LoongArch: Optimize f{max,min}imum{,f}

The code now looks like:

	fclass.s        $fa2, $fa0
	movfr2gr.s      $t0, $fa2
	slli.w          $t0, $t0, 0x0
	fclass.s        $fa2, $fa1
	movfr2gr.s      $t1, $fa2
	or              $t0, $t0, $t1
	andi            $t0, $t0, 0x3
	bnez            $t0, 1f
	fmin.s          $fa0, $fa0, $fa1
	ret
	1:
	fmul.s		$fa0, $fa0, $fa1
	ret

This looks really bad, with expensive movfr2gr instructions, redundant
sign-extensions and masking (arguably it's a compiler
missed-optimzation), and a branch.  Rewrite it with inline assembly:

	fcmp.cor.s      $fcc0, $fa0, $fa0
	fcmp.cor.s      $fcc1, $fa1, $fa1
	fsel            $fa2, $fa0, $fa1, $fcc0
	fsel            $fa0, $fa1, $fa0, $fcc1
	fmax.s          $fa0, $fa2, $fa0
	ret

Note that we cannot make it more readable with
"double a = __builtin_isnanf (x) ? y : x" because this C statement only
happens to produce what we want with https://gcc.gnu.org/PR66462, if
this bug is fixed in the future the generated code may change.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>

0 files changed, 0 insertions, 0 deletions