LoongArch: Redundant sign extension elimination optimization.

We found that the current combine optimization pass in gcc cannot handle
the following redundant sign extension situations:

(insn 77 76 78 5 (set (reg:SI 143)
        (plus:SI (subreg/s/u:SI (reg/v:DI 104 [ len ]) 0)
            (const_int 1 [0x1]))) {addsi3}
    (expr_list:REG_DEAD (reg/v:DI 104 [ len ])
        (nil)))
(insn 78 77 82 5 (set (reg/v:DI 104 [ len ])
        (sign_extend:DI (reg:SI 143))) {extendsidi2}
        (nil))

Because reg:SI 143 is not died or set in insn 78, no replacement merge will
be performed for the insn sequence. We adjusted the add template to eliminate
redundant sign extensions during the expand pass.
Adjusted based on upstream comments:
https://gcc.gnu.org/pipermail/gcc-patches/2024-January/641988.html

gcc/ChangeLog:

	* config/loongarch/loongarch.md (add<mode>3): Removed.
	(*addsi3): New.
	(addsi3): Ditto.
	(adddi3): Ditto.
	(*addsi3_extended): Removed.
	(addsi3_extended): New.

gcc/testsuite/ChangeLog:

	* gcc.target/loongarch/sign-extend.c: Moved to...
	* gcc.target/loongarch/sign-extend-1.c: ...here.
	* gcc.target/loongarch/sign-extend-2.c: New test.

0 files changed, 0 insertions, 0 deletions