[gcc r15-3634] AVR: Detect more skip opportunities.

[Georg-Johann Lay]

https://gcc.gnu.org/g:4ffca9966a9c43cedafe56d3ef8033182290f25b

commit r15-3634-g4ffca9966a9c43cedafe56d3ef8033182290f25b
Author: Georg-Johann Lay <avr@gjlay.de>
Date:   Fri Sep 13 18:06:57 2024 +0200

    AVR: Detect more skip opportunities.
    
    The transparent call insns like "*parityhi2.libgcc" output a single
    [R]CALL instruction that can be skipped by the skip instructions.
    Such insns have attribute "type" of "xcall" and can therefore
    be easily recognized.  Same applies when "adjust_len" is "call".
    
    gcc/
            * config/avr/avr.cc (avr_2word_insn_p): Return true for
            transparent calls: When insn attribute "type" is "xcall"
            or when "adjust_len" is "call".

Diff:
---
 gcc/config/avr/avr.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gcc/config/avr/avr.cc b/gcc/config/avr/avr.cc
index 48d1d0e76465..4cb51ea68dc7 100644
--- a/gcc/config/avr/avr.cc
+++ b/gcc/config/avr/avr.cc
@@ -12972,7 +12972,7 @@ test_hard_reg_class (enum reg_class rclass, rtx x)
 }
 
 
-/* Helper for jump_over_one_insn_p:  Test if INSN is a 2-word instruction
+/* Helper for `jump_over_one_insn_p':  Test if INSN is a 2-word instruction
    and thus is suitable to be skipped by CPSE, SBRC, etc.  */
 
 static bool
@@ -12986,7 +12986,10 @@ avr_2word_insn_p (rtx_insn *insn)
   switch (INSN_CODE (insn))
     {
     default:
-      return false;
+      return (recog_memoized (insn) >= 0
+	      // Transparent calls may be skipped.
+	      && (get_attr_type (insn) == TYPE_XCALL
+		  || get_attr_adjust_len (insn) == ADJUST_LEN_CALL));
 
     case CODE_FOR_movqi_insn:
     case CODE_FOR_movuqq_insn: