[committed] Provide suitable output template for zero_extendqihi2 on H8

[committed] Provide suitable output template for zero_extendqihi2 on H8

[Jeff Law]

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Segher's recent combine change, quite unexpectedly, triggered a 
regression on the H8 port.  It failed to build newlib.

The zero_extendqihi2 pattern provided two alternatives.  One where the 
source and destination matched.  That turns into a suitable instruction 
trivially.   The second alternative was actually meant to capture cases 
where the value is coming from memory.

What was missing here was the reg->reg case where the source and 
destination do not match.  That fell into the second case which was 
requested to be split by the pattern's output template.

The splitter had a suitable condition to make sure it only triggered in 
the right cases.  Unfortunately with the pattern requiring a split in a 
case where the splitter was going to fail led to the fault.

So regardless of what's going on in the combiner, this code was just 
wrong.  Fixed thusly by providing a suitable output template for the 
reg->reg case.

Regression tested on h8300-elf.  Pushing to the trunk.

gcc/

	* config/h8300/extensions.md (zero_extendqihi*): Add output
	template for reg->reg case where the regs don't match.

Jeff

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commit c1e66532cbb424bd7ea8c3b2c1ffea4bb5233309
Author: Jeff Law <jlaw@ventanamicro.com>
Date:   Thu Mar 28 16:56:53 2024 -0600

    [committed] Provide suitable output template for zero_extendqihi2 on H8
    
    Segher's recent combine change, quite unexpectedly, triggered a regression on
    the H8 port.  It failed to build newlib.
    
    The zero_extendqihi2 pattern provided two alternatives.  One where the source
    and destination matched.  That turns into a suitable instruction trivially.
    The second alternative was actually meant to capture cases where the value is
    coming from memory.
    
    What was missing here was the reg->reg case where the source and destination do
    not match.  That fell into the second case which was requested to be split by
    the pattern's output template.
    
    The splitter had a suitable condition to make sure it only triggered in the
    right cases.  Unfortunately with the pattern requiring a split in a case where
    the splitter was going to fail led to the fault.
    
    So regardless of what's going on in the combiner, this code was just wrong.
    Fixed thusly by providing a suitable output template for the reg->reg case.
    
    Regression tested on h8300-elf.  Pushing to the trunk.
    
    gcc/
    
            * config/h8300/extensions.md (zero_extendqihi*): Add output
            template for reg->reg case where the regs don't match.

diff --git a/gcc/config/h8300/extensions.md b/gcc/config/h8300/extensions.md
index 7149dc0ac52..a1e8c4abd37 100644
--- a/gcc/config/h8300/extensions.md
+++ b/gcc/config/h8300/extensions.md
@@ -12,8 +12,8 @@ (define_expand "zero_extendqi<mode>2"
   })
 
 (define_insn_and_split "*zero_extendqihi2"
-  [(set (match_operand:HI 0 "register_operand" "=r,r")
-	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,g>")))]
+  [(set (match_operand:HI 0 "register_operand" "=r,r,r")
+	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,r,g>")))]
   ""
   "#"
   "&& reload_completed"
@@ -21,14 +21,15 @@ (define_insn_and_split "*zero_extendqihi2"
 	      (clobber (reg:CC CC_REG))])])
 
 (define_insn "*zero_extendqihi2<cczn>"
-  [(set (match_operand:HI 0 "register_operand" "=r,r")
-	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,g>")))
+  [(set (match_operand:HI 0 "register_operand" "=r,r,r")
+	(zero_extend:HI (match_operand:QI 1 "general_operand_src" "0,r,g>")))
    (clobber (reg:CC CC_REG))]
   ""
   "@
   extu.w	%T0
+  mov.b\t%X1,%R0\;extu.w\t%T0
   #"
-  [(set_attr "length" "2,10")])
+  [(set_attr "length" "2,4,10")])
 
 ;; Split the zero extension of a general operand (actually a memory
 ;; operand) into a load of the operand and the actual zero extension