Mesa (master): gallivm: Special bri-linear computation path for unmodified rho.
Jose Fonseca
jrfonseca at kemper.freedesktop.org
Sat Oct 9 11:13:26 UTC 2010
Module: Mesa
Branch: master
Commit: 679dd26623a53b5a052845bf4c6aef224cfdd5a2
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=679dd26623a53b5a052845bf4c6aef224cfdd5a2
Author: José Fonseca <jfonseca at vmware.com>
Date: Sat Oct 9 12:12:03 2010 +0100
gallivm: Special bri-linear computation path for unmodified rho.
---
src/gallium/auxiliary/gallivm/lp_bld_sample.c | 111 ++++++++++++++++++++-----
1 files changed, 91 insertions(+), 20 deletions(-)
diff --git a/src/gallium/auxiliary/gallivm/lp_bld_sample.c b/src/gallium/auxiliary/gallivm/lp_bld_sample.c
index 5bc3c26..43ea8b1 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_sample.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_sample.c
@@ -294,31 +294,30 @@ lp_build_rho(struct lp_build_sample_context *bld,
* TODO: This could be done in fixed point, where applicable.
*/
static void
-lp_build_brilinear_lod(struct lp_build_sample_context *bld,
+lp_build_brilinear_lod(struct lp_build_context *bld,
LLVMValueRef lod,
double factor,
LLVMValueRef *out_lod_ipart,
LLVMValueRef *out_lod_fpart)
{
- struct lp_build_context *float_bld = &bld->float_bld;
LLVMValueRef lod_fpart;
- float pre_offset = (factor - 0.5)/factor - 0.5;
- float post_offset = 1 - factor;
+ double pre_offset = (factor - 0.5)/factor - 0.5;
+ double post_offset = 1 - factor;
if (0) {
lp_build_printf(bld->builder, "lod = %f\n", lod);
}
- lod = lp_build_add(float_bld, lod,
- lp_build_const_vec(float_bld->type, pre_offset));
+ lod = lp_build_add(bld, lod,
+ lp_build_const_vec(bld->type, pre_offset));
- lp_build_ifloor_fract(float_bld, lod, out_lod_ipart, &lod_fpart);
+ lp_build_ifloor_fract(bld, lod, out_lod_ipart, &lod_fpart);
- lod_fpart = lp_build_mul(float_bld, lod_fpart,
- lp_build_const_vec(float_bld->type, factor));
+ lod_fpart = lp_build_mul(bld, lod_fpart,
+ lp_build_const_vec(bld->type, factor));
- lod_fpart = lp_build_add(float_bld, lod_fpart,
- lp_build_const_vec(float_bld->type, post_offset));
+ lod_fpart = lp_build_add(bld, lod_fpart,
+ lp_build_const_vec(bld->type, post_offset));
/*
* It's not necessary to clamp lod_fpart since:
@@ -335,6 +334,61 @@ lp_build_brilinear_lod(struct lp_build_sample_context *bld,
}
+/*
+ * Combined log2 and brilinear lod computation.
+ *
+ * It's in all identical to calling lp_build_fast_log2() and
+ * lp_build_brilinear_lod() above, but by combining we can compute the interger
+ * and fractional part independently.
+ */
+static void
+lp_build_brilinear_rho(struct lp_build_context *bld,
+ LLVMValueRef rho,
+ double factor,
+ LLVMValueRef *out_lod_ipart,
+ LLVMValueRef *out_lod_fpart)
+{
+ LLVMValueRef lod_ipart;
+ LLVMValueRef lod_fpart;
+
+ const double pre_factor = (2*factor - 0.5)/(M_SQRT2*factor);
+ const double post_offset = 1 - 2*factor;
+
+ assert(bld->type.floating);
+
+ assert(lp_check_value(bld->type, rho));
+
+ /*
+ * The pre factor will make the intersections with the exact powers of two
+ * happen precisely where we want then to be, which means that the integer
+ * part will not need any post adjustments.
+ */
+ rho = lp_build_mul(bld, rho,
+ lp_build_const_vec(bld->type, pre_factor));
+
+ /* ipart = ifloor(log2(rho)) */
+ lod_ipart = lp_build_extract_exponent(bld, rho, 0);
+
+ /* fpart = rho / 2**ipart */
+ lod_fpart = lp_build_extract_mantissa(bld, rho);
+
+ lod_fpart = lp_build_mul(bld, lod_fpart,
+ lp_build_const_vec(bld->type, factor));
+
+ lod_fpart = lp_build_add(bld, lod_fpart,
+ lp_build_const_vec(bld->type, post_offset));
+
+ /*
+ * Like lp_build_brilinear_lod, it's not necessary to clamp lod_fpart since:
+ * - the above expression will never produce numbers greater than one.
+ * - the mip filtering branch is only taken if lod_fpart is positive
+ */
+
+ *out_lod_ipart = lod_ipart;
+ *out_lod_fpart = lod_fpart;
+}
+
+
/**
* Generate code to compute texture level of detail (lambda).
* \param ddx partial derivatives of (s, t, r, q) with respect to X
@@ -389,16 +443,32 @@ lp_build_lod_selector(struct lp_build_sample_context *bld,
rho = lp_build_rho(bld, ddx, ddy);
- /* compute lod = log2(rho) */
- if ((mip_filter == PIPE_TEX_MIPFILTER_NONE ||
- mip_filter == PIPE_TEX_MIPFILTER_NEAREST) &&
- !lod_bias &&
+ /*
+ * Compute lod = log2(rho)
+ */
+
+ if (!lod_bias &&
!bld->static_state->lod_bias_non_zero &&
!bld->static_state->apply_max_lod &&
!bld->static_state->apply_min_lod) {
- *out_lod_ipart = lp_build_ilog2(float_bld, rho);
- *out_lod_fpart = bld->float_bld.zero;
- return;
+ /*
+ * Special case when there are no post-log2 adjustments, which
+ * saves instructions but keeping the integer and fractional lod
+ * computations separate from the start.
+ */
+
+ if (mip_filter == PIPE_TEX_MIPFILTER_NONE ||
+ mip_filter == PIPE_TEX_MIPFILTER_NEAREST) {
+ *out_lod_ipart = lp_build_ilog2(float_bld, rho);
+ *out_lod_fpart = bld->float_bld.zero;
+ return;
+ }
+ if (mip_filter == PIPE_TEX_MIPFILTER_LINEAR &&
+ BRILINEAR_FACTOR > 1.0) {
+ lp_build_brilinear_rho(float_bld, rho, BRILINEAR_FACTOR,
+ out_lod_ipart, out_lod_fpart);
+ return;
+ }
}
if (0) {
@@ -438,20 +508,21 @@ lp_build_lod_selector(struct lp_build_sample_context *bld,
if (mip_filter == PIPE_TEX_MIPFILTER_LINEAR) {
if (BRILINEAR_FACTOR > 1.0) {
- lp_build_brilinear_lod(bld, lod, BRILINEAR_FACTOR,
+ lp_build_brilinear_lod(float_bld, lod, BRILINEAR_FACTOR,
out_lod_ipart, out_lod_fpart);
}
else {
lp_build_ifloor_fract(float_bld, lod, out_lod_ipart, out_lod_fpart);
}
- lp_build_name(*out_lod_ipart, "lod_ipart");
lp_build_name(*out_lod_fpart, "lod_fpart");
}
else {
*out_lod_ipart = lp_build_iround(float_bld, lod);
}
+ lp_build_name(*out_lod_ipart, "lod_ipart");
+
return;
}
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