[llvm] [win][x64] Various fixes for unwind v2 (PR #154834)

[Daniel Paoliello via llvm-commits]

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@@ -190,8 +196,30 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
         State = FunctionState::FinishedEpilog;
         break;
 
-      case X86::LEA64r:
       case X86::MOV64rr:
+        if (State == FunctionState::InEpilog) {
+          // If the prolog contains a stack allocation, then the first
+          // instruction in the epilog must be to adjust the stack pointer.
+          if (!HasSetFrame)
+            return rejectCurrentFunctionInternalError(
+                MF, Mode,
+                "The epilog is setting frame back, but prolog did not set it");
+          if (PoppedRegCount > 0)
+            return rejectCurrentFunctionInternalError(
+                MF, Mode,
+                "The epilog is setting the frame back after popping "
+                "registers");
+          if (HasStackDealloc)
+            return rejectCurrentFunctionInternalError(
+                MF, Mode,
+                "Cannot set the frame back after the stack "
+                "allocation has been deallocated");
+        } else if (State == FunctionState::FinishedEpilog)
+          return rejectCurrentFunctionInternalError(
+              MF, Mode, "Unexpected mov instruction after the epilog");
+        break;
+
+      case X86::LEA64r:
----------------
dpaoliello wrote:

Only if there was a SetFrame AND a stack alloc, otherwise MOV is used:
https://github.com/llvm/llvm-project/blob/1277a1111d420b244a0e595ad9b74827841b723a/llvm/lib/Target/X86/X86FrameLowering.cpp#L2574-L2597

https://github.com/llvm/llvm-project/pull/154834