https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54089
--- Comment #50 from Alexander Klepikov <klepikov.alex+bugs at gmail dot com>
---
> > I've found that my patch catches integer division. In short, it appears to
> > work unpredictable. It looks like there's no easy way to catch right shift.
>
> What do you mean it catches integer division? There could be several places
> during compilation, where the compiler will try to convert integer division
> to right shifts. But it will not do so unless it's wrong. The patterns you
> have added shouldn't match a division operation.
Ooh, my bad! You are absolutely right. A function is inlined and division is
converted to 4 'shar's which at combine pass are catched by 'define_insn
"ashrsi3_libcall_collapsed"' which is little unexpected to me. Of course, it is
expanded at 'split' pass to lib call. 5 and less right shifts should not
convert to a lib call, but that can be easily corrected.
But maybe there is a way to exclude particular insn from combine pass? (I guess
not).
Here are the files that confused me:
$ cat pr49880-3.c
/* Check that the option -mdiv=call-table works. */
/* { dg-do link } */
/* { dg-options "-mdiv=call-table" } */
int
test00 (int a, int b)
{
return a / b;
}
unsigned int
test01 (unsigned int a, unsigned b)
{
return a / b;
}
int
main (int argc, char** argv)
{
return test00 (argc, 123) + test01 (argc, 123);
}
Not-patched GCC
$ cat pr49880-3.s.clean
.file "pr49880-3.c"
.text
.text
.align 1
.align 2
.global _test00
.type _test00, @function
_test00:
mov.l .L4,r0
sts.l pr,@-r15
jsr @r0
nop
lds.l @r15+,pr
rts
nop
.L5:
.align 2
.L4:
.long ___sdivsi3
.size _test00, .-_test00
.align 1
.align 2
.global _test01
.type _test01, @function
_test01:
mov.l .L8,r0
sts.l pr,@-r15
jsr @r0
nop
lds.l @r15+,pr
rts
nop
.L9:
.align 2
.L8:
.long ___udivsi3
.size _test01, .-_test01
.section .text.startup,"ax",@progbits
.align 1
.align 2
.global _main
.type _main, @function
_main:
mov.l .L11,r1
dmuls.l r1,r4
sts mach,r0
shar r0
shar r0
shar r0
shar r0
mov r4,r1
shll r1
subc r1,r1
sub r1,r0
mov.l .L12,r1
dmulu.l r1,r4
sts mach,r1
sub r1,r4
shlr r4
add r4,r1
shlr2 r1
shlr2 r1
shlr2 r1
rts
add r1,r0
.L13:
.align 2
.L11:
.long 558694933
.L12:
.long 174592167
.size _main, .-_main
.ident "GCC: (GNU) 13.1.0"
Patched GCC
$ cat pr49880-3.s
.file "pr49880-3.c"
.text
.text
.align 1
.align 2
.global _test00
.type _test00, @function
_test00:
mov.l .L4,r0
sts.l pr,@-r15
jsr @r0
nop
lds.l @r15+,pr
rts
nop
.L5:
.align 2
.L4:
.long ___sdivsi3
.size _test00, .-_test00
.align 1
.align 2
.global _test01
.type _test01, @function
_test01:
mov.l .L8,r0
sts.l pr,@-r15
jsr @r0
nop
lds.l @r15+,pr
rts
nop
.L9:
.align 2
.L8:
.long ___udivsi3
.size _test01, .-_test01
.section .text.startup,"ax",@progbits
.align 1
.align 2
.global _main
.type _main, @function
_main:
mov.l .L12,r2
mov r4,r1
sts.l pr,@-r15
dmuls.l r2,r4
mov.l .L13,r2
jsr @r2
sts mach,r4
mov r1,r2
shll r2
subc r2,r2
mov r4,r0
sub r2,r0
mov.l .L14,r2
dmulu.l r2,r1
sts mach,r2
sub r2,r1
shlr r1
add r1,r2
shlr2 r2
shlr2 r2
shlr2 r2
add r2,r0
lds.l @r15+,pr
rts
nop
.L15:
.align 2
.L12:
.long 558694933
.L13:
.long ___ashiftrt_r4_4
.L14:
.long 174592167
.size _main, .-_main
.ident "GCC: (GNU) 13.1.0"
Now concerning GCC testsuite. I ran it in such way:
make check RUNTESTFLAGS="CFLAGS='$CFLAGS -I/usr/local/sh-elf/include/'
--target_board=sh-sim\{-m2e,-m4\}\{-ml,-mb\}"
There are lots of failed tests on non-patched GCC. Even if I narrow tests list
to sh.exp, it still fails a lot of times. At last there's nothing in logs that
produce ICE in RTL. I'm not sure I could find a crash due to the patch at all,
even if it were there.
And finally, 'parallel' appears to be unnecessary, thank you for pointing.
