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-rw-r--r--src/amd/common/ac_llvm_cull.c275
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diff --git a/src/amd/common/ac_llvm_cull.c b/src/amd/common/ac_llvm_cull.c
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-/*
- * Copyright 2019 Advanced Micro Devices, Inc.
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sub license, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
- * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
- * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
- * USE OR OTHER DEALINGS IN THE SOFTWARE.
- *
- * The above copyright notice and this permission notice (including the
- * next paragraph) shall be included in all copies or substantial portions
- * of the Software.
- *
- */
-
-#include "ac_llvm_cull.h"
-#include <llvm-c/Core.h>
-
-struct ac_position_w_info {
- /* If a primitive intersects the W=0 plane, it causes a reflection
- * of the determinant used for face culling. Every vertex behind
- * the W=0 plane negates the determinant, so having 2 vertices behind
- * the plane has no effect. This is i1 true if the determinant should be
- * negated.
- */
- LLVMValueRef w_reflection;
-
- /* If we simplify the "-w <= p <= w" view culling equation, we get
- * "-w <= w", which can't be satisfied when w is negative.
- * In perspective projection, a negative W means that the primitive
- * is behind the viewer, but the equation is independent of the type
- * of projection.
- *
- * w_accepted is false when all W are negative and therefore
- * the primitive is invisible.
- */
- LLVMValueRef w_accepted;
-
- LLVMValueRef all_w_positive;
- LLVMValueRef any_w_negative;
-};
-
-static void ac_analyze_position_w(struct ac_llvm_context *ctx,
- LLVMValueRef pos[3][4],
- struct ac_position_w_info *w)
-{
- LLVMBuilderRef builder = ctx->builder;
- LLVMValueRef all_w_negative = ctx->i1true;
-
- w->w_reflection = ctx->i1false;
- w->any_w_negative = ctx->i1false;
-
- for (unsigned i = 0; i < 3; i++) {
- LLVMValueRef neg_w;
-
- neg_w = LLVMBuildFCmp(builder, LLVMRealOLT, pos[i][3], ctx->f32_0, "");
- /* If neg_w is true, negate w_reflection. */
- w->w_reflection = LLVMBuildXor(builder, w->w_reflection, neg_w, "");
- w->any_w_negative = LLVMBuildOr(builder, w->any_w_negative, neg_w, "");
- all_w_negative = LLVMBuildAnd(builder, all_w_negative, neg_w, "");
- }
- w->all_w_positive = LLVMBuildNot(builder, w->any_w_negative, "");
- w->w_accepted = LLVMBuildNot(builder, all_w_negative, "");
-}
-
-/* Perform front/back face culling and return true if the primitive is accepted. */
-static LLVMValueRef ac_cull_face(struct ac_llvm_context *ctx,
- LLVMValueRef pos[3][4],
- struct ac_position_w_info *w,
- bool cull_front,
- bool cull_back,
- bool cull_zero_area)
-{
- LLVMBuilderRef builder = ctx->builder;
-
- if (cull_front && cull_back)
- return ctx->i1false;
-
- if (!cull_front && !cull_back && !cull_zero_area)
- return ctx->i1true;
-
- /* Front/back face culling. Also if the determinant == 0, the triangle
- * area is 0.
- */
- LLVMValueRef det_t0 = LLVMBuildFSub(builder, pos[2][0], pos[0][0], "");
- LLVMValueRef det_t1 = LLVMBuildFSub(builder, pos[1][1], pos[0][1], "");
- LLVMValueRef det_t2 = LLVMBuildFSub(builder, pos[0][0], pos[1][0], "");
- LLVMValueRef det_t3 = LLVMBuildFSub(builder, pos[0][1], pos[2][1], "");
- LLVMValueRef det_p0 = LLVMBuildFMul(builder, det_t0, det_t1, "");
- LLVMValueRef det_p1 = LLVMBuildFMul(builder, det_t2, det_t3, "");
- LLVMValueRef det = LLVMBuildFSub(builder, det_p0, det_p1, "");
-
- /* Negative W negates the determinant. */
- det = LLVMBuildSelect(builder, w->w_reflection,
- LLVMBuildFNeg(builder, det, ""),
- det, "");
-
- LLVMValueRef accepted = NULL;
- if (cull_front) {
- LLVMRealPredicate cond = cull_zero_area ? LLVMRealOGT : LLVMRealOGE;
- accepted = LLVMBuildFCmp(builder, cond, det, ctx->f32_0, "");
- } else if (cull_back) {
- LLVMRealPredicate cond = cull_zero_area ? LLVMRealOLT : LLVMRealOLE;
- accepted = LLVMBuildFCmp(builder, cond, det, ctx->f32_0, "");
- } else if (cull_zero_area) {
- accepted = LLVMBuildFCmp(builder, LLVMRealONE, det, ctx->f32_0, "");
- }
- return accepted;
-}
-
-/* Perform view culling and small primitive elimination and return true
- * if the primitive is accepted and initially_accepted == true. */
-static LLVMValueRef cull_bbox(struct ac_llvm_context *ctx,
- LLVMValueRef pos[3][4],
- LLVMValueRef initially_accepted,
- struct ac_position_w_info *w,
- LLVMValueRef vp_scale[2],
- LLVMValueRef vp_translate[2],
- LLVMValueRef small_prim_precision,
- bool cull_view_xy,
- bool cull_view_near_z,
- bool cull_view_far_z,
- bool cull_small_prims,
- bool use_halfz_clip_space)
-{
- LLVMBuilderRef builder = ctx->builder;
-
- if (!cull_view_xy && !cull_view_near_z && !cull_view_far_z && !cull_small_prims)
- return ctx->i1true;
-
- /* Skip the culling if the primitive has already been rejected or
- * if any W is negative. The bounding box culling doesn't work when
- * W is negative.
- */
- LLVMValueRef cond = LLVMBuildAnd(builder, initially_accepted,
- w->all_w_positive, "");
- LLVMValueRef accepted_var = ac_build_alloca_undef(ctx, ctx->i1, "");
- LLVMBuildStore(builder, initially_accepted, accepted_var);
-
- ac_build_ifcc(ctx, cond, 10000000 /* does this matter? */);
- {
- LLVMValueRef bbox_min[3], bbox_max[3];
- LLVMValueRef accepted = initially_accepted;
-
- /* Compute the primitive bounding box for easy culling. */
- for (unsigned chan = 0; chan < 3; chan++) {
- bbox_min[chan] = ac_build_fmin(ctx, pos[0][chan], pos[1][chan]);
- bbox_min[chan] = ac_build_fmin(ctx, bbox_min[chan], pos[2][chan]);
-
- bbox_max[chan] = ac_build_fmax(ctx, pos[0][chan], pos[1][chan]);
- bbox_max[chan] = ac_build_fmax(ctx, bbox_max[chan], pos[2][chan]);
- }
-
- /* View culling. */
- if (cull_view_xy || cull_view_near_z || cull_view_far_z) {
- for (unsigned chan = 0; chan < 3; chan++) {
- LLVMValueRef visible;
-
- if ((cull_view_xy && chan <= 1) ||
- (cull_view_near_z && chan == 2)) {
- float t = chan == 2 && use_halfz_clip_space ? 0 : -1;
- visible = LLVMBuildFCmp(builder, LLVMRealOGE, bbox_max[chan],
- LLVMConstReal(ctx->f32, t), "");
- accepted = LLVMBuildAnd(builder, accepted, visible, "");
- }
-
- if ((cull_view_xy && chan <= 1) ||
- (cull_view_far_z && chan == 2)) {
- visible = LLVMBuildFCmp(builder, LLVMRealOLE, bbox_min[chan],
- ctx->f32_1, "");
- accepted = LLVMBuildAnd(builder, accepted, visible, "");
- }
- }
- }
-
- /* Small primitive elimination. */
- if (cull_small_prims) {
- /* Assuming a sample position at (0.5, 0.5), if we round
- * the bounding box min/max extents and the results of
- * the rounding are equal in either the X or Y direction,
- * the bounding box does not intersect the sample.
- *
- * See these GDC slides for pictures:
- * https://frostbite-wp-prd.s3.amazonaws.com/wp-content/uploads/2016/03/29204330/GDC_2016_Compute.pdf
- */
- LLVMValueRef min, max, not_equal[2], visible;
-
- for (unsigned chan = 0; chan < 2; chan++) {
- /* Convert the position to screen-space coordinates. */
- min = ac_build_fmad(ctx, bbox_min[chan],
- vp_scale[chan], vp_translate[chan]);
- max = ac_build_fmad(ctx, bbox_max[chan],
- vp_scale[chan], vp_translate[chan]);
- /* Scale the bounding box according to the precision of
- * the rasterizer and the number of MSAA samples. */
- min = LLVMBuildFSub(builder, min, small_prim_precision, "");
- max = LLVMBuildFAdd(builder, max, small_prim_precision, "");
-
- /* Determine if the bbox intersects the sample point.
- * It also works for MSAA, but vp_scale, vp_translate,
- * and small_prim_precision are computed differently.
- */
- min = ac_build_round(ctx, min);
- max = ac_build_round(ctx, max);
- not_equal[chan] = LLVMBuildFCmp(builder, LLVMRealONE, min, max, "");
- }
- visible = LLVMBuildAnd(builder, not_equal[0], not_equal[1], "");
- accepted = LLVMBuildAnd(builder, accepted, visible, "");
- }
-
- LLVMBuildStore(builder, accepted, accepted_var);
- }
- ac_build_endif(ctx, 10000000);
-
- return LLVMBuildLoad(builder, accepted_var, "");
-}
-
-/**
- * Return i1 true if the primitive is accepted (not culled).
- *
- * \param pos Vertex positions 3x vec4
- * \param initially_accepted AND'ed with the result. Some computations can be
- * skipped if this is false.
- * \param vp_scale Viewport scale XY.
- * For MSAA, multiply them by the number of samples.
- * \param vp_translate Viewport translation XY.
- * For MSAA, multiply them by the number of samples.
- * \param small_prim_precision Precision of small primitive culling. This should
- * be the same as or greater than the precision of
- * the rasterizer. Set to num_samples / 2^subpixel_bits.
- * subpixel_bits are defined by the quantization mode.
- * \param options See ac_cull_options.
- */
-LLVMValueRef ac_cull_triangle(struct ac_llvm_context *ctx,
- LLVMValueRef pos[3][4],
- LLVMValueRef initially_accepted,
- LLVMValueRef vp_scale[2],
- LLVMValueRef vp_translate[2],
- LLVMValueRef small_prim_precision,
- struct ac_cull_options *options)
-{
- struct ac_position_w_info w;
- ac_analyze_position_w(ctx, pos, &w);
-
- /* W culling. */
- LLVMValueRef accepted = options->cull_w ? w.w_accepted : ctx->i1true;
- accepted = LLVMBuildAnd(ctx->builder, accepted, initially_accepted, "");
-
- /* Face culling. */
- accepted = LLVMBuildAnd(ctx->builder, accepted,
- ac_cull_face(ctx, pos, &w,
- options->cull_front,
- options->cull_back,
- options->cull_zero_area), "");
-
- /* View culling and small primitive elimination. */
- accepted = cull_bbox(ctx, pos, accepted, &w, vp_scale, vp_translate,
- small_prim_precision,
- options->cull_view_xy,
- options->cull_view_near_z,
- options->cull_view_far_z,
- options->cull_small_prims,
- options->use_halfz_clip_space);
- return accepted;
-}
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