* x86-64-tdep.c (x86_64_skip_prologue): Print note when debugging

code without frame pointers.

1 files changed, 19 insertions, 3 deletions

diff --git a/gdb/x86-64-tdep.c b/gdb/x86-64-tdep.c
index cbca04e..f30b85e 100644
--- a/gdb/x86-64-tdep.c
+++ b/gdb/x86-64-tdep.c
@@ -116,6 +116,9 @@ static struct register_info x86_64_register_info_table[] = {
 int x86_64_num_regs = X86_64_NUM_REGS;
 int x86_64_num_gregs = X86_64_NUM_GREGS;
 
+/* Did we already print a note about frame pointer?  */
+int omit_fp_note_printed = 0;
+
 /* Number of bytes of storage in the actual machine representation for
    register REGNO.  */
 int
@@ -811,10 +814,23 @@ x86_64_skip_prologue (CORE_ADDR pc)
 
   read_memory (pc, (char *) prolog_buf, PROLOG_BUFSIZE);
 
-  /* First check, whether pc points to pushq %rbp, movq %rsp,%rbp.  */
-  for (i = 0; i < PROLOG_BUFSIZE; i++)
-    if (prolog_expect[i] != prolog_buf[i])
+  /* First check, whether pc points to pushq %rbp. If not, 
+   * print a recommendation to enable frame pointer.  */
+  if (prolog_expect[0] != prolog_buf[0])
+    {
+      if (!omit_fp_note_printed)
+	{
+	  printf_filtered
+	    ("NOTE: This function doesn't seem to have a valid prologue.\n"
+	     "      Try to add -fno-omit-frame-pointer tou your gcc's CFLAGS.\n");
+	  omit_fp_note_printed++;
+	}
       return pc;
+    }
+  /* Valid prolog continues with movq %rsp,%rbp.  */
+  for (i = 1; i < PROLOG_BUFSIZE; i++)
+    if (prolog_expect[i] != prolog_buf[i])
+      return pc + 1;		/* First instruction after pushq %rbp.  */
 
   v_function = find_pc_function (pc);
   v_sal = find_pc_line (pc, 0);