https://gcc.gnu.org/g:29cc92348e0d32b7d301eae42aaebd716736f037
commit r15-9248-g29cc92348e0d32b7d301eae42aaebd716736f037
Author: Georg-Johann Lay <a...@gjlay.de>
Date: Mon Apr 7 12:39:41 2025 +0200
AVRrc: Tweak __[u]mulhisi3.
When MUL is not available, then the __umulhisi3 and __mulhisi3
functions can use __mulhisi3_helper. This improves code size,
stack footprint and runtime on AVRrc.
libgcc/
* config/avr/lib1funcs.S (__mulhisi3, __umulhisi3): Use
__mulhisi3_helper for better performance on AVRrc.
Diff:
---
libgcc/config/avr/lib1funcs.S | 71 ++++++++++++++-----------------------------
1 file changed, 22 insertions(+), 49 deletions(-)
diff --git a/libgcc/config/avr/lib1funcs.S b/libgcc/config/avr/lib1funcs.S
index 52ce051e00fe..dfe99b1ea06f 100644
--- a/libgcc/config/avr/lib1funcs.S
+++ b/libgcc/config/avr/lib1funcs.S
@@ -395,29 +395,23 @@ ENDF __mulhi3
#if defined (L_umulhisi3)
DEFUN __umulhisi3
-#ifndef __AVR_TINY__
+#ifdef __AVR_TINY__
+ ;; Save callee saved regs.
+ push B0
+ push B1
+#endif /* AVR_TINY */
wmov B0, 24
;; Zero-extend B
clr B2
clr B3
;; Zero-extend A
wmov A2, B2
- XJMP __mulsi3
+#ifdef __AVR_TINY__
+ ;; Clear hi16 of the result so we can use __mulsi3_helper.
+ wmov CC2, B2
+ XJMP __mulsi3_helper
#else
- ;; Push zero-extended R24
- push __zero_reg__
- push __zero_reg__
- push r25
- push r24
- ;; Zero-extend R22
- clr R24
- clr R25
- XCALL __mulsi3
- pop __tmp_reg__
- pop __tmp_reg__
- pop __tmp_reg__
- pop __tmp_reg__
- ret
+ XJMP __mulsi3
#endif /* AVR_TINY? */
ENDF __umulhisi3
#endif /* L_umulhisi3 */
@@ -425,54 +419,33 @@ ENDF __umulhisi3
#if defined (L_mulhisi3)
DEFUN __mulhisi3
#ifdef __AVR_TINY__
- ;; Push sign-extended R24
- mov __tmp_reg__, r25
- lsl __tmp_reg__
- sbc __tmp_reg__, __tmp_reg__
- push __tmp_reg__
- push __tmp_reg__
- push r25
- push r24
- ;; Sign-extend R22
- mov r24, r23
- lsl r24
- sbc r24, r24
- sbc r25, r25
- XCALL __mulsi3
- pop __tmp_reg__
- pop __tmp_reg__
- pop __tmp_reg__
- pop __tmp_reg__
- ret
-#else
+ ;; Save callee saved regs.
+ push B0
+ push B1
+#endif /* AVR_TINY */
wmov B0, 24
;; Sign-extend B
lsl r25
sbc B2, B2
mov B3, B2
-#ifdef __AVR_ERRATA_SKIP_JMP_CALL__
- ;; Sign-extend A
- clr A2
- sbrc A1, 7
- com A2
- mov A3, A2
- XJMP __mulsi3
-#else /* no __AVR_ERRATA_SKIP_JMP_CALL__ */
;; Zero-extend A and __mulsi3 will run at least twice as fast
;; compared to a sign-extended A.
clr A2
clr A3
+ ;; Clear hi16 of the result so we can use __mulsi3_helper.
+ wmov CC2, A2
sbrs A1, 7
- XJMP __mulsi3
+#ifdef __AVR_ERRATA_SKIP_JMP_CALL__
+ rjmp 1f
+#else
+ XJMP __mulsi3_helper
+#endif /* ERRATA_SKIP */
;; If A < 0 then perform the B * 0xffff.... before the
;; very multiplication by initializing the high part of the
;; result CC with -B.
- wmov CC2, A2
sub CC2, B0
sbc CC3, B1
- XJMP __mulsi3_helper
-#endif /* __AVR_ERRATA_SKIP_JMP_CALL__ */
-#endif /* AVR_TINY? */
+1: XJMP __mulsi3_helper
ENDF __mulhisi3
#endif /* L_mulhisi3 */
