use subst

Author: OCHyams

llvm/lib/Target/X86/X86FixupSetCC.cpp

@@ -131,15 +131,16 @@ bool X86FixupSetCCPass::runOnMachineFunction(MachineFunction &MF) {
                 ZeroReg);
       }
 
-      MachineInstr *NewMI =
-          BuildMI(*ZExt->getParent(), ZExt, ZExt->getDebugLoc(),
-                  TII->get(X86::INSERT_SUBREG), ZExt->getOperand(0).getReg())
-              .addReg(ZeroReg)
-              .addReg(Reg0)
-              .addImm(X86::sub_8bit);
-      // Copy the debug info instr-ref number from the zext to its replacement.
+      BuildMI(*ZExt->getParent(), ZExt, ZExt->getDebugLoc(),
+              TII->get(X86::INSERT_SUBREG), ZExt->getOperand(0).getReg())
+          .addReg(ZeroReg)
+          .addReg(Reg0)
+          .addImm(X86::sub_8bit);
+
       if (unsigned InstrNum = ZExt->peekDebugInstrNum())
-        NewMI->setDebugInstrNum(InstrNum);
+        ZExt->getParent()->getParent()->makeDebugValueSubstitution(
+            {InstrNum, 0}, {MI.getDebugInstrNum(), 0});
+
       ToErase.push_back(ZExt);
     }
   }

llvm/test/DebugInfo/X86/x86fixupsetcc-debug-instr-num.mir

@@ -3,8 +3,13 @@
 ## Check the debug-isntr-number transfers from MOVZX32rr8
 ## to its replacement INSERT_SUBREG.
 
-# CHECK: %[[#]]:gr32 = INSERT_SUBREG %[[#]], %[[#]], %subreg.sub_8bit,  debug-instr-number 1
-# CHECK-NEXT: DBG_INSTR_REF !4, !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
+# CHECK: debugValueSubstitutions:
+# CHECK:  - { srcinst: 1, srcop: 0, dstinst: 2, dstop: 0, subreg: 0 }
+
+# CHECK: %[[#]]:gr8 = SETCCr 15, implicit $eflags,  debug-instr-number 2
+# CHECK: INSERT_SUBREG
+# CHECK-NOT: debug-instr-number
+# CHECK-NEXT: DBG_INSTR_REF ![[#]], !DIExpression(DW_OP_LLVM_arg, 0), dbg-instr-ref(1, 0)
 
 --- |
   source_filename = "reduced.ll"