1 files changed, 91 insertions, 1 deletions

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index b5bb6a0352f..73913b8376d 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -4774,6 +4774,25 @@ ix86_function_type_abi (const_tree fntype)
   return ix86_abi;
 }
 
+static bool
+ix86_function_ms_hook_prologue (const_tree fntype)
+{
+  if (!TARGET_64BIT)
+    {
+      if (lookup_attribute ("ms_hook_prologue", DECL_ATTRIBUTES (fntype)))
+        {
+          if (decl_function_context (fntype) != NULL_TREE)
+          {
+            error_at (DECL_SOURCE_LOCATION (fntype),
+                "ms_hook_prologue is not compatible with nested function");
+          }
+
+          return true;
+        }
+    }
+  return false;
+}
+
 static enum calling_abi
 ix86_function_abi (const_tree fndecl)
 {
@@ -8295,6 +8314,7 @@ ix86_expand_prologue (void)
   bool pic_reg_used;
   struct ix86_frame frame;
   HOST_WIDE_INT allocate;
+  int gen_frame_pointer = frame_pointer_needed;
 
   ix86_finalize_stack_realign_flags ();
 
@@ -8307,6 +8327,46 @@ ix86_expand_prologue (void)
 
   ix86_compute_frame_layout (&frame);
 
+  if (ix86_function_ms_hook_prologue (current_function_decl))
+    {
+      rtx push, mov;
+
+      /* Make sure the function starts with
+         8b ff     movl.s %edi,%edi
+         55        push   %ebp
+         8b ec     movl.s %esp,%ebp
+
+         This matches the hookable function prologue in Win32 API functions in Microsoft Windows
+         XP Service Pack 2 and newer. Wine uses this to enable Windows apps to hook the Win32 API
+         functions provided by Wine */
+      insn = emit_insn (gen_vswapmov (gen_rtx_REG (SImode, DI_REG), gen_rtx_REG (SImode, DI_REG)));
+      push = emit_insn (gen_push (hard_frame_pointer_rtx));
+      mov = emit_insn (gen_vswapmov (hard_frame_pointer_rtx, stack_pointer_rtx));
+
+      if (frame_pointer_needed && !(crtl->drap_reg && crtl->stack_realign_needed))
+        {
+          /* The push %ebp and movl.s %esp, %ebp already set up the frame pointer. No need to do
+             this again. */
+          gen_frame_pointer = 0;
+          RTX_FRAME_RELATED_P (push) = 1;
+          RTX_FRAME_RELATED_P (mov) = 1;
+          if (ix86_cfa_state->reg == stack_pointer_rtx)
+            {
+              ix86_cfa_state->reg = hard_frame_pointer_rtx;
+            }
+        }
+      else
+        {
+          /* If the frame pointer is not needed, pop %ebp again. This could be optimized for cases where
+             ebp needs to be backed up for some other reason.
+
+             If stack realignment is needed, pop the base pointer again, align the stack, and later
+             regenerate the frame pointer setup. The frame pointer generated by the hook prologue
+             is not aligned, so it can't be used */
+          insn = emit_insn ((*ix86_gen_pop1) (hard_frame_pointer_rtx));
+        }
+    }
+
   /* The first insn of a function that accepts its static chain on the
      stack is to push the register that would be filled in by a direct
      call.  This insn will be skipped by the trampoline.  */
@@ -8378,7 +8438,7 @@ ix86_expand_prologue (void)
   /* Note: AT&T enter does NOT have reversed args.  Enter is probably
      slower on all targets.  Also sdb doesn't like it.  */
 
-  if (frame_pointer_needed)
+  if (gen_frame_pointer)
     {
       insn = emit_insn (gen_push (hard_frame_pointer_rtx));
       RTX_FRAME_RELATED_P (insn) = 1;
@@ -26470,6 +26530,35 @@ ix86_handle_struct_attribute (tree *node, tree name,
   return NULL_TREE;
 }
 
+#include <signal.h>
+
+static tree
+ix86_handle_fndecl_attribute (tree *node, tree name,
+                              tree args ATTRIBUTE_UNUSED,
+                              int flags ATTRIBUTE_UNUSED, bool *no_add_attrs)
+{
+  if (TREE_CODE (*node) != FUNCTION_DECL)
+    {
+      warning (OPT_Wattributes, "%qE attribute only applies to functions",
+               name);
+      *no_add_attrs = true;
+      return NULL_TREE;
+    }
+
+  if (TARGET_64BIT)
+    {
+      warning (OPT_Wattributes, "%qE attribute only available for 32-bit",
+               name);
+      return NULL_TREE;
+    }
+
+#ifndef HAVE_AS_IX86_SWAP
+  sorry ("ms_hook_prologue attribute needs assembler swap suffix support");
+#endif
+
+    return NULL_TREE;
+}
+
 static bool
 ix86_ms_bitfield_layout_p (const_tree record_type)
 {
@@ -29512,6 +29601,7 @@ static const struct attribute_spec ix86_attribute_table[] =
   /* ms_abi and sysv_abi calling convention function attributes.  */
   { "ms_abi", 0, 0, false, true, true, ix86_handle_abi_attribute },
   { "sysv_abi", 0, 0, false, true, true, ix86_handle_abi_attribute },
+  { "ms_hook_prologue", 0, 0, true, false, false, ix86_handle_fndecl_attribute },
   /* End element.  */
   { NULL,        0, 0, false, false, false, NULL }
 };