From e216951f509b71da193da2fc63e25b998740d58b Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Wed, 15 May 2013 23:08:52 +0000 Subject: math: use double_t for temporaries to avoid stores on i386 When FLT_EVAL_METHOD!=0 (only i386 with x87 fp) the excess precision of an expression must be removed in an assignment. (gcc needs -fexcess-precision=standard or -std=c99 for this) This is done by extra load/store instructions which adds code bloat when lot of temporaries are used and it makes the result less precise in many cases. Using double_t and float_t avoids these issues on i386 and it makes no difference on other archs. For now only a few functions are modified where the excess precision is clearly beneficial (mostly polynomial evaluations with temporaries). object size differences on i386, gcc-4.8: old new __cosdf.o 123 95 __cos.o 199 169 __sindf.o 131 95 __sin.o 225 203 __tandf.o 207 151 __tan.o 605 499 erff.o 1470 1416 erf.o 1703 1649 j0f.o 1779 1745 j0.o 2308 2274 j1f.o 1602 1568 j1.o 2286 2252 tgamma.o 1431 1424 math/*.o 64164 63635 --- src/math/__cos.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/math/__cos.c') diff --git a/src/math/__cos.c b/src/math/__cos.c index 8699c1d5..46cefb38 100644 --- a/src/math/__cos.c +++ b/src/math/__cos.c @@ -60,7 +60,7 @@ C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */ double __cos(double x, double y) { - double hz,z,r,w; + double_t hz,z,r,w; z = x*x; w = z*z; -- cgit v1.2.1