[PATCH] [RISC-V] Tune for removal unnecessary sext in builtin overflows [PR108016]

It fixes one of the PR108016 mis-optimization.

The patch adjusts expanding for __builtin_add/sub_overflow() on RV64 targets
to avoid unnecessary sext.w instructions.

It replaces expanded for ADD/SUB_OVERFLOW code:
  r141:SI=r139:DI#0+r140:DI#0 .. r143:DI=sign_extend(r141:SI)
to the followong kind of chain ->
  r143:DI=sign_extend(r139:DI#0+r140:DI#0) .. r141:SI=r143:DI#0
so that sign_extend(a:SI+b:SI) to be emitted as addw (or subw) instruction,
while output r141:SI register will be placed at the end of chain without
extra dependencies, and thus could be easily optimized-out by further pipeline.

	PR middle-end/108016
gcc/ChangeLog:

	* config/riscv/riscv.md (addv<mode>4, uaddv<mode>4, subv<mode>4,
	usubv<mode>4): Tunes for unnecessary sext.w elimination.

	PR middle-end/108016
gcc/testsuite/ChangeLog:

	* gcc.target/riscv/pr108016.c: New test.

0 files changed, 0 insertions, 0 deletions