[Bug other/32163] New: Compiling with stack protector causes reigster spill failure

[Bug other/32163] New: Compiling with stack protector causes reigster spill failure

[uwe at netbsd dot org]

Building NetBSD/sh3 soruce tree with stack protector enabled fails with

/usr/nb-ssp/tools/bin/shle--netbsdelf-gcc -O -Wall -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith -Wno-sign-compare -Wno-traditional
-Wreturn-type -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -Wextra
-Wno-unused-parameter -std=gnu99 -Werror -fstack-protector -Wstack-protector
--param ssp-buffer-size=1 -D_LIBC -DLIBC_SCCS -DSYSLIBC_SCCS -D_REENTRANT
-DHESIOD -DINET6 -DNLS -DYP -I/usr/src/lib/libc/include -I/usr/src/lib/libc
-DSOFTFLOAT -I/usr/src/lib/libc/arch/sh3/softfloat
-I/usr/src/lib/libc/softfloat -DSOFTFLOAT_FOR_GCC -I/usr/src/sys
-I/usr/src/lib/libc/compat/stdlib -I/usr/src/lib/libc/compat/../stdlib
-I/usr/src/lib/libc/../../common/lib/libc/quad
-I/usr/src/lib/libc/../../common/lib/libc/string
-I/usr/src/lib/libc/../../common/lib/libc/arch/sh3/string
-D__DBINTERFACE_PRIVATE -DI18NMODULE_MAJOR=4 -DCITRUS
-I/usr/src/libexec/ld.elf_so -I/usr/src/lib/libc/dlfcn
-I/usr/src/lib/libc/gdtoa -DNO_FENV_H -I/usr/src/lib/libc/arch/sh3/gdtoa
-DCITRUS_ICONV -DWITH_RUNE -I/usr/src/lib/libc -DPOSIX_MISTAKE -DCOMPAT__RES
-DUSE_POLL -DPORTMAP -DWIDE_DOUBLE -DALL_STATE -DUSG_COMPAT -nostdinc -isystem
/usr/nb-ssp/distrib/landisk/usr/include -c -D_I18N_DYNAMIC -fPIC -DPIC
/usr/src/lib/libc/stdio/asprintf.c -o asprintf.so

/usr/src/lib/libc/stdio/asprintf.c: In function '_asprintf':
/usr/src/lib/libc/stdio/asprintf.c:85: error: unable to find a register to
spill in class 'R0_REGS'
/usr/src/lib/libc/stdio/asprintf.c:85: error: this is the insn:
(insn 191 211 210 7 (set (reg/f:SI 2 r2 [246])
        (mem/u/c:SI (plus:SI (reg:SI 12 r12)
                (reg/f:SI 1 r1 [247])) [0 S4 A32])) 171 {movsi_i}
(insn_list:REG_DEP_TRUE 189 (nil))
    (expr_list:REG_DEAD (reg/f:SI 1 r1 [247])
        (expr_list:REG_EQUIV (symbol_ref:SI ("__stack_chk_guard") [flags 0x40]
<var_decl 0xbb93de40 __stack_chk_guard>)
            (nil))))
/usr/src/lib/libc/stdio/asprintf.c:85: confused by earlier errors, bailing out


The compiler is gcc 4.1.2 as imported into the NetBSD tree:

shle--netbsdelf-gcc (GCC) 4.1.2 20070110 (prerelease) (NetBSD nb1 20070110)


-- 
           Summary: Compiling with stack protector causes reigster spill
                    failure
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: uwe at netbsd dot org
 GCC build triplet: i386--netbsdelf
  GCC host triplet: i386--netbsdelf
GCC target triplet: sh3--netbsdelf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug other/32163] Compiling with stack protector causes reigster spill failure

[uwe at netbsd dot org]

------- Comment #1 from uwe at netbsd dot org  2007-05-31 11:37 -------
Created an attachment (id=13638)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13638&action=view)
Preprocessed source of the file that causes the error.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug other/32163] Compiling with stack protector causes reigster spill failure

[uwe at netbsd dot org]

------- Comment #2 from uwe at netbsd dot org  2007-05-31 11:44 -------
Before failing to compile pic version of asprintf.o as reportde above,
non-pic version is successfully compiled.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #3 from kkojima at gcc dot gnu dot org  2007-05-31 13:30 -------
I've confirmed that this fails with 4.1.2, 4.2.0 and 4.3.0
on sh4-unknown-linux-gnu.  A reduced testcase is:

--
int foo ()
{
  char *p;
  char fext[128];

  p = fext;
  bar (&p, (void *)0);
  if (p)
    free (p);
  return 0;
}
--
which fails with -O -fpic -fstack-protector.  Curiously the error
went away with -O2 -fpic -fstack-protector.


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kkojima at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
          Component|other                       |target
     Ever Confirmed|0                           |1
           Keywords|                            |ice-on-valid-code
      Known to fail|                            |4.1.2 4.2.0 4.3.0
   Last reconfirmed|0000-00-00 00:00:00         |2007-05-31 13:30:12
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #4 from kkojima at gcc dot gnu dot org  2007-06-01 00:17 -------
In the faulty case, stack protector inserts PIC codes after the result
is set to R0 register.  It looks like

  rX = __stack_chk_guard@GOT
  A = rX + r12
  B = mem[A]

and combine optimization pass makes this turn into

  rX = __stack_chk_guard@GOT
  B = mem[rX + r12]

Unfortunately, the last insn requires R0 which is already used and we
see the famous R0 spill failure.  We didn't get this error on SH4 with
-O2 because the first insn scheduling and other optimizations move
the insn which set the result to R0 after these protector codes.
But it looks to be fragile even on SH4 -O2.  I'm testing the patch
below on the trunk.

        * config/sh/sh.md (symGOT_load): Don't schedule insns when
        the symbol is generated with the stack protector.

--- ORIG/trunk/gcc/config/sh/sh.md      2007-04-27 21:30:47.000000000 +0900
+++ LOCAL/trunk/gcc/config/sh/sh.md     2007-06-01 08:21:18.000000000 +0900
@@ -8502,6 +8502,20 @@ label:
                                             operands[2],
                                             gen_rtx_REG (Pmode, PIC_REG)));

+  /* When stack protector inserts codes after the result is set to
+     R0, @(rX, r12) will cause a spill failure for R0.  Don't schedule
+     insns to avoid combining (set A (plus rX r12)) and (set op0 (mem A))
+     when rX is a GOT address for the guard symbol.  Ugly but doesn't
+     matter because this is a rare situation.  */
+  if (!TARGET_SHMEDIA
+      && flag_stack_protect
+      && GET_CODE (operands[1]) == CONST
+      && GET_CODE (XEXP (operands[1], 0)) == UNSPEC
+      && GET_CODE (XVECEXP (XEXP (operands[1], 0), 0, 0)) == SYMBOL_REF
+      && strcmp (XSTR (XVECEXP (XEXP (operands[1], 0), 0, 0), 0),
+                \"__stack_chk_guard\") == 0)
+    emit_insn (gen_blockage ());
+
   /* N.B. This is not constant for a GOTPLT relocation.  */
   mem = gen_rtx_MEM (Pmode, operands[3]);
   MEM_NOTRAP_P (mem) = 1;


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #5 from kkojima at gcc dot gnu dot org  2007-06-03 04:39 -------
Subject: Bug 32163

Author: kkojima
Date: Sun Jun  3 04:38:52 2007
New Revision: 125292

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=125292
Log:
        PR target/32163
        * config/sh/sh.md (symGOT_load): Don't schedule insns when
        the symbol is generated with the stack protector.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/sh/sh.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #6 from kkojima at gcc dot gnu dot org  2007-06-08 05:54 -------
Subject: Bug 32163

Author: kkojima
Date: Fri Jun  8 05:53:57 2007
New Revision: 125558

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=125558
Log:
        PR target/32163
        Backport from mainline.
        * config/sh/sh.md (symGOT_load): Don't schedule insns when
        the symbol is generated with the stack protector.


Modified:
    branches/gcc-4_2-branch/gcc/ChangeLog
    branches/gcc-4_2-branch/gcc/config/sh/sh.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #7 from kkojima at gcc dot gnu dot org  2007-06-08 05:56 -------
Subject: Bug 32163

Author: kkojima
Date: Fri Jun  8 05:56:28 2007
New Revision: 125559

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=125559
Log:
        PR target/32163
        Backport from mainline.
        * config/sh/sh.md (symGOT_load): Don't schedule insns when
        the symbol is generated with the stack protector.


Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/config/sh/sh.md


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163

[Bug target/32163] Compiling with stack protector causes reigster spill failure

[kkojima at gcc dot gnu dot org]

------- Comment #8 from kkojima at gcc dot gnu dot org  2007-06-08 05:58 -------
Fixed.


-- 

kkojima at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32163