[PATCH] Fix up ppc64-linux profiledbootstrap - .toc section references in .debug_loc (PR target/51957)

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

profiledbootstrap currently fails on powerpc64-linux (64-bit).  The problem
is that the linker errors on .toc section references from within
non-allocated sections.  Alan changed the linker some months ago to
not die with assertion failure, but error out on these, and the attached
testcase reduced from cp/parser.c during bootstrap shows that we still
can hit it in some cases.  The problem here is that var-tracking.c
(adjust_insn) isn't able to delegitimize it, because the UNSPEC_TOCREL
isn't added there to r2 register, but to a debug_expr (which only afterwards
is found to contain r2 value).  So the UNSPEC_TOCREL makes it through to
mem_loc_descriptor, where it is already properly delegitimized into a
(mem (symbol_ref (".LC0")) where .LC0 is a constant pool (.toc) symbol.
We in some places try to prefer avoid_constant_pool_reference values over
the mems, in this case avoid_constant_pool returns (symbol_ref "w"), which
is a non-local symbol which isn't const_ok_for_output though.  So
mem_loc_descriptor on the avoid_constant_pool_reference value fails and we
try the original (mem (symbol_ref (".LC0")) - on other targets this is still
useful, if we know the right value is in say some .got entry etc. and we
can reference that location from within the .debug_info, we win.
Unfortunately the ppc64 linker doesn't like this, so we need to reject
those.  The following patch adds a target hook and rejects there from
emitting into .debug_info/.debug_loc any SYMBOL_REFs that are in the
.toc section.

Bootstrapped/regtested on x86_64-linux and i686-linux, profiledbootstrapped
on powerpc64-linux (both --with-cpu=default32 and defaulting to 64-bit,
the last one failed without this patch), powerpc64-linux regtest is in
progress (but the testcase in the patch has been tested already to
fail without the patch and succeed with the patch).
Ok for trunk?

2012-01-23  Jakub Jelinek  <jakub@redhat.com>

	PR target/51957
	* target.def (const_not_ok_for_debug_p): New hook.
	* doc/tm.texi.in (TARGET_CONST_NOT_OK_FOR_DEBUG_P): New hook
	documentation.
	* doc/tm.texi: Regenerated.
	* dwarf2out.c (const_ok_for_output_1): If
	targetm.const_not_ok_for_debug_p returns true, fail.
	* config/rs6000/rs6000.c (rs6000_const_not_ok_for_debug_p): New
	function.
	(TARGET_CONST_NOT_OK_FOR_DEBUG_P): Redefine.

	* gcc.dg/pr51957-1.c: New test.
	* gcc.dg/pr51957-1.h: New file.
	* gcc.dg/pr51957-2.c: New test.

--- gcc/target.def.jj	2012-01-20 12:35:16.000000000 +0100
+++ gcc/target.def	2012-01-23 13:14:52.601638343 +0100
@@ -1382,6 +1382,14 @@ DEFHOOK
  rtx, (rtx x),
  delegitimize_mem_from_attrs)
 
+/* Given an RTX, return true if it is not ok to emit it into debug info
+   section.  */
+DEFHOOK
+(const_not_ok_for_debug_p,
+ "",
+ bool, (rtx x),
+ hook_bool_rtx_false)
+
 /* Given an address RTX, say whether it is valid.  */
 DEFHOOK
 (legitimate_address_p,
--- gcc/doc/tm.texi.in.jj	2012-01-20 12:35:10.000000000 +0100
+++ gcc/doc/tm.texi.in	2012-01-23 13:27:19.544241676 +0100
@@ -5567,6 +5567,11 @@ the semantics of these opaque @code{UNSP
 into their original form.
 @end deftypefn
 
+@hook TARGET_CONST_NOT_OK_FOR_DEBUG_P
+This hook should return true if @var{x} should not be emitted into
+debug sections.
+@end deftypefn
+
 @hook TARGET_CANNOT_FORCE_CONST_MEM
 This hook should return true if @var{x} is of a form that cannot (or
 should not) be spilled to the constant pool.  @var{mode} is the mode
--- gcc/doc/tm.texi.jj	2012-01-20 12:35:10.000000000 +0100
+++ gcc/doc/tm.texi	2012-01-23 13:27:33.000000000 +0100
@@ -5631,6 +5631,11 @@ the semantics of these opaque @code{UNSP
 into their original form.
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_CONST_NOT_OK_FOR_DEBUG_P (rtx @var{x})
+This hook should return true if @var{x} should not be emitted into
+debug sections.
+@end deftypefn
+
 @deftypefn {Target Hook} bool TARGET_CANNOT_FORCE_CONST_MEM (enum machine_mode @var{mode}, rtx @var{x})
 This hook should return true if @var{x} is of a form that cannot (or
 should not) be spilled to the constant pool.  @var{mode} is the mode
--- gcc/dwarf2out.c.jj	2012-01-22 16:02:10.000000000 +0100
+++ gcc/dwarf2out.c	2012-01-23 13:58:09.887380014 +0100
@@ -10683,6 +10683,13 @@ const_ok_for_output_1 (rtx *rtlp, void *
       return 1;
     }
 
+  if (targetm.const_not_ok_for_debug_p (rtl))
+    {
+      expansion_failed (NULL_TREE, rtl,
+			"Expression rejected for debug by the backend.\n");
+      return 1;
+    }
+
   if (GET_CODE (rtl) != SYMBOL_REF)
     return 0;
 
--- gcc/config/rs6000/rs6000.c.jj	2012-01-22 16:02:10.000000000 +0100
+++ gcc/config/rs6000/rs6000.c	2012-01-23 13:25:05.092031129 +0100
@@ -1106,6 +1106,7 @@ static rtx rs6000_debug_legitimize_addre
 static rtx rs6000_legitimize_tls_address (rtx, enum tls_model);
 static void rs6000_output_dwarf_dtprel (FILE *, int, rtx) ATTRIBUTE_UNUSED;
 static rtx rs6000_delegitimize_address (rtx);
+static bool rs6000_const_not_ok_for_debug_p (rtx);
 static rtx rs6000_tls_get_addr (void);
 static rtx rs6000_got_sym (void);
 static int rs6000_tls_symbol_ref_1 (rtx *, void *);
@@ -1405,6 +1406,9 @@ static const struct attribute_spec rs600
 #undef TARGET_DELEGITIMIZE_ADDRESS
 #define TARGET_DELEGITIMIZE_ADDRESS rs6000_delegitimize_address
 
+#undef TARGET_CONST_NOT_OK_FOR_DEBUG_P
+#define TARGET_CONST_NOT_OK_FOR_DEBUG_P rs6000_const_not_ok_for_debug_p
+
 #undef TARGET_ASM_FUNCTION_PROLOGUE
 #define TARGET_ASM_FUNCTION_PROLOGUE rs6000_output_function_prologue
 #undef TARGET_ASM_FUNCTION_EPILOGUE
@@ -5815,6 +5819,25 @@ rs6000_delegitimize_address (rtx orig_x)
   return orig_x;
 }
 
+/* Return true if X shouldn't be emitted into the debug info.
+   The linker doesn't like .toc section references from
+   .debug_* sections, so reject .toc section symbols.  */
+
+static bool
+rs6000_const_not_ok_for_debug_p (rtx x)
+{
+  if (GET_CODE (x) == SYMBOL_REF
+      && CONSTANT_POOL_ADDRESS_P (x))
+    {
+      rtx c = get_pool_constant (x);
+      enum machine_mode cmode = get_pool_mode (x);
+      if (ASM_OUTPUT_SPECIAL_POOL_ENTRY_P (c, cmode))
+	return true;
+    }
+
+  return false;
+}
+
 /* Construct the SYMBOL_REF for the tls_get_addr function.  */
 
 static GTY(()) rtx rs6000_tls_symbol;
--- gcc/testsuite/gcc.dg/pr51957-1.c.jj	2012-01-23 14:06:45.024357678 +0100
+++ gcc/testsuite/gcc.dg/pr51957-1.c	2012-01-23 14:12:02.895492825 +0100
@@ -0,0 +1,29 @@
+/* PR target/51957 */
+/* { dg-do link } */
+/* { dg-options "-O2 -g -fprofile-use" } */
+/* { dg-additional-sources "pr51957-2.c" } */
+
+int v[128];
+#include "pr51957-1.h"
+
+void
+foo (U *x)
+{
+  T *a = x->u;
+  while (1)
+    {
+      union R *b;
+      b = fn1 ();
+      if (b != w[0] && !(v[b->p->c] == 1))
+	{
+	  fn2 (a->t, "foobar", b->p);
+	  b = w[0];
+	}
+      if (b != w[0])
+	fn3 ();
+      if (w[0] && b != w[0])
+	fn4 (b->p);
+      if (b != w[0] && (v[b->p->c] == 1) && fn4 (b->p))
+	break;
+    }
+}
--- gcc/testsuite/gcc.dg/pr51957-1.h.jj	2012-01-23 14:06:56.491290757 +0100
+++ gcc/testsuite/gcc.dg/pr51957-1.h	2012-01-23 14:07:35.243060438 +0100
@@ -0,0 +1,9 @@
+union R { int c; union R *p; };
+extern union R *w[];
+typedef struct { int t; } T;
+typedef struct { void *u; } U;
+union R *fn1 (void);
+void fn2 (int, const char *, union R *);
+void fn3 (void);
+int fn4 (union R *);
+void foo (U *x);
--- gcc/testsuite/gcc.dg/pr51957-2.c.jj	2012-01-23 14:10:59.840862700 +0100
+++ gcc/testsuite/gcc.dg/pr51957-2.c	2012-01-23 14:10:52.870904033 +0100
@@ -0,0 +1,35 @@
+/* PR target/51957 */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+#include "pr51957-1.h"
+
+union R *w[10];
+
+union R *
+fn1 (void)
+{
+  return (union R *) 0;
+}
+
+void
+fn2 (int x, const char *y, union R *z)
+{
+}
+
+void
+fn3 (void)
+{
+}
+
+int
+fn4 (union R *x)
+{
+  return 0;
+}
+
+int
+main ()
+{
+  return 0;
+}

	Jakub