The Thumb versions of these 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
naming convention, but are otherwise unchanged.
gcc/libgcc/ChangeLog:
2021-01-13 Daniel Engel <g...@danielengel.com>
* config/arm/bits/shift.S (__ashldi3, __ashrdi3, __lshldi3):
Reduced code size on Thumb architectures;
updated big-endian register naming convention to "xxl/xxh".
---
libgcc/config/arm/eabi/lshift.S | 338 +++++++++++++++++++++-----------
1 file changed, 228 insertions(+), 110 deletions(-)
diff --git a/libgcc/config/arm/eabi/lshift.S b/libgcc/config/arm/eabi/lshift.S
index 0974a72c377..16cf2dcef04 100644
--- a/libgcc/config/arm/eabi/lshift.S
+++ b/libgcc/config/arm/eabi/lshift.S
@@ -1,123 +1,241 @@
-/* Copyright (C) 1995-2021 Free Software Foundation, Inc.
+/* lshift.S: ARM optimized 64-bit integer shift
-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.
+ Copyright (C) 2018-2021 Free Software Foundation, Inc.
+ Contributed by Daniel Engel, Senva Inc (g...@danielengel.com)
-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.
+ 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.
-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.
+ 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.
-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/>. */
+ 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
