[Bug c/65066] New: [5 Regression] ICE: Segmentation fault with -Wformat=2

[Bug c/65066] New: [5 Regression] ICE: Segmentation fault with -Wformat=2

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65066

            Bug ID: 65066
           Summary: [5 Regression] ICE: Segmentation fault with -Wformat=2
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: trippels at gcc dot gnu.org
                CC: mpolacek at gcc dot gnu.org

markus@x4 /tmp % cat rt_names.i
extern int sscanf(__const char *__restrict __s,
                  __const char *__restrict __format, ...);
int *a;
void foo() { sscanf(0, "0x%x  #", a); }

markus@x4 /tmp % gcc -Wformat=2 -c rt_names.i
rt_names.i: In function ‘foo’:
rt_names.i:4:1: internal compiler error: Segmentation fault
 void foo() { sscanf(0, "0x%x  #", a); }
 ^
0xaed31f crash_signal
        ../../gcc/gcc/toplev.c:383
0x57c131 check_format_types
        ../../gcc/gcc/c-family/c-format.c:2495
0x57c131 check_format_info_main
        ../../gcc/gcc/c-family/c-format.c:2326
0x6a6ec8 check_format_arg
        ../../gcc/gcc/c-family/c-format.c:1623
0x6a7604 check_format_info
        ../../gcc/gcc/c-family/c-format.c:1358
0x6a7604 check_function_format(tree_node*, int, tree_node**)
        ../../gcc/gcc/c-family/c-format.c:1028
0x6949a7 check_function_arguments(tree_node const*, int, tree_node**)
        ../../gcc/gcc/c-family/c-common.c:9540
0x6293dd build_function_call_vec(unsigned int, vec<unsigned int, va_heap,
vl_ptr>, tree_node*, vec<tree_node*, va_gc, vl_embed>*, vec<tree_node*, va_gc,
vl_embed>*)
        ../../gcc/gcc/c/c-typeck.c:2994
0x64b44a c_parser_postfix_expression_after_primary
        ../../gcc/gcc/c/c-parser.c:7894
0x644a36 c_parser_postfix_expression
        ../../gcc/gcc/c/c-parser.c:7715
0x6470fa c_parser_unary_expression
        ../../gcc/gcc/c/c-parser.c:6602
0x647d0f c_parser_cast_expression
        ../../gcc/gcc/c/c-parser.c:6440
0x647ef2 c_parser_binary_expression
        ../../gcc/gcc/c/c-parser.c:6255
0x648a55 c_parser_conditional_expression
        ../../gcc/gcc/c/c-parser.c:6031
0x649030 c_parser_expr_no_commas
        ../../gcc/gcc/c/c-parser.c:5949
0x649702 c_parser_expression
        ../../gcc/gcc/c/c-parser.c:8022
0x64a129 c_parser_expression_conv
        ../../gcc/gcc/c/c-parser.c:8055
0x642988 c_parser_statement_after_labels
        ../../gcc/gcc/c/c-parser.c:5115
0x644183 c_parser_compound_statement_nostart
        ../../gcc/gcc/c/c-parser.c:4701
0x65605e c_parser_compound_statement
        ../../gcc/gcc/c/c-parser.c:4538
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

Probably started with r220677.
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From: "terry.guo at arm dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/65067] New: regression on accessing volatile bit field
Date: Sun, 15 Feb 2015 08:59:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide067

            Bug ID: 65067
           Summary: regression on accessing volatile bit field
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: terry.guo at arm dot com

Due to the impact of option -fstrict-volatile-bitfields, current trunk gcc
generate worse code to access volatile bitfield which can be nicely handled
with gcc 4.8.

Here is test case:
$ cat y.c
#include <stdint.h>

struct tmp {
 uint32_t dummy;
 union {
  struct {
   uint32_t xyz : 1;
   uint32_t mode: 3;
   uint32_t res : 28;
  } bf;
  uint32_t wordval;
 } reg;
};

void set_mode(int mode)
{
 volatile struct tmp *t = (struct tmp *) 0x1000;
 t->reg.bf.mode = mode;
}

When compiled with gcc 4.8 and command
"gcc-arm-none-eabi-4_8-2014q3/bin/arm-none-eabi-gcc -mthumb -mcpu=cortex-m3 -O2
-S y.c", the generated code is good and expected:

    mov    r3, #4096
    ldr    r2, [r3, #4]
    bfi    r2, r0, #1, #3
    str    r2, [r3, #4]
    bx    lr

But when compiled with current gcc 5.0 and same command, worse code is
generated:

        mov     r2, #4096
        ldr     r3, [r2, #4]
        and     r0, r0, #7
        bic     r3, r3, #14
        orr     r3, r3, r0, lsl #1
        str     r3, [r2, #4]
        bx      lr

If turn off the option -fstrict-volatile-bitfields, we can get expected code.

In my opinion, this gcc code is making bad decision:

  /* Handle -fstrict-volatile-bitfields in the cases where it applies.  */
  if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, fieldmode,
                                  bitregion_start, bitregion_end))
    {

The function strict_volatile_bitfield_p should make correct decision that we
don't need to consider strict volatile bitfield here for this case. When debug
this function, the arguments are:

Breakpoint 1, strict_volatile_bitfield_p (op0=0x7ffff6096e88, bitsize=3,
bitnum3, fieldmode=SImode, bitregion_start2, bitregion_endc)

The mode of op0 is also SImode. So it should be easy to figure out that we are
working on a perfect 32-bit entity and no boundary crossing here.

[Bug c/65066] [5 Regression] ICE: Segmentation fault with -Wformat=2

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65066

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2015-02-15
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org
   Target Milestone|---                         |5.0
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Ouch.

[Bug c/65066] [5 Regression] ICE: Segmentation fault with -Wformat=2

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65066

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug c/65066] [5 Regression] ICE: Segmentation fault with -Wformat=2

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65066

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Mon Feb 16 11:16:33 2015
New Revision: 220732

URL: https://gcc.gnu.org/viewcvs?rev=220732&root=gcc&view=rev
Log:
    PR c/65066
    * c-format.c (check_format_types): Handle null param.

    * gcc.dg/pr65066.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr65066.c
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-format.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/65066] [5 Regression] ICE: Segmentation fault with -Wformat=2

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65066

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.