[llvm] [AMDGPU][True16][CodeGen] fix v_mov_b16_t16 index in folding pass (PR #161764)

[Matt Arsenault via llvm-commits]

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@@ -3435,6 +3435,32 @@ bool SIInstrInfo::isFoldableCopy(const MachineInstr &MI) {
   }
 }
 
+unsigned SIInstrInfo::getFoldableCopySrcIdx(const MachineInstr &MI) {
+  switch (MI.getOpcode()) {
+  case AMDGPU::V_MOV_B16_t16_e32:
+  case AMDGPU::V_MOV_B16_t16_e64:
+    return 2;
+  case AMDGPU::V_MOV_B32_e32:
+  case AMDGPU::V_MOV_B32_e64:
+  case AMDGPU::V_MOV_B64_PSEUDO:
+  case AMDGPU::V_MOV_B64_e32:
+  case AMDGPU::V_MOV_B64_e64:
+  case AMDGPU::S_MOV_B32:
+  case AMDGPU::S_MOV_B64:
+  case AMDGPU::S_MOV_B64_IMM_PSEUDO:
+  case AMDGPU::COPY:
+  case AMDGPU::WWM_COPY:
+  case AMDGPU::V_ACCVGPR_WRITE_B32_e64:
+  case AMDGPU::V_ACCVGPR_READ_B32_e64:
+  case AMDGPU::V_ACCVGPR_MOV_B32:
+  case AMDGPU::AV_MOV_B32_IMM_PSEUDO:
+  case AMDGPU::AV_MOV_B64_IMM_PSEUDO:
+    return 1;
+  default:
+    assert(0 && "MI is not a foldable copy");
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arsenm wrote:

llvm_unreachable 

https://github.com/llvm/llvm-project/pull/161764