[Bug c/65716] New: Integral promotion wrong with arm version

[juan-antonio.gar...@nabla-designs.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65716

            Bug ID: 65716
           Summary: Integral promotion wrong with arm version
           Product: gcc
           Version: 4.6.3
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: juan-antonio.gar...@nabla-designs.com

Created attachment 35277
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35277&action=edit
Compiler output to gcc -v -save-temps

test.c:

int main()
{
  char a =-1;
  int b = a;

  while(b>0);

  return 0;
}

This program has different behaviour in i386 and arm architectures.

i386 : The program exits normally.

arm  : The program loops for ever because evaluates b > 0.

******************************************************************
test.i:

# 1 "test.c"
# 1 "<interno>"
# 1 "<línea-de-orden>"
# 1 "test.c"
int main()
{
  char a =-1;
  int b = a;

  while(b>0);

  return 0;
}

********************************************************************

test.s:

    .syntax unified
    .arch armv7-a
    .eabi_attribute 27, 3
    .fpu vfpv3-d16
    .eabi_attribute 20, 1
    .eabi_attribute 21, 1
    .eabi_attribute 23, 3
    .eabi_attribute 24, 1
    .eabi_attribute 25, 1
    .eabi_attribute 26, 2
    .eabi_attribute 30, 6
    .eabi_attribute 34, 1
    .eabi_attribute 18, 4
    .thumb
    .file    "test.c"
    .text
    .align    2
    .global    main
    .thumb
    .thumb_func
    .type    main, %function
main:
    @ args = 0, pretend = 0, frame = 8
    @ frame_needed = 1, uses_anonymous_args = 0
    @ link register save eliminated.
    push    {r7}
    sub    sp, sp, #12
    add    r7, sp, #0
    mov    r3, #255
    strb    r3, [r7, #7]
    ldrb    r3, [r7, #7]    @ zero_extendqisi2
    str    r3, [r7, #0]
.L2:
    ldr    r3, [r7, #0]
    cmp    r3, #0
    bgt    .L2
    mov    r3, #0
    mov    r0, r3
    add    r7, r7, #12
    mov    sp, r7
    pop    {r7}
    bx    lr
    .size    main, .-main
    .ident    "GCC: (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3"
    .section    .note.GNU-stack,"",%progbits