[PATCH] Fix -m32 -g -O0 debug info (PR debug/48466)

[Jakub Jelinek]

Hi!

On the pr48466.c testcase below on i?86 -m32 -g -O0 we generate wrong debug
info for some of the variables in main.  This was caused by PR36977 fix,
crtl->stack_realign_tried is true, but fde->drap_reg is INVALID_REGNUM,
but frame_pointer_rtx is being eliminated to hard_frame_pointer_regnum
rather than stack_pointer_regnum.  Fixed by using hfp instead of sp
in that case, the patch is also adding a testcase from PR36977 to make sure
it doesn't regress.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2011-04-06  Jakub Jelinek  <jakub@redhat.com>

	PR debug/48466
	* dwarf2out.c (based_loc_descr): If drap_reg is INVALID_REGNUM, use
	as base_reg whatever register reg has been eliminated to, instead
	of hardcoding STACK_POINTER_REGNUM.

	* gcc.dg/guality/pr36977.c: New test.
	* gcc.dg/guality/pr48466.c: New test.

--- gcc/dwarf2out.c.jj	2011-04-04 08:56:08.000000000 +0200
+++ gcc/dwarf2out.c	2011-04-05 20:51:53.000000000 +0200
@@ -13383,7 +13383,7 @@ based_loc_descr (rtx reg, HOST_WIDE_INT 
 	      int base_reg
 		= DWARF_FRAME_REGNUM ((fde && fde->drap_reg != INVALID_REGNUM)
 				      ? HARD_FRAME_POINTER_REGNUM
-				      : STACK_POINTER_REGNUM);
+				      : REGNO (elim));
 	      return new_reg_loc_descr (base_reg, offset);
 	    }
 
--- gcc/testsuite/gcc.dg/guality/pr36977.c.jj	2011-04-05 20:39:10.000000000 +0200
+++ gcc/testsuite/gcc.dg/guality/pr36977.c	2011-04-05 20:41:27.000000000 +0200
@@ -0,0 +1,32 @@
+/* PR debug/36977 */
+/* { dg-do run } */
+/* { dg-options "-g" } */
+/* { dg-skip-if "" { *-*-* }  { "*" } { "-O0" } } */
+
+void
+foo ()
+{
+}
+
+int
+main ()
+{
+  struct { char c[100]; } cbig;
+  struct { int i[800]; } ibig;
+  struct { long l[900]; } lbig;
+  struct { float f[200]; } fbig;
+  struct { double d[300]; } dbig;
+  struct { short s[400]; } sbig;
+
+  ibig.i[0] = 55;		/* { dg-final { gdb-test 30 "ibig.i\[0\]" "55" } } */
+  ibig.i[100] = 5;		/* { dg-final { gdb-test 30 "ibig.i\[100\]" "5" } } */
+  cbig.c[0] = '\0';		/* { dg-final { gdb-test 30 "cbig.c\[0\]" "'\\0'" } } */
+  cbig.c[99] = 'A';		/* { dg-final { gdb-test 30 "cbig.c\[99\]" "'A'" } } */
+  fbig.f[100] = 11.0;		/* { dg-final { gdb-test 30 "fbig.f\[100\]" "11" } } */
+  dbig.d[202] = 9.0;		/* { dg-final { gdb-test 30 "dbig.d\[202\]" "9" } } */
+  sbig.s[90] = 255;		/* { dg-final { gdb-test 30 "sbig.s\[90\]" "255" } } */
+  lbig.l[333] = 999;		/* { dg-final { gdb-test 30 "lbig.l\[333\]" "999" } } */
+
+  foo ();
+  return 0;
+}
--- gcc/testsuite/gcc.dg/guality/pr48466.c.jj	2011-04-05 20:46:25.000000000 +0200
+++ gcc/testsuite/gcc.dg/guality/pr48466.c	2011-04-05 20:51:29.000000000 +0200
@@ -0,0 +1,41 @@
+/* PR debug/48466 */
+/* { dg-do run } */
+/* { dg-options "-g" } */
+/* { dg-skip-if "" { *-*-* }  { "*" } { "-O0" } } */
+
+struct S { unsigned int a; unsigned int *b; };
+struct T { struct S a; struct S b; };
+struct U { const char *u; };
+int n[10];
+volatile int v;
+
+struct U
+foo (const char *s)
+{
+  struct U r;
+  r.u = s;
+  return r;
+}
+
+void
+bar (struct T *s, int a, int b)
+{
+  s->a.a = a;
+  s->a.b = &s->a.a;
+  s->b.a = b;
+  s->b.b = &s->b.a;
+}
+
+int
+main ()
+{
+  struct T t;
+  struct U x = foo ("this is x");
+  struct S y, z;
+  y.b = n;		/* { dg-final { gdb-test 38 "t.a.a" "17" } } */
+  y.a = 0;		/* { dg-final { gdb-test 38 "*t.a.b" "17" } } */
+  bar (&t, 17, 21);	/* { dg-final { gdb-test 38 "t.b.a" "21" } } */
+  v++;			/* { dg-final { gdb-test 38 "*t.b.b" "21" } } */
+  z = y;
+  return 0;
+}

	Jakub