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[avr,applied] PR115065: Tweak __clzhi2

Message ID 3b03c4ff-f133-44a3-9561-113e2c4545b6@gjlay.de
State New
Headers show
Series [avr,applied] PR115065: Tweak __clzhi2 | expand

Commit Message

Georg-Johann Lay May 18, 2024, 1:19 p.m. UTC 
Applied as obvious,

Johann

--

Author: Wolfgang Hospital <Wolfgang.Hospital@arcor.de>
Date:   Sat May 18 15:02:51 2024 +0200

     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.
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Patch

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) */