[gcc r14-365] [Committed] Update xstormy16's neghi2 pattern to not clobber the carry flag.

[gcc r14-365] [Committed] Update xstormy16's neghi2 pattern to not clobber the carry flag.

[Roger Sayle]

https://gcc.gnu.org/g:b159026b739f46e6d552bb23e8f51f03e291f51e

commit r14-365-gb159026b739f46e6d552bb23e8f51f03e291f51e
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Sun Apr 30 23:47:13 2023 +0100

    [Committed] Update xstormy16's neghi2 pattern to not clobber the carry flag.
    
    When I converted xstormy's neghi2 pattern from a define_expand to a
    define_insn, I forgot that define_expand implicitly produces a
    sequence of instructions, but a define_insn is an implicit parallel,
    thereby messing up the clobber (reg:BI CARRY_REG), which can then cause
    an ICE in the auto-generated added_clobbers_hard_reg_p.  Whilst stripping
    the superfluous PARALLEL resolves this issue, an even better fix is to
    use xstormy16's INC instruction, that (like NOT) doesn't affect the carry
    flag, resulting in a neghi2 implementation that can more easily be CSE'd
    and scheduled.
    
    Many thanks (again) to Jeff Law for testing/reporting this issue.
    
    2024-04-30  Roger Sayle  <roger@nextmovesoftware.com>
    
    gcc/ChangeLog
            * config/stormy16/stormy16.md (neghi2): Rewrite pattern using
            inc to avoid clobbering the carry flag.
    
    gcc/testsuite/ChangeLog
            * gcc.target/xstormy16/neghi2.c: Update expected implementation.

Diff:
---
 gcc/config/stormy16/stormy16.md             | 7 +++----
 gcc/testsuite/gcc.target/xstormy16/neghi2.c | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/gcc/config/stormy16/stormy16.md b/gcc/config/stormy16/stormy16.md
index be1ee04e5b5..91e4bb1cff7 100644
--- a/gcc/config/stormy16/stormy16.md
+++ b/gcc/config/stormy16/stormy16.md
@@ -519,11 +519,10 @@
 ;; Negation
 
 (define_insn "neghi2"
-  [(parallel [(set (match_operand:HI 0 "register_operand" "=r")
-		   (neg:HI (match_operand:HI 1 "register_operand" "0")))
-	      (clobber (reg:BI CARRY_REG))])]
+  [(set (match_operand:HI 0 "register_operand" "=r")
+	(neg:HI (match_operand:HI 1 "register_operand" "0")))]
   ""
-  "not %0 | add %0,#1"
+  "not %0 | inc %0"
   [(set_attr "length" "4")])
 \f
 ;; ::::::::::::::::::::
diff --git a/gcc/testsuite/gcc.target/xstormy16/neghi2.c b/gcc/testsuite/gcc.target/xstormy16/neghi2.c
index dd3dd1e60fb..101c6da279f 100644
--- a/gcc/testsuite/gcc.target/xstormy16/neghi2.c
+++ b/gcc/testsuite/gcc.target/xstormy16/neghi2.c
@@ -5,4 +5,4 @@ short neg(short x)
 {
   return -x;
 }
-/* { dg-final { scan-assembler "not r2 | add r2,#1" } } */
+/* { dg-final { scan-assembler "not r2 | inc r2" } } */