diff options
| -rw-r--r-- | src/gallium/auxiliary/gallivm/lp_bld_arit.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_arit.c b/src/gallium/auxiliary/gallivm/lp_bld_arit.c index 02fb81afe51..c4931c0b230 100644 --- a/src/gallium/auxiliary/gallivm/lp_bld_arit.c +++ b/src/gallium/auxiliary/gallivm/lp_bld_arit.c @@ -2707,11 +2707,11 @@ lp_build_sqrt(struct lp_build_context *bld, /** * Do one Newton-Raphson step to improve reciprocate precision: * - * x_{i+1} = x_i * (2 - a * x_i) + * x_{i+1} = x_i + x_i * (1 - a * x_i) * * XXX: Unfortunately this won't give IEEE-754 conformant results for 0 or * +/-Inf, giving NaN instead. Certain applications rely on this behavior, - * such as Google Earth, which does RCP(RSQRT(0.0) when drawing the Earth's + * such as Google Earth, which does RCP(RSQRT(0.0)) when drawing the Earth's * halo. It would be necessary to clamp the argument to prevent this. * * See also: @@ -2724,12 +2724,12 @@ lp_build_rcp_refine(struct lp_build_context *bld, LLVMValueRef rcp_a) { LLVMBuilderRef builder = bld->gallivm->builder; - LLVMValueRef two = lp_build_const_vec(bld->gallivm, bld->type, 2.0); + LLVMValueRef neg_a; LLVMValueRef res; - res = LLVMBuildFMul(builder, a, rcp_a, ""); - res = LLVMBuildFSub(builder, two, res, ""); - res = LLVMBuildFMul(builder, rcp_a, res, ""); + neg_a = LLVMBuildFNeg(builder, a, ""); + res = lp_build_fmuladd(builder, neg_a, rcp_a, bld->one); + res = lp_build_fmuladd(builder, res, rcp_a, rcp_a); return res; } |