NIR_PASS_V(nir, nir_lower_vars_to_ssa);
NIR_PASS_V(nir, nir_lower_io, nir_var_shader_in | nir_var_shader_out,
glsl_type_size, 0);
+ NIR_PASS_V(nir, nir_lower_ssbo);
if (nir->info.stage == MESA_SHADER_FRAGMENT) {
+ NIR_PASS_V(nir, agx_nir_lower_frag_sidefx);
NIR_PASS_V(nir, agx_nir_lower_zs_emit);
/* Interpolate varyings at fp16 and write to the tilebuffer at fp16. As an
NIR_PASS_V(nir, nir_opt_move, move_all);
NIR_PASS_V(nir, agx_nir_lower_ubo);
NIR_PASS_V(nir, agx_nir_lower_shared_bitsize);
- NIR_PASS_V(nir, nir_lower_ssbo);
}
void
--- /dev/null
+/*
+ * Copyright 2022 Alyssa Rosenzweig
+ * SPDX-License-Identifier: MIT
+ */
+
+#include "compiler/nir/nir.h"
+#include "compiler/nir/nir_builder.h"
+#include "agx_compiler.h"
+
+/* Fragment shaders with side effects require special handling to ensure the
+ * side effects execute as intended. By default, they require late depth
+ * testing, to ensure the side effects happen even for killed pixels. To handle,
+ * the driver inserts a dummy `gl_FragDepth = gl_Position.z` in shaders that
+ * don't otherwise write their depth, forcing a late depth test.
+ *
+ * For side effects with force early testing forced, the sample mask is written
+ * at the *beginning* of the shader (TODO: handle).
+ */
+
+static bool
+pass(struct nir_builder *b, nir_instr *instr, void *data)
+{
+ if (instr->type != nir_instr_type_intrinsic)
+ return false;
+
+ nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
+ if (intr->intrinsic != nir_intrinsic_store_output)
+ return false;
+
+ /* Only lower once */
+ bool *done = data;
+ if (*done)
+ return false;
+ *done = true;
+
+ b->cursor = nir_before_instr(instr);
+ nir_ssa_def *zero = nir_imm_int(b, 0);
+ nir_ssa_def *pixel = nir_load_barycentric_pixel(b, 32, .interp_mode = 1);
+
+ nir_ssa_def *position =
+ nir_load_interpolated_input(b, 1, 32, pixel, zero, .component = 2 /* Z */,
+ .dest_type = nir_type_float32,
+ .io_semantics = {
+ .location = VARYING_SLOT_POS,
+ .num_slots = 1,
+ });
+
+ nir_store_output(b, position, zero,
+ .io_semantics.location = FRAG_RESULT_DEPTH,
+ .write_mask = BITFIELD_MASK(1),
+ .src_type = nir_type_float32);
+
+ b->shader->info.inputs_read |= BITFIELD64_BIT(VARYING_SLOT_POS);
+ b->shader->info.outputs_written |= BITFIELD64_BIT(FRAG_RESULT_DEPTH);
+ return true;
+}
+
+bool
+agx_nir_lower_frag_sidefx(nir_shader *s)
+{
+ assert(s->info.stage == MESA_SHADER_FRAGMENT);
+
+ /* If there are no side effects, there's nothing to lower */
+ if (!s->info.writes_memory)
+ return false;
+
+ /* Lower writes from helper invocations with the common pass */
+ NIR_PASS_V(s, nir_lower_helper_writes, false);
+
+ /* If depth/stencil feedback is already used, we're done */
+ if (s->info.outputs_written & (BITFIELD64_BIT(FRAG_RESULT_STENCIL) |
+ BITFIELD64_BIT(FRAG_RESULT_DEPTH)))
+ return false;
+
+ bool done = false;
+ return nir_shader_instructions_pass(
+ s, pass, nir_metadata_block_index | nir_metadata_dominance, &done);
+}