[AMDGPU] Fix crash due to missing check for FLAT instructions that dont use vector registers when computing VALU hazard (#123627)

Author: chinmaydd

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp

@@ -858,9 +858,12 @@ int GCNHazardRecognizer::createsVALUHazard(const MachineInstr &MI) {
   }
 
   if (TII->isFLAT(MI)) {
-    int DataIdx = AMDGPU::getNamedOperandIdx(Opcode, AMDGPU::OpName::vdata);
-    if (AMDGPU::getRegBitWidth(Desc.operands()[DataIdx].RegClass) > 64)
-      return DataIdx;
+    // There is no hazard if the instruction does not use vector regs
+    if (VDataIdx == -1)
+      return -1;
+
+    if (AMDGPU::getRegBitWidth(VDataRCID) > 64)
+      return VDataIdx;
   }
 
   return -1;

llvm/test/CodeGen/AMDGPU/fix-crash-valu-hazard.ll

@@ -0,0 +1,67 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgcn -mcpu=gfx942 < %s | FileCheck -check-prefix=GFX942 %s
+; RUN: llc -mtriple=amdgcn -mcpu=gfx90a -O0 < %s | FileCheck -check-prefix=GFX90A %s
+
+@G = addrspace(1) global <2 x i32> splat (i32 5)
+
+define amdgpu_ps void @global_load_lds_dword_saddr(ptr addrspace(1) inreg nocapture %gptr, ptr addrspace(3) nocapture %lptr) {
+; GFX942-LABEL: global_load_lds_dword_saddr:
+; GFX942:       ; %bb.0: ; %main_body
+; GFX942-NEXT:    v_readfirstlane_b32 s2, v0
+; GFX942-NEXT:    v_mov_b32_e32 v2, 0
+; GFX942-NEXT:    s_mov_b32 m0, s2
+; GFX942-NEXT:    s_nop 0
+; GFX942-NEXT:    global_load_lds_dword v2, s[0:1] offset:32 nt
+; GFX942-NEXT:    s_getpc_b64 s[0:1]
+; GFX942-NEXT:    s_add_u32 s0, s0, G@gotpcrel32@lo+4
+; GFX942-NEXT:    s_addc_u32 s1, s1, G@gotpcrel32@hi+12
+; GFX942-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x0
+; GFX942-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX942-NEXT:    s_load_dwordx2 s[2:3], s[0:1], 0x0
+; GFX942-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX942-NEXT:    s_mul_i32 s3, s3, 10
+; GFX942-NEXT:    s_mul_i32 s2, s2, 10
+; GFX942-NEXT:    v_mov_b32_e32 v0, s2
+; GFX942-NEXT:    v_mov_b32_e32 v1, s3
+; GFX942-NEXT:    global_store_dwordx2 v2, v[0:1], s[0:1]
+; GFX942-NEXT:    s_endpgm
+;
+; GFX90A-LABEL: global_load_lds_dword_saddr:
+; GFX90A:       ; %bb.0: ; %main_body
+; GFX90A-NEXT:    v_mov_b32_e32 v1, v0
+; GFX90A-NEXT:    s_mov_b32 s2, s0
+; GFX90A-NEXT:    ; kill: def $sgpr2 killed $sgpr2 def $sgpr2_sgpr3
+; GFX90A-NEXT:    s_mov_b32 s3, s1
+; GFX90A-NEXT:    ; kill: def $sgpr0_sgpr1 killed $sgpr2_sgpr3
+; GFX90A-NEXT:    s_getpc_b64 s[0:1]
+; GFX90A-NEXT:    s_add_u32 s0, s0, G@gotpcrel32@lo+4
+; GFX90A-NEXT:    s_addc_u32 s1, s1, G@gotpcrel32@hi+12
+; GFX90A-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x0
+; GFX90A-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX90A-NEXT:    s_load_dwordx2 s[8:9], s[0:1], 0x0
+; GFX90A-NEXT:    v_mov_b32_e32 v0, 0
+; GFX90A-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX90A-NEXT:    s_mov_b32 s4, s9
+; GFX90A-NEXT:    s_mov_b32 s6, 10
+; GFX90A-NEXT:    s_mul_i32 s4, s4, s6
+; GFX90A-NEXT:    s_mov_b32 s5, s8
+; GFX90A-NEXT:    s_mul_i32 s5, s5, s6
+; GFX90A-NEXT:    v_mov_b32_e32 v2, s5
+; GFX90A-NEXT:    v_mov_b32_e32 v4, s4
+; GFX90A-NEXT:    ; kill: def $vgpr2 killed $vgpr2 def $vgpr2_vgpr3 killed $exec
+; GFX90A-NEXT:    v_mov_b32_e32 v3, v4
+; GFX90A-NEXT:    ; implicit-def: $sgpr4
+; GFX90A-NEXT:    v_readfirstlane_b32 s4, v1
+; GFX90A-NEXT:    s_mov_b32 m0, s4
+; GFX90A-NEXT:    s_nop 0
+; GFX90A-NEXT:    global_load_dword v0, s[2:3] offset:32 slc lds
+; GFX90A-NEXT:    s_waitcnt lgkmcnt(0)
+; GFX90A-NEXT:    global_store_dwordx2 v0, v[2:3], s[0:1]
+; GFX90A-NEXT:    s_endpgm
+main_body:
+  %LGV = load <2 x i32>, ptr addrspace(1) @G, align 8
+  %B = mul <2 x i32> %LGV, splat (i32 10)
+  call void @llvm.amdgcn.global.load.lds(ptr addrspace(1) %gptr, ptr addrspace(3) %lptr, i32 4, i32 32, i32 2)
+  store <2 x i32> %B, ptr addrspace(1) @G, align 8
+  ret void
+}

llvm/test/CodeGen/AMDGPU/hazard-flat-instruction-valu-check.mir

@@ -0,0 +1,20 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc -mtriple=amdgcn -mcpu=gfx942 -verify-machineinstrs -run-pass=post-RA-hazard-rec %s -o - | FileCheck -check-prefix=GCN %s
+
+---
+name:            test_flat_valu_hazard
+noVRegs:         true
+body:             |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; GCN-LABEL: name: test_flat_valu_hazard
+    ; GCN: liveins: $vgpr0, $vgpr1
+    ; GCN-NEXT: {{  $}}
+    ; GCN-NEXT: GLOBAL_LOAD_LDS_DWORD_SADDR killed $sgpr0_sgpr1, killed $vgpr0, 32, 2, implicit $m0, implicit $exec
+    ; GCN-NEXT: $vgpr0 = V_MOV_B32_e32 killed $vgpr1, implicit $exec, implicit $exec
+    ; GCN-NEXT: FLAT_STORE_DWORDX2 killed renamable $vgpr2_vgpr3, killed renamable $vgpr0_vgpr1, 0, 0, implicit $exec, implicit $flat_scr
+    GLOBAL_LOAD_LDS_DWORD_SADDR killed $sgpr0_sgpr1, killed $vgpr0, 32, 2, implicit $m0, implicit $exec
+    $vgpr0 = V_MOV_B32_e32 killed $vgpr1, implicit $exec, implicit $exec
+    FLAT_STORE_DWORDX2 killed renamable $vgpr2_vgpr3, killed renamable $vgpr0_vgpr1, 0, 0, implicit $exec, implicit $flat_scr
+...