https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49263
--- Comment #37 from Alexander Klepikov <klepikov.alex+bugs at gmail dot com>
---
> Can you also compile for little endian, and most of all, use -O2
> optimization level. Some optimizations are not done below -O2.
Here's source file, I added functions with non-constant shifts
$ cat f.c
#define ADDR 0xFFFF0000
#define P ((unsigned char *)ADDR)
#define FLAG 0x40
#define S 7
unsigned char f_char_var(char v){
return (v & FLAG) == FLAG;
}
unsigned char f_unsigned_char_var(unsigned char v){
return (v & FLAG) == FLAG;
}
unsigned char f_symbol(void){
return (*P & FLAG) == FLAG;
}
unsigned char f_symbol_zero(void){
return (*P & FLAG) == 0;
}
unsigned char f_symbol_non_zero(void){
return (*P & FLAG) != 0;
}
unsigned int dyn_lshift (unsigned int x, unsigned int y)
{
return x << (y & 31);
}
unsigned int dyn_rshift (unsigned int x, unsigned int y)
{
return x >> (y & 31);
}
unsigned int really_dyn_lshift (unsigned int x, unsigned int y)
{
return x << y;
}
unsigned int really_dyn_rshift (unsigned int x, unsigned int y)
{
return x >> y;
}
With patch disabled, -O2 -mb:
$ cat f.s
.file "f.c"
.text
.text
.align 1
.align 2
.global _f_char_var
.type _f_char_var, @function
_f_char_var:
mov.l .L4,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L5:
.align 2
.L4:
.long ___ashiftrt_r4_6
.size _f_char_var, .-_f_char_var
.align 1
.align 2
.global _f_unsigned_char_var
.type _f_unsigned_char_var, @function
_f_unsigned_char_var:
mov.l .L8,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L9:
.align 2
.L8:
.long ___ashiftrt_r4_6
.size _f_unsigned_char_var, .-_f_unsigned_char_var
.align 1
.align 2
.global _f_symbol
.type _f_symbol, @function
_f_symbol:
mov.l .L12,r1
sts.l pr,@-r15
mov.b @r1,r4
mov.l .L13,r1
jsr @r1
nop
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L14:
.align 2
.L12:
.long -65536
.L13:
.long ___ashiftrt_r4_6
.size _f_symbol, .-_f_symbol
.align 1
.align 2
.global _f_symbol_zero
.type _f_symbol_zero, @function
_f_symbol_zero:
mov.l .L16,r1
mov.b @r1,r0
tst #64,r0
rts
movt r0
.L17:
.align 2
.L16:
.long -65536
.size _f_symbol_zero, .-_f_symbol_zero
.align 1
.align 2
.global _f_symbol_non_zero
.type _f_symbol_non_zero, @function
_f_symbol_non_zero:
mov.l .L20,r1
sts.l pr,@-r15
mov.b @r1,r4
mov.l .L21,r1
jsr @r1
nop
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L22:
.align 2
.L20:
.long -65536
.L21:
.long ___ashiftrt_r4_6
.size _f_symbol_non_zero, .-_f_symbol_non_zero
.align 1
.align 2
.global _dyn_lshift
.type _dyn_lshift, @function
_dyn_lshift:
mov.l .L25,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L26:
.align 2
.L25:
.long ___ashlsi3_r0
.size _dyn_lshift, .-_dyn_lshift
.align 1
.align 2
.global _dyn_rshift
.type _dyn_rshift, @function
_dyn_rshift:
mov.l .L29,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L30:
.align 2
.L29:
.long ___lshrsi3_r0
.size _dyn_rshift, .-_dyn_rshift
.align 1
.align 2
.global _really_dyn_lshift
.type _really_dyn_lshift, @function
_really_dyn_lshift:
mov.l .L33,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L34:
.align 2
.L33:
.long ___ashlsi3_r0
.size _really_dyn_lshift, .-_really_dyn_lshift
.align 1
.align 2
.global _really_dyn_rshift
.type _really_dyn_rshift, @function
_really_dyn_rshift:
mov.l .L37,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L38:
.align 2
.L37:
.long ___lshrsi3_r0
.size _really_dyn_rshift, .-_really_dyn_rshift
.ident "GCC: (GNU) 12.3.0"
With patch disabled, -O2 -ml
$ cat f.s
.file "f.c"
.text
.little
.text
.align 1
.align 2
.global _f_char_var
.type _f_char_var, @function
_f_char_var:
mov.l .L4,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L5:
.align 2
.L4:
.long ___ashiftrt_r4_6
.size _f_char_var, .-_f_char_var
.align 1
.align 2
.global _f_unsigned_char_var
.type _f_unsigned_char_var, @function
_f_unsigned_char_var:
mov.l .L8,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L9:
.align 2
.L8:
.long ___ashiftrt_r4_6
.size _f_unsigned_char_var, .-_f_unsigned_char_var
.align 1
.align 2
.global _f_symbol
.type _f_symbol, @function
_f_symbol:
mov.l .L12,r1
sts.l pr,@-r15
mov.b @r1,r4
mov.l .L13,r1
jsr @r1
nop
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L14:
.align 2
.L12:
.long -65536
.L13:
.long ___ashiftrt_r4_6
.size _f_symbol, .-_f_symbol
.align 1
.align 2
.global _f_symbol_zero
.type _f_symbol_zero, @function
_f_symbol_zero:
mov.l .L16,r1
mov.b @r1,r0
tst #64,r0
rts
movt r0
.L17:
.align 2
.L16:
.long -65536
.size _f_symbol_zero, .-_f_symbol_zero
.align 1
.align 2
.global _f_symbol_non_zero
.type _f_symbol_non_zero, @function
_f_symbol_non_zero:
mov.l .L20,r1
sts.l pr,@-r15
mov.b @r1,r4
mov.l .L21,r1
jsr @r1
nop
mov r4,r0
and #1,r0
lds.l @r15+,pr
rts
nop
.L22:
.align 2
.L20:
.long -65536
.L21:
.long ___ashiftrt_r4_6
.size _f_symbol_non_zero, .-_f_symbol_non_zero
.align 1
.align 2
.global _dyn_lshift
.type _dyn_lshift, @function
_dyn_lshift:
mov.l .L25,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L26:
.align 2
.L25:
.long ___ashlsi3_r0
.size _dyn_lshift, .-_dyn_lshift
.align 1
.align 2
.global _dyn_rshift
.type _dyn_rshift, @function
_dyn_rshift:
mov.l .L29,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L30:
.align 2
.L29:
.long ___lshrsi3_r0
.size _dyn_rshift, .-_dyn_rshift
.align 1
.align 2
.global _really_dyn_lshift
.type _really_dyn_lshift, @function
_really_dyn_lshift:
mov.l .L33,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L34:
.align 2
.L33:
.long ___ashlsi3_r0
.size _really_dyn_lshift, .-_really_dyn_lshift
.align 1
.align 2
.global _really_dyn_rshift
.type _really_dyn_rshift, @function
_really_dyn_rshift:
mov.l .L37,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L38:
.align 2
.L37:
.long ___lshrsi3_r0
.size _really_dyn_rshift, .-_really_dyn_rshift
.ident "GCC: (GNU) 12.3.0"
With patch enabled -O2 -mb
$ cat f.s
.file "f.c"
.text
.text
.align 1
.align 2
.global _f_char_var
.type _f_char_var, @function
_f_char_var:
mov r4,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.size _f_char_var, .-_f_char_var
.align 1
.align 2
.global _f_unsigned_char_var
.type _f_unsigned_char_var, @function
_f_unsigned_char_var:
mov r4,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.size _f_unsigned_char_var, .-_f_unsigned_char_var
.align 1
.align 2
.global _f_symbol
.type _f_symbol, @function
_f_symbol:
mov.l .L5,r1
mov.b @r1,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.L6:
.align 2
.L5:
.long -65536
.size _f_symbol, .-_f_symbol
.align 1
.align 2
.global _f_symbol_zero
.type _f_symbol_zero, @function
_f_symbol_zero:
mov.l .L8,r1
mov.b @r1,r0
tst #64,r0
rts
movt r0
.L9:
.align 2
.L8:
.long -65536
.size _f_symbol_zero, .-_f_symbol_zero
.align 1
.align 2
.global _f_symbol_non_zero
.type _f_symbol_non_zero, @function
_f_symbol_non_zero:
mov.l .L11,r1
mov.b @r1,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.L12:
.align 2
.L11:
.long -65536
.size _f_symbol_non_zero, .-_f_symbol_non_zero
.align 1
.align 2
.global _dyn_lshift
.type _dyn_lshift, @function
_dyn_lshift:
mov.l .L15,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L16:
.align 2
.L15:
.long ___ashlsi3_r0
.size _dyn_lshift, .-_dyn_lshift
.align 1
.align 2
.global _dyn_rshift
.type _dyn_rshift, @function
_dyn_rshift:
mov.l .L19,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L20:
.align 2
.L19:
.long ___lshrsi3_r0
.size _dyn_rshift, .-_dyn_rshift
.align 1
.align 2
.global _really_dyn_lshift
.type _really_dyn_lshift, @function
_really_dyn_lshift:
mov.l .L23,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L24:
.align 2
.L23:
.long ___ashlsi3_r0
.size _really_dyn_lshift, .-_really_dyn_lshift
.align 1
.align 2
.global _really_dyn_rshift
.type _really_dyn_rshift, @function
_really_dyn_rshift:
mov.l .L27,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L28:
.align 2
.L27:
.long ___lshrsi3_r0
.size _really_dyn_rshift, .-_really_dyn_rshift
.ident "GCC: (GNU) 12.3.0"
With patch enabled, -O2 -ml
$ cat f.s
.file "f.c"
.text
.little
.text
.align 1
.align 2
.global _f_char_var
.type _f_char_var, @function
_f_char_var:
mov r4,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.size _f_char_var, .-_f_char_var
.align 1
.align 2
.global _f_unsigned_char_var
.type _f_unsigned_char_var, @function
_f_unsigned_char_var:
mov r4,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.size _f_unsigned_char_var, .-_f_unsigned_char_var
.align 1
.align 2
.global _f_symbol
.type _f_symbol, @function
_f_symbol:
mov.l .L5,r1
mov.b @r1,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.L6:
.align 2
.L5:
.long -65536
.size _f_symbol, .-_f_symbol
.align 1
.align 2
.global _f_symbol_zero
.type _f_symbol_zero, @function
_f_symbol_zero:
mov.l .L8,r1
mov.b @r1,r0
tst #64,r0
rts
movt r0
.L9:
.align 2
.L8:
.long -65536
.size _f_symbol_zero, .-_f_symbol_zero
.align 1
.align 2
.global _f_symbol_non_zero
.type _f_symbol_non_zero, @function
_f_symbol_non_zero:
mov.l .L11,r1
mov.b @r1,r0
tst #64,r0
mov #-1,r0
rts
negc r0,r0
.L12:
.align 2
.L11:
.long -65536
.size _f_symbol_non_zero, .-_f_symbol_non_zero
.align 1
.align 2
.global _dyn_lshift
.type _dyn_lshift, @function
_dyn_lshift:
mov.l .L15,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L16:
.align 2
.L15:
.long ___ashlsi3_r0
.size _dyn_lshift, .-_dyn_lshift
.align 1
.align 2
.global _dyn_rshift
.type _dyn_rshift, @function
_dyn_rshift:
mov.l .L19,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L20:
.align 2
.L19:
.long ___lshrsi3_r0
.size _dyn_rshift, .-_dyn_rshift
.align 1
.align 2
.global _really_dyn_lshift
.type _really_dyn_lshift, @function
_really_dyn_lshift:
mov.l .L23,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L24:
.align 2
.L23:
.long ___ashlsi3_r0
.size _really_dyn_lshift, .-_really_dyn_lshift
.align 1
.align 2
.global _really_dyn_rshift
.type _really_dyn_rshift, @function
_really_dyn_rshift:
mov.l .L27,r1
sts.l pr,@-r15
jsr @r1
mov r5,r0
lds.l @r15+,pr
rts
nop
.L28:
.align 2
.L27:
.long ___lshrsi3_r0
.size _really_dyn_rshift, .-_really_dyn_rshift
.ident "GCC: (GNU) 12.3.0"
> '-mdisable-dynshift-libcall' would be more appropriate for what it tries to
> do, I think. Although that is a whole different issue ... but what is it
> going to do for real dynamic shifts on SH2?
>
> What kind of code is it supposed to emit for things like
>
> unsigned int dyn_shift (unsigned int x, unsigned int y)
> {
> return x << (y & 31);
> }
As far as I understand from GCC sources, function I patched 'expand_ashiftrt'
process only constant values of shift. As you can see earlier, I added your and
other examples to tests. It looks like really dynamic shifts translate to
library calls.
Should I test more exotic situations? If so, could you please help me with
really exotic or weired examples?
