[win][x64] Permit lea to adjust the stack when using unwind v2 (#154171)

In some cases `leaq` may be used to adjust the stack in an epilog, this
is permitted by unwind v2 and shouldn't raise an error.

Author: dpaoliello

llvm/lib/Target/X86/X86WinEHUnwindV2.cpp

@@ -190,6 +190,7 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
         State = FunctionState::FinishedEpilog;
         break;
 
+      case X86::LEA64r:
       case X86::MOV64rr:
       case X86::ADD64ri32:
         if (State == FunctionState::InEpilog) {
@@ -210,7 +211,8 @@ bool X86WinEHUnwindV2::runOnMachineFunction(MachineFunction &MF) {
           HasStackDealloc = true;
         } else if (State == FunctionState::FinishedEpilog)
           return rejectCurrentFunctionInternalError(
-              MF, Mode, "Unexpected mov or add instruction after the epilog");
+              MF, Mode,
+              "Unexpected lea, mov or add instruction after the epilog");
         break;
 
       case X86::POP64r:

llvm/test/CodeGen/X86/win64-eh-unwindv2-errors.mir

@@ -106,7 +106,7 @@ body:             |
 # RUN:    -x86-wineh-unwindv2-force-mode=1 |  FileCheck %s \
 # RUN:    --check-prefix=BESTEFFORT
 # DEALLOC-AFTER-EPILOG: LLVM ERROR: Windows x64 Unwind v2 is required, but LLVM has generated incompatible code in function 'dealloc_after_epilog':
-# DEALLOC-AFTER-EPILOG-SAME: Unexpected mov or add instruction after the epilog
+# DEALLOC-AFTER-EPILOG-SAME: Unexpected lea, mov or add instruction after the epilog
 
 --- |
   define dso_local void @dealloc_after_epilog() local_unnamed_addr {

llvm/test/CodeGen/X86/win64-eh-unwindv2.ll

@@ -152,6 +152,25 @@ entry:
 ; CHECK-NEXT:   retq
 ; CHECK-NEXT:   .seh_endproc
 
+define dso_local void @large_aligned_alloc() align 16 {
+  %1 = alloca [128 x i8], align 64
+  ret void
+}
+; CHECK-LABEL:  large_aligned_alloc:
+; CHECK:        .seh_unwindversion 2
+; CHECK:        .seh_pushreg %rbp
+; CHECK:        .seh_stackalloc 176
+; CHECK:        .seh_setframe %rbp, 128
+; CHECK:        .seh_endprologue
+; CHECK-NOT:    .seh_endproc
+; CHECK:        .seh_startepilogue
+; CHECK-NEXT:   leaq    48(%rbp), %rsp
+; CHECK-NEXT:   .seh_unwindv2start
+; CHECK-NEXT:   popq    %rbp
+; CHECK-NEXT:   .seh_endepilogue
+; CHECK-NEXT:   retq
+; CHECK-NEXT:   .seh_endproc
+
 declare void @a() local_unnamed_addr
 declare i32 @b() local_unnamed_addr
 declare i32 @c(i32) local_unnamed_addr