[Mesa-dev] [PATCH 09/11] nir: add lowering stage for user-clip-planes / clipdist
Rob Clark
robdclark at gmail.com
Sun Sep 13 08:51:56 PDT 2015
From: Rob Clark <robclark at freedesktop.org>
The vertex shader lowering adds calculation for CLIPDIST, if needed
(ie. user-clip-planes), and the frag shader lowering adds conditional
kills based on CLIPDIST value (which should be treated as a normal
interpolated varying by the driver).
Signed-off-by: Rob Clark <robclark at freedesktop.org>
---
src/glsl/Makefile.sources | 1 +
src/glsl/nir/nir.h | 3 +
src/glsl/nir/nir_lower_clip.c | 341 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 345 insertions(+)
create mode 100644 src/glsl/nir/nir_lower_clip.c
diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
index da7fdf9..5d98b7b 100644
--- a/src/glsl/Makefile.sources
+++ b/src/glsl/Makefile.sources
@@ -35,6 +35,7 @@ NIR_FILES = \
nir/nir_live_variables.c \
nir/nir_lower_alu_to_scalar.c \
nir/nir_lower_atomics.c \
+ nir/nir_lower_clip.c \
nir/nir_lower_global_vars_to_local.c \
nir/nir_lower_load_const_to_scalar.c \
nir/nir_lower_locals_to_regs.c \
diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
index 3f693b1..1e91ab5 100644
--- a/src/glsl/nir/nir.h
+++ b/src/glsl/nir/nir.h
@@ -1824,6 +1824,9 @@ void nir_lower_system_values(nir_shader *shader);
void nir_lower_tex_projector(nir_shader *shader);
void nir_lower_idiv(nir_shader *shader);
+void nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables);
+void nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables);
+
void nir_lower_atomics(nir_shader *shader);
void nir_lower_to_source_mods(nir_shader *shader);
diff --git a/src/glsl/nir/nir_lower_clip.c b/src/glsl/nir/nir_lower_clip.c
new file mode 100644
index 0000000..b278aa2
--- /dev/null
+++ b/src/glsl/nir/nir_lower_clip.c
@@ -0,0 +1,341 @@
+/*
+ * Copyright © 2015 Red Hat
+ *
+ * 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, sublicense,
+ * 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 above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * 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 NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ *
+ * Authors:
+ * Rob Clark <robclark at freedesktop.org>
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+
+#define MAX_CLIP_PLANES 8
+
+/* Generates the lowering code for user-clip-planes, generating CLIPDIST
+ * from UCP[n] + CLIPVERTEX or POSITION. Additionally, an optional pass
+ * for fragment shaders to insert conditional kill's based on the inter-
+ * polated CLIPDIST
+ *
+ * NOTE: should be run after nir_lower_outputs_to_temporaries() (or at
+ * least in scenarios where you can count on each output written once
+ * and only once).
+ */
+
+
+static nir_variable *
+create_clipdist_var(nir_shader *shader, unsigned drvloc,
+ bool output, gl_varying_slot slot)
+{
+ nir_variable *var = rzalloc(shader, nir_variable);
+
+ var->data.driver_location = drvloc;
+ var->type = glsl_vec4_type();
+ var->data.mode = output ? nir_var_shader_out : nir_var_shader_in;
+ var->name = ralloc_asprintf(var, "clipdist_%d", drvloc);
+ var->data.index = 0;
+ var->data.location = slot;
+
+ if (output) {
+ exec_list_push_tail(&shader->outputs, &var->node);
+ }
+ else {
+ exec_list_push_tail(&shader->inputs, &var->node);
+ }
+ return var;
+}
+
+static void
+store_clipdist_output(nir_builder *b, nir_variable *out, nir_ssa_def **val)
+{
+ nir_intrinsic_instr *store;
+
+ store = nir_intrinsic_instr_create(b->shader, nir_intrinsic_store_output);
+ store->num_components = 4;
+ store->const_index[0] = out->data.driver_location;
+ store->src[0].ssa = nir_vec4(b, val[0], val[1], val[2], val[3]);
+ store->src[0].is_ssa = true;
+ nir_builder_instr_insert(b, &store->instr);
+}
+
+static void
+load_clipdist_input(nir_builder *b, nir_variable *in, nir_ssa_def **val)
+{
+ nir_intrinsic_instr *load;
+
+ load = nir_intrinsic_instr_create(b->shader, nir_intrinsic_load_input);
+ load->num_components = 4;
+ load->const_index[0] = in->data.driver_location;
+ nir_ssa_dest_init(&load->instr, &load->dest, 4, NULL);
+ nir_builder_instr_insert(b, &load->instr);
+
+ val[0] = nir_channel(b, &load->dest.ssa, 0);
+ val[1] = nir_channel(b, &load->dest.ssa, 1);
+ val[2] = nir_channel(b, &load->dest.ssa, 2);
+ val[3] = nir_channel(b, &load->dest.ssa, 3);
+}
+
+struct find_output_state
+{
+ unsigned drvloc;
+ nir_ssa_def *def;
+};
+
+static bool
+find_output_in_block(nir_block *block, void *void_state)
+{
+ struct find_output_state *state = void_state;
+ nir_foreach_instr(block, instr) {
+
+ if (instr->type == nir_instr_type_intrinsic) {
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if ((intr->intrinsic == nir_intrinsic_store_output) &&
+ intr->const_index[0] == state->drvloc) {
+ assert(state->def == NULL);
+ assert(intr->src[0].is_ssa);
+ state->def = intr->src[0].ssa;
+ }
+ }
+
+#if !defined(DEBUG)
+ /* for debug builds, scan entire shader to assert
+ * if output is written multiple times. For release
+ * builds just assume all is well and bail when we
+ * find first:
+ */
+ if (state->def)
+ return false;
+#endif
+ }
+
+ return true;
+}
+
+/* TODO: maybe this would be a useful helper?
+ * NOTE: assumes each output is written exactly once (and unconditionally)
+ * so if needed nir_lower_outputs_to_temporaries()
+ */
+static nir_ssa_def *
+find_output(nir_shader *shader, unsigned drvloc)
+{
+ struct find_output_state state = {
+ .drvloc = drvloc,
+ };
+
+ nir_foreach_overload(shader, overload) {
+ if (overload->impl) {
+ nir_foreach_block_reverse(overload->impl,
+ find_output_in_block, &state);
+ }
+ }
+
+ return state.def;
+}
+
+/*
+ * VS lowering
+ */
+
+static void
+lower_clip_vs(nir_function_impl *impl, unsigned ucp_enables,
+ nir_ssa_def *cv, nir_variable **out)
+{
+ nir_ssa_def *clipdist[MAX_CLIP_PLANES];
+ nir_builder b;
+
+ nir_builder_init(&b, impl);
+
+ /* NIR should ensure that, even in case of loops/if-else, there
+ * should be only a single predecessor block to end_block, which
+ * makes the perfect place to insert the clipdist calculations.
+ *
+ * NOTE: in case of early return's, these would have to be lowered
+ * to jumps to end_block predecessor in a previous pass. Not sure
+ * if there is a good way to sanity check this, but for now the
+ * users of this pass don't support sub-routines.
+ */
+ assert(impl->end_block->predecessors->entries == 1);
+ b.cursor = nir_after_cf_list(&impl->body);
+
+ for (int plane = 0; plane < MAX_CLIP_PLANES; plane++) {
+ if (ucp_enables & (1 << plane)) {
+ nir_intrinsic_instr *ucp;
+
+ /* insert intrinsic to fetch ucp[plane]: */
+ ucp = nir_intrinsic_instr_create(b.shader,
+ nir_intrinsic_load_user_clip_plane);
+ ucp->num_components = 4;
+ ucp->const_index[0] = plane;
+ nir_ssa_dest_init(&ucp->instr, &ucp->dest, 4, NULL);
+ nir_builder_instr_insert(&b, &ucp->instr);
+
+ /* calculate clipdist[plane] - dot(ucp, cv): */
+ clipdist[plane] = nir_fdot4(&b, &ucp->dest.ssa, cv);
+ }
+ else {
+ /* 0.0 == don't-clip == disabled: */
+ clipdist[plane] = nir_imm_float(&b, 0.0);
+ }
+ }
+
+ if (ucp_enables & 0x0f)
+ store_clipdist_output(&b, out[0], &clipdist[0]);
+ if (ucp_enables & 0xf0)
+ store_clipdist_output(&b, out[1], &clipdist[4]);
+
+ nir_metadata_preserve(impl, nir_metadata_dominance);
+}
+
+/* ucp_enables is bitmask of enabled ucp's. Actual ucp values are
+ * passed in to shader via user_clip_plane system-values
+ */
+void
+nir_lower_clip_vs(nir_shader *shader, unsigned ucp_enables)
+{
+ int clipvertex = -1;
+ int position = -1;
+ int maxloc = -1;
+ nir_ssa_def *cv;
+ nir_variable *out[2];
+
+ if (!ucp_enables)
+ return;
+
+ /* find clipvertex/position outputs: */
+ foreach_list_typed(nir_variable, var, node, &shader->outputs) {
+ int loc = var->data.driver_location;
+
+ /* keep track of last used driver-location.. we'll be
+ * appending CLIP_DIST0/CLIP_DIST1 after last existing
+ * output:
+ */
+ maxloc = MAX2(maxloc, loc);
+
+ switch (var->data.location) {
+ case VARYING_SLOT_POS:
+ position = loc;
+ break;
+ case VARYING_SLOT_CLIP_VERTEX:
+ clipvertex = loc;
+ break;
+ case VARYING_SLOT_CLIP_DIST0:
+ case VARYING_SLOT_CLIP_DIST1:
+ /* if shader is already writing CLIPDIST, then
+ * there should be no user-clip-planes to deal
+ * with.
+ */
+ return;
+ }
+ }
+
+ if (clipvertex != -1)
+ cv = find_output(shader, clipvertex);
+ else if (position != -1)
+ cv = find_output(shader, position);
+ else
+ return;
+
+ /* insert CLIPDIST outputs: */
+ if (ucp_enables & 0x0f)
+ out[0] =
+ create_clipdist_var(shader, ++maxloc, true, VARYING_SLOT_CLIP_DIST0);
+ if (ucp_enables & 0xf0)
+ out[1] =
+ create_clipdist_var(shader, ++maxloc, true, VARYING_SLOT_CLIP_DIST1);
+
+ nir_foreach_overload(shader, overload) {
+ if (!strcmp(overload->function->name, "main"))
+ lower_clip_vs(overload->impl, ucp_enables, cv, out);
+ }
+}
+
+/*
+ * FS lowering
+ */
+
+static void
+lower_clip_fs(nir_function_impl *impl, unsigned ucp_enables,
+ nir_variable **in)
+{
+ nir_ssa_def *clipdist[MAX_CLIP_PLANES];
+ nir_builder b;
+
+ nir_builder_init(&b, impl);
+ b.cursor = nir_before_cf_list(&impl->body);
+
+ if (ucp_enables & 0x0f)
+ load_clipdist_input(&b, in[0], &clipdist[0]);
+ if (ucp_enables & 0xf0)
+ load_clipdist_input(&b, in[1], &clipdist[4]);
+
+ for (int plane = 0; plane < MAX_CLIP_PLANES; plane++) {
+ if (ucp_enables & (1 << plane)) {
+ nir_intrinsic_instr *discard;
+ nir_ssa_def *cond;
+
+ cond = nir_flt(&b, clipdist[plane], nir_imm_float(&b, 0.0));
+
+ discard = nir_intrinsic_instr_create(b.shader,
+ nir_intrinsic_discard_if);
+ discard->src[0] = nir_src_for_ssa(cond);
+ nir_builder_instr_insert(&b, &discard->instr);
+ }
+ }
+}
+
+/* insert conditional kill based on interpolated CLIPDIST
+ */
+void
+nir_lower_clip_fs(nir_shader *shader, unsigned ucp_enables)
+{
+ nir_variable *in[2];
+ int maxloc = -1;
+
+ if (!ucp_enables)
+ return;
+
+ foreach_list_typed(nir_variable, var, node, &shader->inputs) {
+ int loc = var->data.driver_location;
+
+ /* keep track of last used driver-location.. we'll be
+ * appending CLIP_DIST0/CLIP_DIST1 after last existing
+ * input:
+ */
+ maxloc = MAX2(maxloc, loc);
+ }
+
+ /* The shader won't normally have CLIPDIST inputs, so we
+ * must add our own:
+ */
+ /* insert CLIPDIST outputs: */
+ if (ucp_enables & 0x0f)
+ in[0] =
+ create_clipdist_var(shader, ++maxloc, false,
+ VARYING_SLOT_CLIP_DIST0);
+ if (ucp_enables & 0xf0)
+ in[1] =
+ create_clipdist_var(shader, ++maxloc, false,
+ VARYING_SLOT_CLIP_DIST1);
+
+ nir_foreach_overload(shader, overload) {
+ if (!strcmp(overload->function->name, "main"))
+ lower_clip_fs(overload->impl, ucp_enables, in);
+ }
+}
--
2.4.3
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