[llvm] AMDGPU: Fix crash in rewrite AGPR copy MFMA pass on dead valnos (PR #153915)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 15 19:40:16 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu
Author: Matt Arsenault (arsenm)
<details>
<summary>Changes</summary>
Test isn't great, probably won't reliably reproduce the problem
in the future.
---
Full diff: https://github.com/llvm/llvm-project/pull/153915.diff
2 Files Affected:
- (modified) llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp (+3)
- (added) llvm/test/CodeGen/AMDGPU/av-split-dead-valno-crash.ll (+211)
``````````diff
diff --git a/llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp b/llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp
index bab83483f3de1..20b5fd94aba94 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURewriteAGPRCopyMFMA.cpp
@@ -147,6 +147,9 @@ bool AMDGPURewriteAGPRCopyMFMAImpl::run(MachineFunction &MF) const {
// TODO: Test multiple uses
for (VNInfo *VNI : LI.vnis()) {
+ if (VNI->isPHIDef() || VNI->isUnused())
+ continue;
+
MachineInstr *DefMI = LIS.getInstructionFromIndex(VNI->def);
// TODO: Handle SplitKit produced copy bundles for partially defined
diff --git a/llvm/test/CodeGen/AMDGPU/av-split-dead-valno-crash.ll b/llvm/test/CodeGen/AMDGPU/av-split-dead-valno-crash.ll
new file mode 100644
index 0000000000000..89fe0ab526a8a
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/av-split-dead-valno-crash.ll
@@ -0,0 +1,211 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx942 -stress-regalloc=18 < %s | FileCheck %s
+
+define amdgpu_kernel void @vgpr_mfma_pass_av_split_crash(double %arg1, i1 %arg2, i1 %cond.i.i.i2295, ptr addrspace(1) %ptr, ptr %ptr1) #0 {
+; CHECK-LABEL: vgpr_mfma_pass_av_split_crash:
+; CHECK: ; %bb.0: ; %entry
+; CHECK-NEXT: s_load_dword s0, s[4:5], 0x8
+; CHECK-NEXT: s_load_dwordx2 s[10:11], s[4:5], 0x0
+; CHECK-NEXT: s_load_dwordx4 s[12:15], s[4:5], 0x10
+; CHECK-NEXT: v_mov_b32_e32 v1, 0x3e21eeb6
+; CHECK-NEXT: v_mov_b32_e32 v2, 0xa17f65f6
+; CHECK-NEXT: s_waitcnt lgkmcnt(0)
+; CHECK-NEXT: s_bitcmp1_b32 s0, 0
+; CHECK-NEXT: s_cselect_b64 s[16:17], -1, 0
+; CHECK-NEXT: s_xor_b64 s[18:19], s[16:17], -1
+; CHECK-NEXT: s_bitcmp1_b32 s0, 8
+; CHECK-NEXT: s_cselect_b64 s[2:3], -1, 0
+; CHECK-NEXT: v_cndmask_b32_e64 v0, 0, 1, s[2:3]
+; CHECK-NEXT: s_xor_b64 s[20:21], s[2:3], -1
+; CHECK-NEXT: v_cmp_ne_u32_e64 s[0:1], 1, v0
+; CHECK-NEXT: s_and_b64 s[2:3], exec, s[2:3]
+; CHECK-NEXT: v_mov_b32_e32 v0, 0x9037ab78
+; CHECK-NEXT: v_mov_b32_e32 v3, 0xbe927e4f
+; CHECK-NEXT: v_mov_b32_e32 v4, 0x19f4ec90
+; CHECK-NEXT: v_mov_b32_e32 v5, 0x3efa01a0
+; CHECK-NEXT: v_mov_b32_e32 v6, 0x16c16967
+; CHECK-NEXT: v_mov_b32_e32 v7, 0xbf56c16c
+; CHECK-NEXT: v_mov_b32_e32 v8, 0x69efb384
+; CHECK-NEXT: v_mov_b32_e32 v9, 0x3f4b2bb0
+; CHECK-NEXT: v_mov_b32_e32 v10, 0xa57d9582
+; CHECK-NEXT: v_mov_b32_e32 v11, 0xbf8c6ea4
+; CHECK-NEXT: v_mov_b32_e32 v12, 0xe82d3ff0
+; CHECK-NEXT: v_mov_b32_e32 v13, 0xbfa59976
+; CHECK-NEXT: v_mov_b32_e32 v14, 0x8427b883
+; CHECK-NEXT: v_mov_b32_e32 v15, 0x3fae1bb4
+; CHECK-NEXT: s_mov_b64 s[22:23], 0
+; CHECK-NEXT: v_mov_b32_e32 v16, 0x57b87036
+; CHECK-NEXT: v_mov_b32_e32 v17, 0x3fb3b136
+; CHECK-NEXT: s_and_b64 s[4:5], exec, s[16:17]
+; CHECK-NEXT: v_mov_b32_e32 v18, 0x55555523
+; CHECK-NEXT: v_mov_b32_e32 v19, 0xbfd55555
+; CHECK-NEXT: s_and_b64 s[6:7], exec, s[18:19]
+; CHECK-NEXT: v_mov_b32_e32 v20, 0
+; CHECK-NEXT: ; implicit-def: $agpr0_agpr1
+; CHECK-NEXT: ; implicit-def: $vgpr22_vgpr23
+; CHECK-NEXT: s_branch .LBB0_2
+; CHECK-NEXT: .LBB0_1: ; %Flow9
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: s_andn2_b64 vcc, exec, s[24:25]
+; CHECK-NEXT: s_cbranch_vccz .LBB0_17
+; CHECK-NEXT: .LBB0_2: ; %._crit_edge1942.i.i.i3548
+; CHECK-NEXT: ; =>This Loop Header: Depth=1
+; CHECK-NEXT: ; Child Loop BB0_6 Depth 2
+; CHECK-NEXT: s_and_b64 vcc, exec, s[0:1]
+; CHECK-NEXT: s_cbranch_vccnz .LBB0_9
+; CHECK-NEXT: ; %bb.3: ; %.preheader1868.i.i.i3244
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: s_mov_b64 vcc, s[4:5]
+; CHECK-NEXT: s_cbranch_vccz .LBB0_10
+; CHECK-NEXT: ; %bb.4: ; %.preheader1855.i.i.i3329.preheader
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_mov_b64_e32 v[24:25], s[14:15]
+; CHECK-NEXT: flat_load_dwordx2 v[24:25], v[24:25]
+; CHECK-NEXT: v_mov_b64_e32 v[26:27], v[0:1]
+; CHECK-NEXT: v_mov_b64_e32 v[28:29], v[2:3]
+; CHECK-NEXT: v_mov_b64_e32 v[30:31], v[16:17]
+; CHECK-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
+; CHECK-NEXT: v_fmac_f64_e32 v[26:27], 0, v[24:25]
+; CHECK-NEXT: v_fmac_f64_e32 v[28:29], 0, v[26:27]
+; CHECK-NEXT: v_mov_b64_e32 v[26:27], v[4:5]
+; CHECK-NEXT: v_fmac_f64_e32 v[26:27], 0, v[28:29]
+; CHECK-NEXT: v_mov_b64_e32 v[28:29], v[6:7]
+; CHECK-NEXT: v_fmac_f64_e32 v[28:29], 0, v[26:27]
+; CHECK-NEXT: v_mov_b64_e32 v[26:27], v[8:9]
+; CHECK-NEXT: v_fmac_f64_e32 v[26:27], 0, v[28:29]
+; CHECK-NEXT: v_mov_b64_e32 v[28:29], v[10:11]
+; CHECK-NEXT: v_fmac_f64_e32 v[28:29], 0, v[26:27]
+; CHECK-NEXT: v_mov_b64_e32 v[26:27], v[12:13]
+; CHECK-NEXT: v_fmac_f64_e32 v[26:27], 0, v[28:29]
+; CHECK-NEXT: v_mov_b64_e32 v[28:29], v[14:15]
+; CHECK-NEXT: v_fmac_f64_e32 v[28:29], 0, v[26:27]
+; CHECK-NEXT: v_fmac_f64_e32 v[30:31], 0, v[28:29]
+; CHECK-NEXT: v_mov_b64_e32 v[26:27], v[18:19]
+; CHECK-NEXT: v_fmac_f64_e32 v[26:27], 0, v[30:31]
+; CHECK-NEXT: v_mov_b64_e32 v[30:31], 0
+; CHECK-NEXT: s_branch .LBB0_6
+; CHECK-NEXT: .LBB0_5: ; %Flow
+; CHECK-NEXT: ; in Loop: Header=BB0_6 Depth=2
+; CHECK-NEXT: s_and_b64 vcc, exec, s[8:9]
+; CHECK-NEXT: s_cbranch_vccnz .LBB0_11
+; CHECK-NEXT: .LBB0_6: ; %.preheader1855.i.i.i3329
+; CHECK-NEXT: ; Parent Loop BB0_2 Depth=1
+; CHECK-NEXT: ; => This Inner Loop Header: Depth=2
+; CHECK-NEXT: v_mov_b64_e32 v[28:29], v[30:31]
+; CHECK-NEXT: s_mov_b64 s[24:25], -1
+; CHECK-NEXT: s_mov_b64 s[8:9], -1
+; CHECK-NEXT: s_mov_b64 vcc, s[2:3]
+; CHECK-NEXT: ; implicit-def: $vgpr30_vgpr31
+; CHECK-NEXT: s_cbranch_vccz .LBB0_5
+; CHECK-NEXT: ; %bb.7: ; %.lr.ph2070.i.i.i3291
+; CHECK-NEXT: ; in Loop: Header=BB0_6 Depth=2
+; CHECK-NEXT: v_accvgpr_read_b32 v31, a1
+; CHECK-NEXT: v_accvgpr_read_b32 v30, a0
+; CHECK-NEXT: s_mov_b64 s[8:9], s[18:19]
+; CHECK-NEXT: s_mov_b64 vcc, s[6:7]
+; CHECK-NEXT: s_cbranch_vccz .LBB0_5
+; CHECK-NEXT: ; %bb.8: ; %.preheader1856.preheader.i.i.i3325
+; CHECK-NEXT: ; in Loop: Header=BB0_6 Depth=2
+; CHECK-NEXT: s_mov_b64 s[24:25], 0
+; CHECK-NEXT: v_mov_b64_e32 v[30:31], v[26:27]
+; CHECK-NEXT: s_mov_b64 s[8:9], 0
+; CHECK-NEXT: s_branch .LBB0_5
+; CHECK-NEXT: .LBB0_9: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_mov_b64_e32 v[24:25], s[10:11]
+; CHECK-NEXT: v_accvgpr_write_b32 a0, v24
+; CHECK-NEXT: s_mov_b64 s[22:23], 0
+; CHECK-NEXT: v_accvgpr_write_b32 a1, v25
+; CHECK-NEXT: s_mov_b64 s[8:9], s[20:21]
+; CHECK-NEXT: s_branch .LBB0_15
+; CHECK-NEXT: .LBB0_10: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: s_mov_b64 s[8:9], -1
+; CHECK-NEXT: v_mov_b64_e32 v[22:23], 0
+; CHECK-NEXT: s_branch .LBB0_15
+; CHECK-NEXT: .LBB0_11: ; %loop.exit.guard
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: s_and_b64 vcc, exec, s[24:25]
+; CHECK-NEXT: s_cbranch_vccz .LBB0_13
+; CHECK-NEXT: ; %bb.12: ; %._crit_edge2105.i.i.i2330.loopexit
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_cmp_nlg_f64_e64 s[8:9], 0, v[28:29]
+; CHECK-NEXT: v_accvgpr_write_b32 a0, v24
+; CHECK-NEXT: v_cndmask_b32_e64 v23, v23, 0, s[16:17]
+; CHECK-NEXT: v_cndmask_b32_e64 v26, 0, 1, s[8:9]
+; CHECK-NEXT: v_mov_b32_e32 v27, v26
+; CHECK-NEXT: s_and_b64 s[8:9], exec, s[16:17]
+; CHECK-NEXT: v_cndmask_b32_e64 v22, v22, 0, s[16:17]
+; CHECK-NEXT: global_store_dwordx2 v20, v[26:27], s[12:13]
+; CHECK-NEXT: s_cselect_b32 s23, s23, 0
+; CHECK-NEXT: s_cselect_b32 s22, s22, 0
+; CHECK-NEXT: s_mov_b64 s[8:9], -1
+; CHECK-NEXT: s_branch .LBB0_14
+; CHECK-NEXT: .LBB0_13: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_accvgpr_write_b32 a0, v24
+; CHECK-NEXT: s_mov_b64 s[8:9], 0
+; CHECK-NEXT: v_mov_b64_e32 v[22:23], 0
+; CHECK-NEXT: .LBB0_14: ; %Flow6
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_accvgpr_write_b32 a1, v25
+; CHECK-NEXT: .LBB0_15: ; %Flow6
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: s_mov_b64 s[24:25], -1
+; CHECK-NEXT: s_and_b64 vcc, exec, s[8:9]
+; CHECK-NEXT: s_cbranch_vccz .LBB0_1
+; CHECK-NEXT: ; %bb.16: ; %._crit_edge2105.i.i.i2330
+; CHECK-NEXT: ; in Loop: Header=BB0_2 Depth=1
+; CHECK-NEXT: v_mov_b32_e32 v21, v20
+; CHECK-NEXT: s_mov_b64 s[24:25], 0
+; CHECK-NEXT: global_store_dwordx2 v20, v[20:21], s[12:13]
+; CHECK-NEXT: s_branch .LBB0_1
+; CHECK-NEXT: .LBB0_17: ; %DummyReturnBlock
+; CHECK-NEXT: s_endpgm
+entry:
+ br label %._crit_edge1942.i.i.i3548
+
+._crit_edge1942.i.i.i3548: ; preds = %._crit_edge2105.i.i.i2330, %entry
+ %.sroa.02591.0.i.i.i226323 = phi double [ poison, %entry ], [ %.sroa.02591.3.i.i.i2301, %._crit_edge2105.i.i.i2330 ]
+ %.sroa.3.0.i.i.i2270 = phi double [ poison, %entry ], [ %.sroa.3.3.i.i.i2308, %._crit_edge2105.i.i.i2330 ]
+ %.014942244.i.i.i2280 = phi double [ 0.000000e+00, %entry ], [ %.31497.i.i.i2317, %._crit_edge2105.i.i.i2330 ]
+ br i1 %cond.i.i.i2295, label %.preheader1868.i.i.i3244, label %._crit_edge2105.i.i.i2330
+
+.preheader1868.i.i.i3244: ; preds = %._crit_edge1942.i.i.i3548
+ %i = load double, ptr %ptr1, align 8
+ %i3 = call double @llvm.fma.f64(double %i, double 0.000000e+00, double 0x3E21EEB69037AB78)
+ %i4 = call double @llvm.fma.f64(double 0.000000e+00, double %i3, double 0xBE927E4FA17F65F6)
+ %i5 = call double @llvm.fma.f64(double 0.000000e+00, double %i4, double 0x3EFA01A019F4EC90)
+ %i6 = call double @llvm.fma.f64(double 0.000000e+00, double %i5, double 0xBF56C16C16C16967)
+ %spec.select.i.i.i3288 = select i1 %arg2, double 0.000000e+00, double %.sroa.3.0.i.i.i2270
+ br i1 %arg2, label %.preheader1855.i.i.i3329, label %._crit_edge2105.i.i.i2330
+
+.lr.ph2070.i.i.i3291: ; preds = %.preheader1855.i.i.i3329
+ br i1 %arg2, label %.preheader1855.i.i.i3329, label %.preheader1856.preheader.i.i.i3325
+
+.preheader1856.preheader.i.i.i3325: ; preds = %.lr.ph2070.i.i.i3291
+ %i11 = call double @llvm.fma.f64(double 0.000000e+00, double %i6, double 0x3F4B2BB069EFB384)
+ %i14 = call double @llvm.fma.f64(double 0.000000e+00, double %i11, double 0xBF8C6EA4A57D9582)
+ %i18 = call double @llvm.fma.f64(double 0.000000e+00, double %i14, double 0xBFA59976E82D3FF0)
+ %i21 = call double @llvm.fma.f64(double 0.000000e+00, double %i18, double 0x3FAE1BB48427B883)
+ %i23 = call double @llvm.fma.f64(double 0.000000e+00, double %i21, double 0x3FB3B13657B87036)
+ %i28 = call double @llvm.fma.f64(double 0.000000e+00, double %i23, double 0xBFD5555555555523)
+ br label %.preheader1855.i.i.i3329
+
+.preheader1855.i.i.i3329: ; preds = %.preheader1856.preheader.i.i.i3325, %.lr.ph2070.i.i.i3291, %.preheader1868.i.i.i3244
+ %.sroa.02591.4.i.i.i3335 = phi double [ %i28, %.preheader1856.preheader.i.i.i3325 ], [ %.sroa.02591.0.i.i.i226323, %.lr.ph2070.i.i.i3291 ], [ 0.000000e+00, %.preheader1868.i.i.i3244 ]
+ %.21496.ph.i.i.i3348 = select i1 %arg2, double %.014942244.i.i.i2280, double 0.000000e+00
+ %i31 = fcmp one double %.sroa.02591.4.i.i.i3335, 0.000000e+00
+ %i32 = select i1 %i31, <2 x i32> zeroinitializer, <2 x i32> splat (i32 1)
+ store <2 x i32> %i32, ptr addrspace(1) %ptr, align 8
+ br i1 %cond.i.i.i2295, label %.lr.ph2070.i.i.i3291, label %._crit_edge2105.i.i.i2330
+
+._crit_edge2105.i.i.i2330: ; preds = %.preheader1855.i.i.i3329, %.preheader1868.i.i.i3244, %._crit_edge1942.i.i.i3548
+ %.sroa.02591.3.i.i.i2301 = phi double [ %.sroa.02591.0.i.i.i226323, %.preheader1868.i.i.i3244 ], [ %arg1, %._crit_edge1942.i.i.i3548 ], [ %i, %.preheader1855.i.i.i3329 ]
+ %.sroa.3.3.i.i.i2308 = phi double [ 0.000000e+00, %.preheader1868.i.i.i3244 ], [ %.sroa.3.0.i.i.i2270, %._crit_edge1942.i.i.i3548 ], [ %spec.select.i.i.i3288, %.preheader1855.i.i.i3329 ]
+ %.31497.i.i.i2317 = phi double [ %.014942244.i.i.i2280, %.preheader1868.i.i.i3244 ], [ 0.000000e+00, %._crit_edge1942.i.i.i3548 ], [ %.21496.ph.i.i.i3348, %.preheader1855.i.i.i3329 ]
+ store double 0.000000e+00, ptr addrspace(1) %ptr, align 8
+ br label %._crit_edge1942.i.i.i3548
+}
+
+declare double @llvm.fma.f64(double, double, double) #1
+
+attributes #0 = { "amdgpu-waves-per-eu"="8,8" "target-cpu"="gfx942" }
+attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
``````````
</details>
https://github.com/llvm/llvm-project/pull/153915
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