWidth(96));
+ addRegisterClass(MVT::v3f32, &AMDGPU::VReg_96RegClass);
addRegisterClass(MVT::v2i64, &AMDGPU::SGPR_128RegClass);
addRegisterClass(MVT::v2f64, &AMDGPU::SGPR_128RegClass);
addRegisterClass(MVT::v4i32, &AMDGPU::SGPR_128RegClass);
- addRegisterClass(MVT::v4f32, TRI->getVGPRClassForBitWidth(128));
+ addRegisterClass(MVT::v4f32, &AMDGPU::VReg_128RegClass);
addRegisterClass(MVT::v5i32, &AMDGPU::SGPR_160RegClass);
- addRegisterClass(MVT::v5f32, TRI->getVGPRClassForBitWidth(160));
+ addRegisterClass(MVT::v5f32, &AMDGPU::VReg_160RegClass);
addRegisterClass(MVT::v6i32, &AMDGPU::SGPR_192RegClass);
- addRegisterClass(MVT::v6f32, TRI->getVGPRClassForBitWidth(192));
+ addRegisterClass(MVT::v6f32, &AMDGPU::VReg_192RegClass);
addRegisterClass(MVT::v3i64, &AMDGPU::SGPR_192RegClass);
- addRegisterClass(MVT::v3f64, TRI->getVGPRClassForBitWidth(192));
+ addRegisterClass(MVT::v3f64, &AMDGPU::VReg_192RegClass);
addRegisterClass(MVT::v7i32, &AMDGPU::SGPR_224RegClass);
- addRegisterClass(MVT::v7f32, TRI->getVGPRClassForBitWidth(224));
+ addRegisterClass(MVT::v7f32, &AMDGPU::VReg_224RegClass);
addRegisterClass(MVT::v8i32, &AMDGPU::SGPR_256RegClass);
- addRegisterClass(MVT::v8f32, TRI->getVGPRClassForBitWidth(256));
+ addRegisterClass(MVT::v8f32, &AMDGPU::VReg_256RegClass);
addRegisterClass(MVT::v4i64, &AMDGPU::SGPR_256RegClass);
- addRegisterClass(MVT::v4f64, TRI->getVGPRClassForBitWidth(256));
+ addRegisterClass(MVT::v4f64, &AMDGPU::VReg_256RegClass);
addRegisterClass(MVT::v9i32, &AMDGPU::SGPR_288RegClass);
- addRegisterClass(MVT::v9f32, TRI->getVGPRClassForBitWidth(288));
+ addRegisterClass(MVT::v9f32, &AMDGPU::VReg_288RegClass);
addRegisterClass(MVT::v10i32, &AMDGPU::SGPR_320RegClass);
- addRegisterClass(MVT::v10f32, TRI->getVGPRClassForBitWidth(320));
+ addRegisterClass(MVT::v10f32, &AMDGPU::VReg_320RegClass);
addRegisterClass(MVT::v11i32, &AMDGPU::SGPR_352RegClass);
- addRegisterClass(MVT::v11f32, TRI->getVGPRClassForBitWidth(352));
+ addRegisterClass(MVT::v11f32, &AMDGPU::VReg_352RegClass);
addRegisterClass(MVT::v12i32, &AMDGPU::SGPR_384RegClass);
- addRegisterClass(MVT::v12f32, TRI->getVGPRClassForBitWidth(384));
+ addRegisterClass(MVT::v12f32, &AMDGPU::VReg_384RegClass);
addRegisterClass(MVT::v16i32, &AMDGPU::SGPR_512RegClass);
- addRegisterClass(MVT::v16f32, TRI->getVGPRClassForBitWidth(512));
+ addRegisterClass(MVT::v16f32, &AMDGPU::VReg_512RegClass);
addRegisterClass(MVT::v8i64, &AMDGPU::SGPR_512RegClass);
- addRegisterClass(MVT::v8f64, TRI->getVGPRClassForBitWidth(512));
+ addRegisterClass(MVT::v8f64, &AMDGPU::VReg_512RegClass);
addRegisterClass(MVT::v16i64, &AMDGPU::SGPR_1024RegClass);
- addRegisterClass(MVT::v16f64, TRI->getVGPRClassForBitWidth(1024));
+ addRegisterClass(MVT::v16f64, &AMDGPU::VReg_1024RegClass);
if (Subtarget->has16BitInsts()) {
if (Subtarget->useRealTrue16Insts()) {
@@ -187,7 +187,7 @@ SITargetLowering::SITargetLowering(const TargetMachine &TM,
}
addRegisterClass(MVT::v32i32, &AMDGPU::VReg_1024RegClass);
- addRegisterClass(MVT::v32f32, TRI->getVGPRClassForBitWidth(1024));
+ addRegisterClass(MVT::v32f32, &AMDGPU::VReg_1024RegClass);
computeRegisterProperties(Subtarget->getRegisterInfo());
diff --git a/llvm/test/CodeGen/AMDGPU/mfma-loop.ll b/llvm/test/CodeGen/AMDGPU/mfma-loop.ll
index d39daaade677f..3657a6b1b7415 100644
--- a/llvm/test/CodeGen/AMDGPU/mfma-loop.ll
+++ b/llvm/test/CodeGen/AMDGPU/mfma-loop.ll
@@ -2430,8 +2430,9 @@ define amdgpu_kernel void @test_mfma_nested_loop_zeroinit(ptr addrspace(1) %arg)
; GFX90A-NEXT: v_accvgpr_mov_b32 a29, a0
; GFX90A-NEXT: v_accvgpr_mov_b32 a30, a0
; GFX90A-NEXT: v_accvgpr_mov_b32 a31, a0
-; GFX90A-NEXT: v_mov_b32_e32 v0, 2.0
-; GFX90A-NEXT: v_mov_b32_e32 v1, 1.0
+; GFX90A-NEXT: v_mov_b32_e32 v0, 1.0
+; GFX90A-NEXT: v_mov_b32_e32 v1, 2.0
+; GFX90A-NEXT: ; kill: def $agpr0_agpr1_agpr2_agpr3_agpr4_agpr5_agpr6_agpr7_agpr8_agpr9_agpr10_agpr11_agpr12_agpr13_agpr14_agpr15_agpr16_agpr17_agpr18_agpr19_agpr20_agpr21_agpr22_agpr23_agpr24_agpr25_agpr26_agpr27_agpr28_agpr29_agpr30_agpr31 killed $agpr0_agpr1_agpr2_agpr3_agpr4_agpr5_agpr6_agpr7_agpr8_agpr9_agpr10_agpr11_agpr12_agpr13_agpr14_agpr15_agpr16_agpr17_agpr18_agpr19_agpr20_agpr21_agpr22_agpr23_agpr24_agpr25_agpr26_agpr27_agpr28_agpr29_agpr30_agpr31 killed $exec
; GFX90A-NEXT: .LBB9_1: ; %for.cond.preheader
; GFX90A-NEXT: ; =>This Loop Header: Depth=1
; GFX90A-NEXT: ; Child Loop BB9_2 Depth 2
@@ -2440,7 +2441,7 @@ define amdgpu_kernel void @test_mfma_nested_loop_zeroinit(ptr addrspace(1) %arg)
; GFX90A-NEXT: ; Parent Loop BB9_1 Depth=1
; GFX90A-NEXT: ; => This Inner Loop Header: Depth=2
; GFX90A-NEXT: s_nop 0
-; GFX90A-NEXT: v_mfma_f32_32x32x1f32 a[0:31], v1, v0, a[0:31]
+; GFX90A-NEXT: v_mfma_f32_32x32x1f32 a[0:31], v0, v1, a[0:31]
; GFX90A-NEXT: s_add_i32 s1, s1, -1
; GFX90A-NEXT: s_cmp_lg_u32 s1, 0
; GFX90A-NEXT: s_cbranch_scc1 .LBB9_2
@@ -2500,8 +2501,9 @@ define amdgpu_kernel void @test_mfma_nested_loop_zeroinit(ptr addrspace(1) %arg)
; GFX942-NEXT: v_accvgpr_mov_b32 a29, a0
; GFX942-NEXT: v_accvgpr_mov_b32 a30, a0
; GFX942-NEXT: v_accvgpr_mov_b32 a31, a0
-; GFX942-NEXT: v_mov_b32_e32 v0, 2.0
-; GFX942-NEXT: v_mov_b32_e32 v1, 1.0
+; GFX942-NEXT: v_mov_b32_e32 v0, 1.0
+; GFX942-NEXT: v_mov_b32_e32 v1, 2.0
+; GFX942-NEXT: ; kill: def $agpr0_agpr1_agpr2_agpr3_agpr4_agpr5_agpr6_agpr7_agpr8_agpr9_agpr10_agpr11_agpr12_agpr13_agpr14_agpr15_agpr16_agpr17_agpr18_agpr19_agpr20_agpr21_agpr22_agpr23_agpr24_agpr25_agpr26_agpr27_agpr28_agpr29_agpr30_agpr31 killed $agpr0_agpr1_agpr2_agpr3_agpr4_agpr5_agpr6_agpr7_agpr8_agpr9_agpr10_agpr11_agpr12_agpr13_agpr14_agpr15_agpr16_agpr17_agpr18_agpr19_agpr20_agpr21_agpr22_agpr23_agpr24_agpr25_agpr26_agpr27_agpr28_agpr29_agpr30_agpr31 killed $exec
; GFX942-NEXT: .LBB9_1: ; %for.cond.preheader
; GFX942-NEXT: ; =>This Loop Header: Depth=1
; GFX942-NEXT: ; Child Loop BB9_2 Depth 2
@@ -2510,7 +2512,7 @@ define amdgpu_kernel void @test_mfma_nested_loop_zeroinit(ptr addrspace(1) %arg)
; GFX942-NEXT: ; Parent Loop BB9_1 Depth=1
; GFX942-NEXT: ; => This Inner Loop Header: Depth=2
; GFX942-NEXT: s_nop 0
-; GFX942-NEXT: v_mfma_f32_32x32x1_2b_f32 a[0:31], v1, v0, a[0:31]
+; GFX942-NEXT: v_mfma_f32_32x32x1_2b_f32 a[0:31], v0, v1, a[0:31]
; GFX942-NEXT: s_add_i32 s1, s1, -1
; GFX942-NEXT: s_cmp_lg_u32 s1, 0
; GFX942-NEXT: s_cbranch_scc1 .LBB9_2
``````````
</details>
https://github.com/llvm/llvm-project/pull/158278
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