https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49263
--- Comment #45 from Alexander Klepikov <klepikov.alex+bugs at gmail dot com>
---
>I have an idea. If it's impossible to defer initial optimization,
> maybe it's possible to emit some intermediate insn and catch it and optimize
> later?
Good news. I've made a proof of concept. It works at least sometimes - on
simple tests.
$ cat f.c
#define A 0xFFFF0000
#define P ((unsigned char *)A)
#define F 64
#define S 8
unsigned char f_non_zero(unsigned char v){
return (v & F) != 0;
}
unsigned f_sym_non_zero(void){
return (*P & F) != 0;
}
unsigned f_sym_mask(void){
return (*P & F) == F;
}
int f_rshift(char v){
return v >> S;
}
$ /usr/local/sh-toolchain/bin/sh-elf-gcc -O2 -mb -m2e -da -S f.c
$ cat f.s
.file "f.c"
.text
.text
.align 1
.align 2
.global _f_non_zero
.type _f_non_zero, @function
_f_non_zero:
mov r4,r0
sts.l pr,@-r15
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.size _f_non_zero, .-_f_non_zero
.align 1
.align 2
.global _f_sym_non_zero
.type _f_sym_non_zero, @function
_f_sym_non_zero:
mov.l .L6,r1
sts.l pr,@-r15
mov.b @r1,r0
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.L7:
.align 2
.L6:
.long -65536
.size _f_sym_non_zero, .-_f_sym_non_zero
.align 1
.align 2
.global _f_sym_mask
.type _f_sym_mask, @function
_f_sym_mask:
mov.l .L10,r1
sts.l pr,@-r15
mov.b @r1,r0
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.L11:
.align 2
.L10:
.long -65536
.size _f_sym_mask, .-_f_sym_mask
.align 1
.align 2
.global _f_rshift
.type _f_rshift, @function
_f_rshift:
mov.l .L14,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
lds.l @r15+,pr
rts
nop
.L15:
.align 2
.L14:
.long ___ashiftrt_r4_8
.size _f_rshift, .-_f_rshift
.ident "GCC: (GNU) 13.1.0"
$ /usr/local/sh-toolchain/bin/sh-elf-gcc -O2 -ml -m2e -da -S f.c
$ cat f.s
.file "f.c"
.text
.little
.text
.align 1
.align 2
.global _f_non_zero
.type _f_non_zero, @function
_f_non_zero:
mov r4,r0
sts.l pr,@-r15
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.size _f_non_zero, .-_f_non_zero
.align 1
.align 2
.global _f_sym_non_zero
.type _f_sym_non_zero, @function
_f_sym_non_zero:
mov.l .L6,r1
sts.l pr,@-r15
mov.b @r1,r0
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.L7:
.align 2
.L6:
.long -65536
.size _f_sym_non_zero, .-_f_sym_non_zero
.align 1
.align 2
.global _f_sym_mask
.type _f_sym_mask, @function
_f_sym_mask:
mov.l .L10,r1
sts.l pr,@-r15
mov.b @r1,r0
tst #64,r0
mov #-1,r0
negc r0,r0
lds.l @r15+,pr
rts
nop
.L11:
.align 2
.L10:
.long -65536
.size _f_sym_mask, .-_f_sym_mask
.align 1
.align 2
.global _f_rshift
.type _f_rshift, @function
_f_rshift:
mov.l .L14,r1
sts.l pr,@-r15
jsr @r1
exts.b r4,r4
mov r4,r0
lds.l @r15+,pr
rts
nop
.L15:
.align 2
.L14:
.long ___ashiftrt_r4_8
.size _f_rshift, .-_f_rshift
.ident "GCC: (GNU) 13.1.0"
Splitting takes place at split1 pass as expected. Here is the patch itself.
$ cat gcc-13.1.0-ashrsi3_libcall.patch
diff -ur gcc-13.1.0.orig/gcc/config/sh/sh-protos.h
gcc-13.1.0/gcc/config/sh/sh-protos.h
--- gcc-13.1.0.orig/gcc/config/sh/sh-protos.h 2023-04-26 10:09:39.000000000
+0300
+++ gcc-13.1.0/gcc/config/sh/sh-protos.h 2023-05-29 11:45:05.134723435
+0300
@@ -78,6 +78,7 @@
extern void gen_shifty_op (int, rtx *);
extern void gen_shifty_hi_op (int, rtx *);
extern bool expand_ashiftrt (rtx *);
+extern bool expand_ashrsi3_libcall (rtx *);//delete
extern bool sh_dynamicalize_shift_p (rtx);
extern int shl_and_kind (rtx, rtx, int *);
extern int shl_and_length (rtx);
diff -ur gcc-13.1.0.orig/gcc/config/sh/sh.cc gcc-13.1.0/gcc/config/sh/sh.cc
--- gcc-13.1.0.orig/gcc/config/sh/sh.cc 2023-04-26 10:09:39.000000000 +0300
+++ gcc-13.1.0/gcc/config/sh/sh.cc 2023-05-29 17:09:54.602787537 +0300
@@ -3875,11 +3877,37 @@
wrk = gen_reg_rtx (Pmode);
/* Load the value into an arg reg and call a helper. */
- emit_move_insn (gen_rtx_REG (SImode, 4), operands[1]);
+ /*emit_move_insn (gen_rtx_REG (SImode, 4), operands[1]);
sprintf (func, "__ashiftrt_r4_%d", value);
rtx lab = function_symbol (wrk, func, SFUNC_STATIC).lab;
emit_insn (gen_ashrsi3_n (GEN_INT (value), wrk, lab));
emit_move_insn (operands[0], gen_rtx_REG (SImode, 4));
+ return true;*/
+
+ if (dump_file)
+ fprintf(dump_file, "ashrsi3: Emitting collapsed libcall\n");
+ emit_insn (gen_ashrsi3_libcall_collapsed (operands[0], operands[1],
GEN_INT(value)));//delete
+ return true;//delete
+}
+
+//delete
+bool
+expand_ashrsi3_libcall (rtx *operands) {
+ char func[18];
+
+ if (dump_file)
+ fprintf(dump_file, "ashrsi3_libcall_collapsed: Expanding ashrsi3
libcall\n");
+
+ rtx wrk = gen_reg_rtx (Pmode);
+ emit_move_insn (gen_rtx_REG (SImode, 4), operands[1]);
+
+ sprintf (func, "__ashiftrt_r4_%d", INTVAL (operands[2]));
+
+ rtx lab = function_symbol (wrk, func, SFUNC_STATIC).lab;
+
+ emit_insn (gen_ashrsi3_n (operands[2], wrk, lab));
+ emit_move_insn (operands[0], gen_rtx_REG (SImode, 4));
+
return true;
}
diff -ur gcc-13.1.0.orig/gcc/config/sh/sh.md gcc-13.1.0/gcc/config/sh/sh.md
--- gcc-13.1.0.orig/gcc/config/sh/sh.md 2023-04-26 10:09:39.000000000 +0300
+++ gcc-13.1.0/gcc/config/sh/sh.md 2023-05-29 17:10:42.752779922 +0300
@@ -3867,6 +3867,35 @@
[(set_attr "type" "sfunc")
(set_attr "needs_delay_slot" "yes")])
+(define_insn "ashrsi3_libcall_collapsed"
+ [(set (match_operand:SI 0 "arith_reg_dest" "=r")
+ (ashiftrt:SI (match_operand:SI 1 "arith_reg_operand" "0")
+ (match_operand:SI 2 "const_int_operand")))
+ (clobber (reg:SI T_REG))
+ (clobber (reg:SI PR_REG))]
+ "TARGET_SH1"
+ "OOPS"
+ [(set_attr "type" "dyn_shift")
+ (set_attr "needs_delay_slot" "yes")])
+
+(define_insn_and_split "ashrsi3_libcall_expand"
+ [(parallel [(set (match_operand:SI 0 "arith_reg_dest")
+ (ashiftrt:SI (match_operand:SI 1 "arith_reg_operand")
+ (match_operand:SI 2 "const_int_operand"))
+ )(clobber (reg:SI T_REG))
+ (clobber (reg:SI PR_REG))
+ ])]
+ "TARGET_SH1"
+ "OOPS_1"
+ "&& 1"
+ [(const_int 0)]
+{
+ if (expand_ashrsi3_libcall(operands))
+ DONE;
+ else
+ FAIL;
+})
+
;; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
;; DImode arithmetic shift right
I did it by feel, actually picking up the parameters until it worked. So please
check it and improve it because I'm sure it will break something. Thank you.
