[PATCH 1/2] Allow function prologues to have multiple repeating lines

[Alan Hayward]

Compiling gdb.cp/ovldbreak.cc on Ubuntu places two identical line numbers
in the function prologue.

x86_64 Ubtunu 16.04 with GCC 5.4.0-6ubuntu1~16.04.4
000000000040052f <main>:
Line 48
  40052f:	55                   	push   %rbp
  400530:	48 89 e5             	mov    %rsp,%rbp
  400533:	53                   	push   %rbx
  400534:	48 81 ec 88 00 00 00 	sub    $0x88,%rsp
Line 48
  40053b:	64 48 8b 04 25 28 00 	mov    %fs:0x28,%rax
  400542:	00 00
  400544:	48 89 45 e8          	mov    %rax,-0x18(%rbp)
  400548:	31 c0                	xor    %eax,%eax
Line 49
  40054a:	c6 45 85 02          	movb   $0x2,-0x7b(%rbp)
Line 50
  40054e:	c6 45 86 03          	movb   $0x3,-0x7a(%rbp)
etc

Aarch64 Ubuntu 16.04 with GCC 7.2.0-1ubuntu1~16.04
0000000000400708 <main>:
Line 48
  400708:	d102c3ff 	sub	sp, sp, #0xb0
  40070c:	a9027bfd 	stp	x29, x30, [sp,#32]
  400710:	910083fd 	add	x29, sp, #0x20
  400714:	f9001bf3 	str	x19, [sp,#48]
Line 48
  400718:	90000100 	adrp	x0, 420000 <_GLOBAL_OFFSET_TABLE_+0x28>
  40071c:	9100e000 	add	x0, x0, #0x38
  400720:	f9400001 	ldr	x1, [x0]
  400724:	f90047a1 	str	x1, [x29,#136]
  400728:	d2800001 	mov	x1, #0x0                   	// #0
Line 49
  40072c:	52800040 	mov	w0, #0x2                   	// #2
  400730:	3900b7a0 	strb	w0, [x29,#45]
Line 50
  400734:	52800060 	mov	w0, #0x3                   	// #3
  400738:	3900bba0 	strb	w0, [x29,#46]
etc

Compare to openSUSE 13.3 AArch64 with GCC 7.2.1 20171020

00000000004005e4 <main>:
Line 48
  4005e4:	d102c3ff 	sub	sp, sp, #0xb0
  4005e8:	a9027bfd 	stp	x29, x30, [sp, #32]
  4005ec:	910083fd 	add	x29, sp, #0x20
  4005f0:	f9001bf3 	str	x19, [sp, #48]
Line 49
  4005f4:	52800040 	mov	w0, #0x2                   	// #2
  4005f8:	39023fa0 	strb	w0, [x29, #143]
Line 50
  4005fc:	52800060 	mov	w0, #0x3                   	// #3
  400600:	39023ba0 	strb	w0, [x29, #142]

skip_prologue_using_sal () does did not allow for the case where there might
be two SALs with the same line number in a function prologue. Allow this.

Fixes over 50 tests on Aarch64 Ubuntu.

2018-10-24  Alan Hayward  <alan.hayward@arm.com>

	* symtab.c (skip_prologue_using_sal): Don't break for equal line
	numbers.
---
 gdb/symtab.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 2e48d6527e..67ab5d40fa 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -3925,9 +3925,9 @@ skip_prologue_using_sal (struct gdbarch *gdbarch, CORE_ADDR func_addr)
 	  sal = find_pc_line (prologue_sal.end, 0);
 	  if (sal.line == 0)
 	    break;
-	  /* Assume that a consecutive SAL for the same (or larger)
-	     line mark the prologue -> body transition.  */
-	  if (sal.line >= prologue_sal.line)
+	  /* Assume that a SAL to a larger line marks the prologue -> body
+	     transition.  */
+	  if (sal.line > prologue_sal.line)
 	    break;
 	  /* Likewise if we are in a different symtab altogether
 	     (e.g. within a file included via #include).  */
-- 
2.17.1 (Apple Git-112)