--- /dev/null
+/*
+ * 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.
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+
+/* Lower gl_FragCoord (and fddy) to account for driver's requested coordinate-
+ * origin and pixel-center vs. shader. If transformation is required, a
+ * gl_FbWposYTransform uniform is inserted (with the specified state-slots)
+ * and additional instructions are inserted to transform gl_FragCoord (and
+ * fddy src arg).
+ *
+ * This is based on the logic in emit_wpos()/emit_wpos_adjustment() in TGSI
+ * compiler.
+ *
+ * Run before nir_lower_io.
+ */
+
+typedef struct {
+ const nir_lower_wpos_ytransform_options *options;
+ nir_shader *shader;
+ nir_builder b;
+ nir_variable *transform;
+} lower_wpos_ytransform_state;
+
+static nir_ssa_def *
+get_transform(lower_wpos_ytransform_state *state)
+{
+ if (state->transform == NULL) {
+ /* NOTE: name must be prefixed w/ "gl_" to trigger slot based
+ * special handling in uniform setup:
+ */
+ nir_variable *var = nir_variable_create(state->shader,
+ nir_var_uniform,
+ glsl_vec4_type(),
+ "gl_FbWposYTransform");
+
+ var->num_state_slots = 1;
+ var->state_slots = ralloc_array(var, nir_state_slot, 1);
+ memcpy(var->state_slots[0].tokens, state->options->state_tokens,
+ sizeof(var->state_slots[0].tokens));
+
+ state->transform = var;
+ }
+ return nir_load_var(&state->b, state->transform);
+}
+
+/* NIR equiv of TGSI CMP instruction: */
+static nir_ssa_def *
+nir_cmp(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1, nir_ssa_def *src2)
+{
+ return nir_bcsel(b, nir_flt(b, src0, nir_imm_float(b, 0.0)), src1, src2);
+}
+
+/* see emit_wpos_adjustment() in st_mesa_to_tgsi.c */
+static void
+emit_wpos_adjustment(lower_wpos_ytransform_state *state,
+ nir_intrinsic_instr *intr,
+ bool invert, float adjX, float adjY[2])
+{
+ nir_builder *b = &state->b;
+ nir_variable *fragcoord = intr->variables[0]->var;
+ nir_ssa_def *wpostrans, *wpos_temp, *wpos_temp_y, *wpos_input;
+
+ assert(intr->dest.is_ssa);
+
+ b->cursor = nir_before_instr(&intr->instr);
+
+ wpostrans = get_transform(state);
+ wpos_input = nir_load_var(b, fragcoord);
+
+ /* First, apply the coordinate shift: */
+ if (adjX || adjY[0] || adjY[1]) {
+ if (adjY[0] != adjY[1]) {
+ /* Adjust the y coordinate by adjY[1] or adjY[0] respectively
+ * depending on whether inversion is actually going to be applied
+ * or not, which is determined by testing against the inversion
+ * state variable used below, which will be either +1 or -1.
+ */
+ nir_ssa_def *adj_temp;
+
+ adj_temp = nir_cmp(b,
+ nir_channel(b, wpostrans, invert ? 2 : 0),
+ nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f),
+ nir_imm_vec4(b, adjX, adjY[1], 0.0f, 0.0f));
+
+ wpos_temp = nir_fadd(b, wpos_input, adj_temp);
+ } else {
+ wpos_temp = nir_fadd(b,
+ wpos_input,
+ nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f));
+ }
+ wpos_input = wpos_temp;
+ } else {
+ /* MOV wpos_temp, input[wpos]
+ */
+ wpos_temp = wpos_input;
+ }
+
+ /* Now the conditional y flip: STATE_FB_WPOS_Y_TRANSFORM.xy/zw will be
+ * inversion/identity, or the other way around if we're drawing to an FBO.
+ */
+ if (invert) {
+ /* MAD wpos_temp.y, wpos_input, wpostrans.xxxx, wpostrans.yyyy
+ */
+ wpos_temp_y = nir_ffma(b,
+ nir_channel(b, wpos_temp, 1),
+ nir_channel(b, wpostrans, 0),
+ nir_channel(b, wpostrans, 1));
+ } else {
+ /* MAD wpos_temp.y, wpos_input, wpostrans.zzzz, wpostrans.wwww
+ */
+ wpos_temp_y = nir_ffma(b,
+ nir_channel(b, wpos_temp, 1),
+ nir_channel(b, wpostrans, 2),
+ nir_channel(b, wpostrans, 3));
+ }
+
+ wpos_temp = nir_vec4(b,
+ nir_channel(b, wpos_temp, 0),
+ wpos_temp_y,
+ nir_channel(b, wpos_temp, 2),
+ nir_channel(b, wpos_temp, 3));
+
+ nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(wpos_temp));
+}
+
+static void
+lower_fragcoord(lower_wpos_ytransform_state *state, nir_intrinsic_instr *intr)
+{
+ const nir_lower_wpos_ytransform_options *options = state->options;
+ nir_variable *fragcoord = intr->variables[0]->var;
+ float adjX = 0.0f;
+ float adjY[2] = { 0.0f, 0.0f };
+ bool invert = false;
+
+ /* Based on logic in emit_wpos():
+ *
+ * Query the pixel center conventions supported by the pipe driver and set
+ * adjX, adjY to help out if it cannot handle the requested one internally.
+ *
+ * The bias of the y-coordinate depends on whether y-inversion takes place
+ * (adjY[1]) or not (adjY[0]), which is in turn dependent on whether we are
+ * drawing to an FBO (causes additional inversion), and whether the the pipe
+ * driver origin and the requested origin differ (the latter condition is
+ * stored in the 'invert' variable).
+ *
+ * For height = 100 (i = integer, h = half-integer, l = lower, u = upper):
+ *
+ * center shift only:
+ * i -> h: +0.5
+ * h -> i: -0.5
+ *
+ * inversion only:
+ * l,i -> u,i: ( 0.0 + 1.0) * -1 + 100 = 99
+ * l,h -> u,h: ( 0.5 + 0.0) * -1 + 100 = 99.5
+ * u,i -> l,i: (99.0 + 1.0) * -1 + 100 = 0
+ * u,h -> l,h: (99.5 + 0.0) * -1 + 100 = 0.5
+ *
+ * inversion and center shift:
+ * l,i -> u,h: ( 0.0 + 0.5) * -1 + 100 = 99.5
+ * l,h -> u,i: ( 0.5 + 0.5) * -1 + 100 = 99
+ * u,i -> l,h: (99.0 + 0.5) * -1 + 100 = 0.5
+ * u,h -> l,i: (99.5 + 0.5) * -1 + 100 = 0
+ */
+
+ if (fragcoord->data.origin_upper_left) {
+ /* Fragment shader wants origin in upper-left */
+ if (options->fs_coord_origin_upper_left) {
+ /* the driver supports upper-left origin */
+ } else if (options->fs_coord_origin_lower_left) {
+ /* the driver supports lower-left origin, need to invert Y */
+ invert = true;
+ } else {
+ unreachable("invalid options");
+ }
+ } else {
+ /* Fragment shader wants origin in lower-left */
+ if (options->fs_coord_origin_lower_left) {
+ /* the driver supports lower-left origin */
+ } else if (options->fs_coord_origin_upper_left) {
+ /* the driver supports upper-left origin, need to invert Y */
+ invert = true;
+ } else {
+ unreachable("invalid options");
+ }
+ }
+
+ if (fragcoord->data.pixel_center_integer) {
+ /* Fragment shader wants pixel center integer */
+ if (options->fs_coord_pixel_center_integer) {
+ /* the driver supports pixel center integer */
+ adjY[1] = 1.0f;
+ } else if (options->fs_coord_pixel_center_half_integer) {
+ /* the driver supports pixel center half integer, need to bias X,Y */
+ adjX = -0.5f;
+ adjY[0] = -0.5f;
+ adjY[1] = 0.5f;
+ } else {
+ unreachable("invalid options");
+ }
+ } else {
+ /* Fragment shader wants pixel center half integer */
+ if (options->fs_coord_pixel_center_half_integer) {
+ /* the driver supports pixel center half integer */
+ } else if (options->fs_coord_pixel_center_integer) {
+ /* the driver supports pixel center integer, need to bias X,Y */
+ adjX = adjY[0] = adjY[1] = 0.5f;
+ } else {
+ unreachable("invalid options");
+ }
+ }
+
+ emit_wpos_adjustment(state, intr, invert, adjX, adjY);
+}
+
+/* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */
+static void
+lower_fddy(lower_wpos_ytransform_state *state, nir_alu_instr *fddy)
+{
+ nir_builder *b = &state->b;
+ nir_ssa_def *p, *pt, *trans;
+
+ b->cursor = nir_before_instr(&fddy->instr);
+
+ p = nir_ssa_for_alu_src(b, fddy, 0);
+ trans = get_transform(state);
+ pt = nir_fmul(b, p, nir_channel(b, trans, 0));
+
+ nir_instr_rewrite_src(&fddy->instr,
+ &fddy->src[0].src,
+ nir_src_for_ssa(pt));
+}
+
+static bool
+lower_wpos_ytransform_block(lower_wpos_ytransform_state *state, nir_block *block)
+{
+ nir_foreach_instr_safe(instr, block) {
+ if (instr->type == nir_instr_type_intrinsic) {
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic == nir_intrinsic_load_var) {
+ nir_deref_var *dvar = intr->variables[0];
+ nir_variable *var = dvar->var;
+
+ if (strcmp(var->name, "gl_FragCoord") == 0) {
+ /* gl_FragCoord should not have array/struct deref's: */
+ assert(dvar->deref.child == NULL);
+ lower_fragcoord(state, intr);
+ }
+ }
+ } else if (instr->type == nir_instr_type_alu) {
+ nir_alu_instr *alu = nir_instr_as_alu(instr);
+ if (alu->op == nir_op_fddy)
+ lower_fddy(state, alu);
+ }
+ }
+
+ return true;
+}
+
+static void
+lower_wpos_ytransform_impl(lower_wpos_ytransform_state *state, nir_function_impl *impl)
+{
+ nir_builder_init(&state->b, impl);
+
+ nir_foreach_block(block, impl) {
+ lower_wpos_ytransform_block(state, block);
+ }
+ nir_metadata_preserve(impl, nir_metadata_block_index |
+ nir_metadata_dominance);
+}
+
+bool
+nir_lower_wpos_ytransform(nir_shader *shader,
+ const nir_lower_wpos_ytransform_options *options)
+{
+ lower_wpos_ytransform_state state = {
+ .options = options,
+ .shader = shader,
+ };
+
+ assert(shader->stage == MESA_SHADER_FRAGMENT);
+
+ nir_foreach_function(function, shader) {
+ if (function->impl)
+ lower_wpos_ytransform_impl(&state, function->impl);
+ }
+
+ return state.transform != NULL;
+}
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