From: Daniel Engel <g...@danielengel.com> In Thumb mode, the new functions are each 1-2 instructions smaller and faster, and branchless when the IT instruction is available. The ARM versions were converted to the "xxl/xxh" big-endian register convention, but are otherwise unchanged.
gcc/libgcc/ChangeLog: 2021-01-07 Daniel Engel <g...@danielengel.com> * config/arm/bits/shift.S: Faster thumb versions; updated big-endian register convention to "xxl/xxh". --- libgcc/config/arm/bits/shift.S | 327 +++++++++++++++++++++++---------- 1 file changed, 233 insertions(+), 94 deletions(-) diff --git a/libgcc/config/arm/bits/shift.S b/libgcc/config/arm/bits/shift.S index 94e466ac0d2..16cf2dcef04 100644 --- a/libgcc/config/arm/bits/shift.S +++ b/libgcc/config/arm/bits/shift.S @@ -1,102 +1,241 @@ +/* lshift.S: ARM optimized 64-bit integer shift + + Copyright (C) 2018-2021 Free Software Foundation, Inc. + Contributed by Daniel Engel, Senva Inc (g...@danielengel.com) + + This file is free software; you can redistribute it and/or modify it + under the terms of the GNU General Public License as published by the + Free Software Foundation; either version 3, or (at your option) any + later version. + + This file is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + Under Section 7 of GPL version 3, you are granted additional + permissions described in the GCC Runtime Library Exception, version + 3.1, as published by the Free Software Foundation. + + You should have received a copy of the GNU General Public License and + a copy of the GCC Runtime Library Exception along with this program; + see the files COPYING3 and COPYING.RUNTIME respectively. If not, see + <http://www.gnu.org/licenses/>. */ + #ifdef L_lshrdi3 - FUNC_START lshrdi3 - FUNC_ALIAS aeabi_llsr lshrdi3 - -#ifdef __thumb__ - lsrs al, r2 - movs r3, ah - lsrs ah, r2 - mov ip, r3 - subs r2, #32 - lsrs r3, r2 - orrs al, r3 - negs r2, r2 - mov r3, ip - lsls r3, r2 - orrs al, r3 - RET -#else - subs r3, r2, #32 - rsb ip, r2, #32 - movmi al, al, lsr r2 - movpl al, ah, lsr r3 - orrmi al, al, ah, lsl ip - mov ah, ah, lsr r2 - RET -#endif - FUNC_END aeabi_llsr - FUNC_END lshrdi3 - -#endif - +// long long __aeabi_llsr(long long, int) +// Logical shift right the 64 bit value in $r1:$r0 by the count in $r2. +// The result is only guaranteed for shifts in the range of '0' to '63'. +// Uses $r3 as scratch space. +FUNC_START_SECTION aeabi_llsr .text.sorted.libgcc.lshrdi3 +FUNC_ALIAS lshrdi3 aeabi_llsr + CFI_START_FUNCTION + + #if defined(__thumb__) && __thumb__ + + // Save a copy for the remainder. + movs r3, xxh + + // Assume a simple shift. + lsrs xxl, r2 + lsrs xxh, r2 + + // Test if the shift distance is larger than 1 word. + subs r2, #32 + + #ifdef __HAVE_FEATURE_IT + do_it lo,te + + // The remainder is opposite the main shift, (32 - x) bits. + rsblo r2, #0 + lsllo r3, r2 + + // The remainder shift extends into the hi word. + lsrhs r3, r2 + + #else /* !__HAVE_FEATURE_IT */ + bhs LLSYM(__llsr_large) + + // The remainder is opposite the main shift, (32 - x) bits. + rsbs r2, #0 + lsls r3, r2 + + // Cancel any remaining shift. + eors r2, r2 + + LLSYM(__llsr_large): + // Apply any remaining shift to the hi word. + lsrs r3, r2 + + #endif /* !__HAVE_FEATURE_IT */ + + // Merge remainder and result. + adds xxl, r3 + RET + + #else /* !__thumb__ */ + + subs r3, r2, #32 + rsb ip, r2, #32 + movmi xxl, xxl, lsr r2 + movpl xxl, xxh, lsr r3 + orrmi xxl, xxl, xxh, lsl ip + mov xxh, xxh, lsr r2 + RET + + #endif /* !__thumb__ */ + + + CFI_END_FUNCTION +FUNC_END lshrdi3 +FUNC_END aeabi_llsr + +#endif /* L_lshrdi3 */ + + #ifdef L_ashrdi3 - - FUNC_START ashrdi3 - FUNC_ALIAS aeabi_lasr ashrdi3 - -#ifdef __thumb__ - lsrs al, r2 - movs r3, ah - asrs ah, r2 - subs r2, #32 - @ If r2 is negative at this point the following step would OR - @ the sign bit into all of AL. That's not what we want... - bmi 1f - mov ip, r3 - asrs r3, r2 - orrs al, r3 - mov r3, ip -1: - negs r2, r2 - lsls r3, r2 - orrs al, r3 - RET -#else - subs r3, r2, #32 - rsb ip, r2, #32 - movmi al, al, lsr r2 - movpl al, ah, asr r3 - orrmi al, al, ah, lsl ip - mov ah, ah, asr r2 - RET -#endif - - FUNC_END aeabi_lasr - FUNC_END ashrdi3 - -#endif + +// long long __aeabi_lasr(long long, int) +// Arithmetic shift right the 64 bit value in $r1:$r0 by the count in $r2. +// The result is only guaranteed for shifts in the range of '0' to '63'. +// Uses $r3 as scratch space. +FUNC_START_SECTION aeabi_lasr .text.sorted.libgcc.ashrdi3 +FUNC_ALIAS ashrdi3 aeabi_lasr + CFI_START_FUNCTION + + #if defined(__thumb__) && __thumb__ + + // Save a copy for the remainder. + movs r3, xxh + + // Assume a simple shift. + lsrs xxl, r2 + asrs xxh, r2 + + // Test if the shift distance is larger than 1 word. + subs r2, #32 + + #ifdef __HAVE_FEATURE_IT + do_it lo,te + + // The remainder is opposite the main shift, (32 - x) bits. + rsblo r2, #0 + lsllo r3, r2 + + // The remainder shift extends into the hi word. + asrhs r3, r2 + + #else /* !__HAVE_FEATURE_IT */ + bhs LLSYM(__lasr_large) + + // The remainder is opposite the main shift, (32 - x) bits. + rsbs r2, #0 + lsls r3, r2 + + // Cancel any remaining shift. + eors r2, r2 + + LLSYM(__lasr_large): + // Apply any remaining shift to the hi word. + asrs r3, r2 + + #endif /* !__HAVE_FEATURE_IT */ + + // Merge remainder and result. + adds xxl, r3 + RET + + #else /* !__thumb__ */ + + subs r3, r2, #32 + rsb ip, r2, #32 + movmi xxl, xxl, lsr r2 + movpl xxl, xxh, asr r3 + orrmi xxl, xxl, xxh, lsl ip + mov xxh, xxh, asr r2 + RET + + #endif /* !__thumb__ */ + + CFI_END_FUNCTION +FUNC_END ashrdi3 +FUNC_END aeabi_lasr + +#endif /* L_ashrdi3 */ + #ifdef L_ashldi3 - FUNC_START ashldi3 - FUNC_ALIAS aeabi_llsl ashldi3 - -#ifdef __thumb__ - lsls ah, r2 - movs r3, al - lsls al, r2 - mov ip, r3 - subs r2, #32 - lsls r3, r2 - orrs ah, r3 - negs r2, r2 - mov r3, ip - lsrs r3, r2 - orrs ah, r3 - RET -#else - subs r3, r2, #32 - rsb ip, r2, #32 - movmi ah, ah, lsl r2 - movpl ah, al, lsl r3 - orrmi ah, ah, al, lsr ip - mov al, al, lsl r2 - RET -#endif - FUNC_END aeabi_llsl - FUNC_END ashldi3 - -#endif +// long long __aeabi_llsl(long long, int) +// Logical shift left the 64 bit value in $r1:$r0 by the count in $r2. +// The result is only guaranteed for shifts in the range of '0' to '63'. +// Uses $r3 as scratch space. +.section .text.sorted.libgcc.ashldi3,"x" +FUNC_START_SECTION aeabi_llsl .text.sorted.libgcc.ashldi3 +FUNC_ALIAS ashldi3 aeabi_llsl + CFI_START_FUNCTION + + #if defined(__thumb__) && __thumb__ + + // Save a copy for the remainder. + movs r3, xxl + + // Assume a simple shift. + lsls xxl, r2 + lsls xxh, r2 + + // Test if the shift distance is larger than 1 word. + subs r2, #32 + + #ifdef __HAVE_FEATURE_IT + do_it lo,te + + // The remainder is opposite the main shift, (32 - x) bits. + rsblo r2, #0 + lsrlo r3, r2 + + // The remainder shift extends into the hi word. + lslhs r3, r2 + + #else /* !__HAVE_FEATURE_IT */ + bhs LLSYM(__llsl_large) + + // The remainder is opposite the main shift, (32 - x) bits. + rsbs r2, #0 + lsrs r3, r2 + + // Cancel any remaining shift. + eors r2, r2 + + LLSYM(__llsl_large): + // Apply any remaining shift to the hi word. + lsls r3, r2 + + #endif /* !__HAVE_FEATURE_IT */ + + // Merge remainder and result. + adds xxh, r3 + RET + + #else /* !__thumb__ */ + + subs r3, r2, #32 + rsb ip, r2, #32 + movmi xxh, xxh, lsl r2 + movpl xxh, xxl, lsl r3 + orrmi xxh, xxh, xxl, lsr ip + mov xxl, xxl, lsl r2 + RET + + #endif /* !__thumb__ */ + + CFI_END_FUNCTION +FUNC_END ashldi3 +FUNC_END aeabi_llsl + +#endif /* L_ashldi3 */ + + -- 2.25.1