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.
Jeffcommit c1e66532cbb424bd7ea8c3b2c1ffea4bb5233309
Author: Jeff Law <j...@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
