From: Andrew Pinski <pins...@gmail.com>
On targets with native copysign instructions, (copysign x, -1) is
usually more efficient than (fneg (fabs x)). Since r14-5284, in the
middle end we always optimize (fneg (fabs x)) to (copysign x, -1), not
vice versa. If the target does not support native fcopysign,
expand_COPYSIGN will expand it as (fneg (fabs x)) anyway.
gcc/ChangeLog:
PR rtl-optimization/112483
* simplify-rtx.cc (simplify_binary_operation_1) <case COPYSIGN>:
Call simplify_unary_operation for NEG instead of
simplify_gen_unary.
---
[xry111]:
Following Andrew's suggestion, I bootstrapped and regtested this
patch on loongarch64-linux-gnu. Now with
float t(float x)
{
return __builtin_copysignf(x, -0.1234);
}
It correctly generates
pcalau12i $r12,%pc_hi20(.LC0)
fld.s $f1,$r12,%pc_lo12(.LC0)
fcopysign.s $f0,$f0,$f1
jr $r1
instead of the de-optimized fabs.s and fneg.s
Ok for trunk?
gcc/simplify-rtx.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 2d2e5a3c1ca..f3745d86aea 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -4392,7 +4392,7 @@ simplify_ashift:
real_convert (&f1, mode, CONST_DOUBLE_REAL_VALUE (trueop1));
rtx tmp = simplify_gen_unary (ABS, mode, op0, mode);
if (REAL_VALUE_NEGATIVE (f1))
- tmp = simplify_gen_unary (NEG, mode, tmp, mode);
+ tmp = simplify_unary_operation (NEG, mode, tmp, mode);
return tmp;
}
if (GET_CODE (op0) == NEG || GET_CODE (op0) == ABS)
--
2.42.1
