Alexandre Julliard : msvcrt: Simplify stack layout in __crtCapturePreviousContext().

[Alexandre Julliard]

Module: wine
Branch: master
Commit: ed6aa17d9880f5c5e1fe47fe725bfe96d4ed681f
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=ed6aa17d9880f5c5e1fe47fe725bfe96d4ed681f

Author: Alexandre Julliard <julliard at winehq.org>
Date:   Wed Aug 21 13:54:46 2019 +0200

msvcrt: Simplify stack layout in __crtCapturePreviousContext().

Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 dlls/msvcrt/except_x86_64.c | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/dlls/msvcrt/except_x86_64.c b/dlls/msvcrt/except_x86_64.c
index 1aa04ab..09eddfb 100644
--- a/dlls/msvcrt/except_x86_64.c
+++ b/dlls/msvcrt/except_x86_64.c
@@ -732,9 +732,6 @@ void __cdecl get_prev_context(CONTEXT *ctx, DWORD64 rip)
 
     TRACE("(%p)\n", ctx);
 
-    ctx->Rip = rip;
-    ctx->Rsp += 3*8; /* Rip, Rcx, return address */
-
     rf = RtlLookupFunctionEntry(ctx->Rip, &image_base, NULL);
     if(!rf) {
         FIXME("RtlLookupFunctionEntry failed\n");
@@ -746,16 +743,14 @@ void __cdecl get_prev_context(CONTEXT *ctx, DWORD64 rip)
 }
 
 __ASM_GLOBAL_FUNC( __crtCapturePreviousContext,
-        "pushq (%rsp)\n\t" /* save Rip */
-        __ASM_CFI(".cfi_adjust_cfa_offset 8\n\t")
-        "pushq %rcx\n\t"
-        __ASM_CFI(".cfi_adjust_cfa_offset 8\n\t")
-        "call " __ASM_NAME("RtlCaptureContext") "\n\t"
-        "popq %rcx\n\t"
-        __ASM_CFI(".cfi_adjust_cfa_offset -8\n\t")
-        "popq %rdx\n\t"
-        __ASM_CFI(".cfi_adjust_cfa_offset -8\n\t")
-        "jmp " __ASM_NAME("get_prev_context") );
+                   "movq %rcx,8(%rsp)\n\t"
+                   "call " __ASM_NAME("RtlCaptureContext") "\n\t"
+                   "movq 8(%rsp),%rcx\n\t"     /* context */
+                   "leaq 8(%rsp),%rax\n\t"
+                   "movq %rax,0x98(%rcx)\n\t"  /* context->Rsp */
+                   "movq (%rsp),%rax\n\t"
+                   "movq %rax,0xf8(%rcx)\n\t"  /* context->Rip */
+                   "jmp " __ASM_NAME("get_prev_context") )
 #endif
 
 #endif  /* __x86_64__ */