[llvm-bugs] [Bug 51713] New: __builtin_frame_address(0) returning RSP for x86_64-windows (instead of RBP)

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51713

            Bug ID: 51713
           Summary: __builtin_frame_address(0) returning RSP for
                    x86_64-windows (instead of RBP)
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: xtkoba at gmail.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org

Created attachment 25219
  --> https://bugs.llvm.org/attachment.cgi?id=25219&action=edit
Repro

$ cat frameaddr.c

void bar(int *n);

void foo(int **p, int n)
{
  __asm__ __volatile__ ("nop");
  *p = __builtin_frame_address(0);
  __asm__ __volatile__ ("nop");
  bar(&n);
}

$ clang --target=x86_64-windows frameaddr.c -c -o - | llvm-objdump -d -

<stdin>:        file format coff-x86-64

Disassembly of section .text:

0000000000000000 <foo>:
       0: 55                            pushq   %rbp
       1: 48 83 ec 30                   subq    $48, %rsp
       5: 48 8d 6c 24 30                leaq    48(%rsp), %rbp
       a: 89 55 fc                      movl    %edx, -4(%rbp)
       d: 48 89 4d f0                   movq    %rcx, -16(%rbp)
      11: 90                            nop
      12: 48 8d 4d d0                   leaq    -48(%rbp), %rcx
      16: 48 8b 45 f0                   movq    -16(%rbp), %rax
      1a: 48 89 08                      movq    %rcx, (%rax)
      1d: 90                            nop
      1e: 48 8d 4d fc                   leaq    -4(%rbp), %rcx
      22: e8 00 00 00 00                callq   0x27 <foo+0x27>
      27: 90                            nop
      28: 48 83 c4 30                   addq    $48, %rsp
      2c: 5d                            popq    %rbp
      2d: c3                            retq

The instruction "leaq -48(%rbp), %rcx" at 0x12 should instead be something like
"movq %rbp, %rcx".

I don't know whether this is expected, but this behavior breaks
__builtin_longjmp for x86_64-windows (PR50142).

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