From 7b672c1503abffcc83a30a9731419539f52ac73f Mon Sep 17 00:00:00 2001 From: Zack Rusin Date: Thu, 18 Jul 2013 02:38:54 -0400 Subject: [PATCH] gallivm: fix edge cases in exp2 exp(0) has to be exactly 1, exp(-inf) has to be 0, exp(inf) has to be inf and exp(nan) has to be nan, this fixes all of those cases. Signed-off-by: Zack Rusin Reviewed-by: Jose Fonseca Reviewed-by: Roland Scheidegger --- src/gallium/auxiliary/gallivm/lp_bld_arit.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c index d2d91f50da9..34e3ed94542 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c +++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c @@ -3141,7 +3141,7 @@ lp_build_polynomial(struct lp_build_context *bld, */ const double lp_build_exp2_polynomial[] = { #if EXP_POLY_DEGREE == 5 - 0.999999925063526176901, + 1.000000000000000000000, /*XXX: was 0.999999925063526176901, recompute others */ 0.693153073200168932794, 0.240153617044375388211, 0.0558263180532956664775, @@ -3196,8 +3196,12 @@ lp_build_exp2_approx(struct lp_build_context *bld, assert(type.floating && type.width == 32); - x = lp_build_min(bld, x, lp_build_const_vec(bld->gallivm, type, 129.0)); - x = lp_build_max(bld, x, lp_build_const_vec(bld->gallivm, type, -126.99999)); + /* We want to preserve NaN and make sure than for exp2 if x > 128, + * the result is INF and if it's smaller than -126.9 the result is 0 */ + x = lp_build_min_ext(bld, lp_build_const_vec(bld->gallivm, type, 128.0), x, + GALLIVM_NAN_RETURN_SECOND); + x = lp_build_max_ext(bld, lp_build_const_vec(bld->gallivm, type, -126.99999), x, + GALLIVM_NAN_RETURN_SECOND); /* ipart = floor(x) */ /* fpart = x - ipart */ -- 2.30.2