[AMDGPU] Fix lowering of S_MOV_{B32,B64}_term

[critson]

Summary

If the source of S_MOV_{B32,B64}_term is an immediate then it
cannot be lowered to a COPY.

[arsenm]

llvm/lib/Target/AMDGPU/SIOptimizeExecMasking.cpp

183

!isReg would be more accurate

[arsenm]

Should invert condition and add a check with something more exotic like a global address

[critson]

• Invert condition.
• Add tests against a symbol.

llvm/lib/Target/AMDGPU/SIOptimizeExecMasking.cpp

default:
     return AMDGPU::INSTRUCTION_LIST_END;
   }
 }
 
 // These are only terminators to get correct spill code placement during
 // register allocation, so turn them back into normal instructions.
 static bool removeTerminatorBit(const SIInstrInfo &TII, MachineInstr &MI) {
   switch (MI.getOpcode()) {
-  case AMDGPU::S_MOV_B64_term:
   case AMDGPU::S_MOV_B32_term: {
-    MI.setDesc(TII.get(AMDGPU::COPY));
+    bool ImmSrc = MI.getOperand(1).isImm();
+    MI.setDesc(TII.get(ImmSrc ? AMDGPU::S_MOV_B32 : AMDGPU::COPY));
+    return true;
+  }
+  case AMDGPU::S_MOV_B64_term: {
+    bool ImmSrc = MI.getOperand(1).isImm();
+    MI.setDesc(TII.get(ImmSrc ? AMDGPU::S_MOV_B64 : AMDGPU::COPY));
     return true;
   }
   case AMDGPU::S_XOR_B64_term: {
     // This is only a terminator to get the correct spill code placement during
     // register allocation.
     MI.setDesc(TII.get(AMDGPU::S_XOR_B64));
     return true;
   }

llvm/test/CodeGen/AMDGPU/lower-term-opcodes.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -march=amdgcn -mcpu=gfx1010 -run-pass=si-optimize-exec-masking -verify-machineinstrs  %s -o - | FileCheck %s
+
+---
+name: lower_term_opcodes
+tracksRegLiveness: false
+body: |
+  ; CHECK-LABEL: name: lower_term_opcodes
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   $sgpr0 = COPY $sgpr1
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   $sgpr0 = S_MOV_B32 0
+  ; CHECK: bb.2:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   $sgpr0_sgpr1 = COPY $sgpr2_sgpr3
+  ; CHECK: bb.3:
+  ; CHECK:   successors: %bb.4(0x80000000)
+  ; CHECK:   $sgpr0_sgpr1 = S_MOV_B64 0
+  ; CHECK: bb.4:
+  ; CHECK:   successors: %bb.5(0x80000000)
+  ; CHECK:   $sgpr0 = S_XOR_B32 $sgpr1, $sgpr2, implicit-def $scc
+  ; CHECK: bb.5:
+  ; CHECK:   successors: %bb.6(0x80000000)
+  ; CHECK:   $sgpr0_sgpr1 = S_XOR_B64 $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+  ; CHECK: bb.6:
+  ; CHECK:   successors: %bb.7(0x80000000)
+  ; CHECK:   $sgpr0 = S_OR_B32 $sgpr1, $sgpr2, implicit-def $scc
+  ; CHECK: bb.7:
+  ; CHECK:   successors: %bb.8(0x80000000)
+  ; CHECK:   $sgpr0_sgpr1 = S_OR_B64 $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+  ; CHECK: bb.8:
+  ; CHECK:   successors: %bb.9(0x80000000)
+  ; CHECK:   $sgpr0 = S_ANDN2_B32 $sgpr1, $sgpr2, implicit-def $scc
+  ; CHECK: bb.9:
+  ; CHECK:   $sgpr0_sgpr1 = S_ANDN2_B64 $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+  bb.0:
+    $sgpr0 = S_MOV_B32_term $sgpr1
+
+  bb.1:
+    $sgpr0 = S_MOV_B32_term 0
+
+  bb.2:
+    $sgpr0_sgpr1 = S_MOV_B64_term $sgpr2_sgpr3
+
+  bb.3:
+    $sgpr0_sgpr1 = S_MOV_B64_term 0
+
+  bb.4:
+    $sgpr0 = S_XOR_B32_term $sgpr1, $sgpr2, implicit-def $scc
+
+  bb.5:
+    $sgpr0_sgpr1 = S_XOR_B64_term $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+
+  bb.6:
+    $sgpr0 = S_OR_B32_term $sgpr1, $sgpr2, implicit-def $scc
+
+  bb.7:
+    $sgpr0_sgpr1 = S_OR_B64_term $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+
+  bb.8:
+    $sgpr0 = S_ANDN2_B32_term $sgpr1, $sgpr2, implicit-def $scc
+
+  bb.9:
+    $sgpr0_sgpr1 = S_ANDN2_B64_term $sgpr2_sgpr3, $sgpr2_sgpr3, implicit-def $scc
+...