From: Wolfgang Hospital <Wolfgang.Hospital@arcor.de>
Date: Sat, 18 May 2024 13:02:51 +0000 (+0200)
Subject: AVR: target/115065 - Tweak __clzhi2.
X-Git-Tag: basepoints/gcc-16~8908
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=988838da722dea09bd81ee9d49800a6f24980372;p=thirdparty%2Fgcc.git

AVR: target/115065 - Tweak __clzhi2.

The libgcc implementation of __clzhi2 can be tweaked by
one cycle in some situations by re-arranging the instructions.
It also reduces the WCET by 1 cycle.

libgcc/
	PR target/115065
	* config/avr/lib1funcs.S (__clzhi2): Tweak.
---

diff --git a/libgcc/config/avr/lib1funcs.S b/libgcc/config/avr/lib1funcs.S
index 04a4eb01ab4..d48b04747da 100644
--- a/libgcc/config/avr/lib1funcs.S
+++ b/libgcc/config/avr/lib1funcs.S
@@ -2921,11 +2921,9 @@ DEFUN __clzhi2
     clr  r26
     tst  r25
     brne 1f
-    subi r26, -8
     or   r25, r24
-    brne 1f
-    ldi  r24, 16
-    ret
+    breq 0f
+    subi r26, -8
 1:  cpi  r25, 16
     brsh 3f
     subi r26, -3
@@ -2936,6 +2934,8 @@ DEFUN __clzhi2
     mov  r24, r26
     clr  r25
     ret
+0:  ldi  r24, 16
+    ret
 ENDF __clzhi2
 #endif /* defined (L_clzhi2) */