optimization/8916: unsigned char assign gets hosed.

optimization/8916: unsigned char assign gets hosed.

[jcphillips]

>Number:         8916
>Category:       optimization
>Synopsis:       unsigned char assign gets hosed.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Dec 12 08:56:02 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     jcphillips@yahoo.com
>Release:        gcc v3.2
>Organization:
>Environment:
cygwin.  gcc built for mcore-elf.
>Description:
The following source fails to generate correct asm:
----------------
extern void ExtFunc(char *c);

void test()
  {
  unsigned char data = 166;
  ExtFunc(&data);
  }
--------------------------
mcore-elf-objdump output is:
--------------------------
test.o:     file format elf32-mcore-big

Disassembly of section .text:

00000000 <test>:
   0:   24f0            subi    r0, 16
   2:   9f20            st      r15, (r0, 8)
   4:   2c07            bmaski  r7, 0
   6:   b700            stb     r7, (r0, 0)
   8:   1202            mov     r2, r0
   a:   7f02            jsri    0x0     // from address pool at 0x14
   c:   8f20            ld      r15, (r0, 8)
   e:   20f0            addi    r0, 16
  10:   00cf            jmp     r15
  12:   0000            bkpt
  14:   0000            bkpt
        ...
--------------------------
The bmaski r7,0 causes the char value to be 0xFF.
When compiled without optimization, result is fine.
>How-To-Repeat:
compile with:
 mcore-elf-gcc -c -O2 -mbig-endian -m210 test.c
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: