[Mesa-dev] [PATCH 19/30] i965/gs: add GS visitors.
Paul Berry
stereotype441 at gmail.com
Tue Aug 20 11:30:34 PDT 2013
This patch introduces the vec4_gs_visitor class, which translates
geometry shaders from GLSL IR to back-end opcodes.
This class is derived from vec4_visitor (which is also the base class
for vec4_vs_visitor), so as a result most of the back end code is
shared. The only parts that differ are:
- Geometry shaders use a different input payload organization, since
the inputs need to match up with the outputs of the previous
pipeline stage (vec4_gs_visitor::setup_payload() and
vec4_gs_visitor::setup_varying_inputs()).
- Geometry shader input array dereferences need a special stride
computation, since all geometry shader inputs are interleaved into
one giant array (vec4_gs_visitor::compute_array_stride()).
- There are no geometry shader system values
(vec4_gs_visitor::make_reg_for_system_value()).
- At the beginning of a geometry shader, extra data in R0 needs to be
zeroed out, and a vertex counter needs to be initialized
(vec4_gs_visitor::emit_prolog()).
- When EmitVertex() appears in the shader, the current contents of
output variables need to be emitted to the URB, and the vertex
counter needs to be incremented
(vec4_gs_visitor::visit(ir_emit_vertex *)).
- When generating a URB_WRITE message to output vertex data, the
current state of the vertex counter needs to be used to store a
write offset in the message header
(vec4_gs_visitor::emit_urb_write_header()).
- The URB_WRITE message that outputs vertex data needs to be sent
using GS_OPCODE_URB_WRITE, since VS_OPCODE_URB_WRITE would overwrite
the offsets in the message header
(vec4_gs_visitor::emit_urb_write_opcode()).
- At the end of a geometry shader, the final vertex count needs to be
delivered using a URB WRITE message
(vec4_gs_visitor::emit_thread_end()).
- EndPrimitive() functionality is not implemented yet
(vec4_gs_visitor::visit(ir_end_primitive *)).
- There is no support for assembly shaders
(vec4_gs_visitor::emit_program_code()).
---
src/mesa/drivers/dri/i965/Makefile.sources | 1 +
src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp | 258 ++++++++++++++++++++++
src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h | 91 ++++++++
3 files changed, 350 insertions(+)
create mode 100644 src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
create mode 100644 src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h
diff --git a/src/mesa/drivers/dri/i965/Makefile.sources b/src/mesa/drivers/dri/i965/Makefile.sources
index 60cd6e0..290cd93 100644
--- a/src/mesa/drivers/dri/i965/Makefile.sources
+++ b/src/mesa/drivers/dri/i965/Makefile.sources
@@ -87,6 +87,7 @@ i965_FILES = \
brw_vec4.cpp \
brw_vec4_copy_propagation.cpp \
brw_vec4_emit.cpp \
+ brw_vec4_gs_visitor.cpp \
brw_vec4_live_variables.cpp \
brw_vec4_reg_allocate.cpp \
brw_vec4_visitor.cpp \
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
new file mode 100644
index 0000000..9af04a2
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
@@ -0,0 +1,258 @@
+/*
+ * Copyright © 2013 Intel Corporation
+ *
+ * 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.
+ */
+
+/**
+ * \file brw_vec4_gs_visitor.cpp
+ *
+ * Geometry-shader-specific code derived from the vec4_visitor class.
+ */
+
+#include "brw_vec4_gs_visitor.h"
+
+const unsigned MAX_GS_INPUT_VERTICES = 6;
+
+namespace brw {
+
+vec4_gs_visitor::vec4_gs_visitor(struct brw_context *brw,
+ struct brw_vec4_gs_compile *c,
+ struct gl_shader_program *prog,
+ struct brw_shader *shader,
+ void *mem_ctx)
+ : vec4_visitor(brw, &c->base, &c->gp->program.Base, &c->key.base,
+ &c->prog_data.base, prog, shader, mem_ctx,
+ INTEL_DEBUG & DEBUG_GS),
+ c(c)
+{
+}
+
+
+dst_reg *
+vec4_gs_visitor::make_reg_for_system_value(ir_variable *ir)
+{
+ /* Geometry shaders don't use any system values. */
+ assert(!"Unreached");
+ return NULL;
+}
+
+
+int
+vec4_gs_visitor::setup_varying_inputs(int payload_reg, int *attribute_map)
+{
+ /* For geometry shaders there are N copies of the input attributes, where N
+ * is the number of input vertices. attribute_map[BRW_VARYING_SLOT_COUNT *
+ * i + j] represents attribute j for vertex i.
+ *
+ * Note that GS inputs are read from the VUE 256 bits (2 vec4's) at a time,
+ * so the total number of input slots that will be delivered to the GS (and
+ * thus the stride of the input arrays) is urb_read_length * 2.
+ */
+ unsigned num_input_vertices = c->gp->program.VerticesIn;
+ assert(num_input_vertices <= MAX_GS_INPUT_VERTICES);
+ unsigned input_array_stride = c->prog_data.base.urb_read_length * 2;
+
+ for (int slot = 0; slot < c->key.input_vue_map.num_slots; slot++) {
+ int varying = c->key.input_vue_map.slot_to_varying[slot];
+ for (unsigned vertex = 0; vertex < num_input_vertices; vertex++) {
+ attribute_map[BRW_VARYING_SLOT_COUNT * vertex + varying] =
+ payload_reg + input_array_stride * vertex + slot;
+ }
+ }
+
+ return payload_reg + input_array_stride * num_input_vertices;
+}
+
+
+void
+vec4_gs_visitor::setup_payload()
+{
+ int attribute_map[BRW_VARYING_SLOT_COUNT * MAX_GS_INPUT_VERTICES];
+
+ /* If a geometry shader tries to read from an input that wasn't written by
+ * the vertex shader, that produces undefined results, but it shouldn't
+ * crash anything. So initialize attribute_map to zeros--that ensures that
+ * these undefined results are read from r0.
+ */
+ memset(attribute_map, 0, sizeof(attribute_map));
+
+ int reg = 0;
+
+ /* The payload always contains important data in g0, which contains
+ * the URB handles that are passed on to the URB write at the end
+ * of the thread.
+ */
+ reg++;
+
+ reg = setup_uniforms(reg);
+
+ reg = setup_varying_inputs(reg, attribute_map);
+
+ lower_attributes_to_hw_regs(attribute_map);
+
+ this->first_non_payload_grf = reg;
+}
+
+
+void
+vec4_gs_visitor::emit_prolog()
+{
+ /* In vertex shaders, r0.2 is guaranteed to be initialized to zero. In
+ * geometry shaders, it isn't (it contains a bunch of information we don't
+ * need, like the input primitive type). We need r0.2 to be zero in order
+ * to build scratch read/write messages correctly (otherwise this value
+ * will be interpreted as a global offset, causing us to do our scratch
+ * reads/writes to garbage memory). So just set it to zero at the top of
+ * the shader.
+ */
+ this->current_annotation = "clear r0.2";
+ dst_reg r0(retype(brw_vec4_grf(0, 0), BRW_REGISTER_TYPE_UD));
+ emit(GS_OPCODE_SET_DWORD_2_IMMED, r0, 0u);
+
+ /* Create a virtual register to hold the vertex count */
+ this->vertex_count = src_reg(this, glsl_type::uint_type);
+
+ /* Initialize the vertex_count register to 0 */
+ this->current_annotation = "initialize vertex_count";
+ vec4_instruction *inst = emit(MOV(dst_reg(this->vertex_count), 0u));
+ inst->force_writemask_all = true;
+
+ this->current_annotation = NULL;
+}
+
+
+void
+vec4_gs_visitor::emit_program_code()
+{
+ /* We don't support NV_geometry_program4. */
+ assert(!"Unreached");
+}
+
+
+void
+vec4_gs_visitor::emit_thread_end()
+{
+ /* MRF 0 is reserved for the debugger, so start with message header
+ * in MRF 1.
+ */
+ int base_mrf = 1;
+
+ current_annotation = "thread end";
+ dst_reg mrf_reg(MRF, base_mrf);
+ src_reg r0(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD));
+ vec4_instruction *inst = emit(MOV(mrf_reg, r0));
+ inst->force_writemask_all = true;
+ emit(GS_OPCODE_SET_VERTEX_COUNT, mrf_reg, this->vertex_count);
+ if (INTEL_DEBUG & DEBUG_SHADER_TIME)
+ emit_shader_time_end();
+ inst = emit(GS_OPCODE_THREAD_END);
+ inst->base_mrf = base_mrf;
+ inst->mlen = 1;
+}
+
+
+void
+vec4_gs_visitor::emit_urb_write_header(int mrf)
+{
+ /* The SEND instruction that writes the vertex data to the VUE will use
+ * per_slot_offset=true, which means that DWORDs 3 and 4 of the message
+ * header specify an offset (in multiples of 256 bits) into the URB entry
+ * at which the write should take place.
+ *
+ * So we have to prepare a message header with the apropriate offset
+ * values.
+ */
+ dst_reg mrf_reg(MRF, mrf);
+ src_reg r0(retype(brw_vec8_grf(0, 0), BRW_REGISTER_TYPE_UD));
+ this->current_annotation = "URB write header";
+ vec4_instruction *inst = emit(MOV(mrf_reg, r0));
+ inst->force_writemask_all = true;
+ emit(GS_OPCODE_SET_WRITE_OFFSET, mrf_reg, this->vertex_count,
+ (uint32_t) c->prog_data.output_vertex_size_hwords);
+}
+
+
+vec4_instruction *
+vec4_gs_visitor::emit_urb_write_opcode(bool complete)
+{
+ /* We don't care whether the vertex is complete, because in general
+ * geometry shaders output multiple vertices, and we don't terminate the
+ * thread until all vertices are complete.
+ */
+ (void) complete;
+
+ vec4_instruction *inst = emit(GS_OPCODE_URB_WRITE);
+ inst->urb_write_flags = BRW_URB_WRITE_PER_SLOT_OFFSET;
+ return inst;
+}
+
+
+int
+vec4_gs_visitor::compute_array_stride(ir_dereference_array *ir)
+{
+ /* Geometry shader inputs are arrays, but they use an unusual array layout:
+ * instead of all array elements for a given geometry shader input being
+ * stored consecutively, all geometry shader inputs are interleaved into
+ * one giant array. At this stage of compilation, we assume that the
+ * stride of the array is BRW_VARYING_SLOT_COUNT. Later,
+ * setup_attributes() will remap our accesses to the actual input array.
+ */
+ ir_dereference_variable *deref_var = ir->array->as_dereference_variable();
+ if (deref_var && deref_var->var->mode == ir_var_shader_in)
+ return BRW_VARYING_SLOT_COUNT;
+ else
+ return vec4_visitor::compute_array_stride(ir);
+}
+
+
+void
+vec4_gs_visitor::visit(ir_emit_vertex *)
+{
+ this->current_annotation = "emit vertex: safety check";
+
+ /* To ensure that the vertex counter doesn't get too big, do the logic
+ * inside a conditional of the form "if (vertex_count < MAX)"
+ */
+ unsigned num_output_vertices = c->gp->program.VerticesOut;
+ emit(CMP(dst_null_d(), this->vertex_count,
+ src_reg(num_output_vertices), BRW_CONDITIONAL_L));
+ emit(IF(BRW_PREDICATE_NORMAL));
+
+ this->current_annotation = "emit vertex: vertex data";
+ emit_vertex();
+
+ this->current_annotation = "emit vertex: increment vertex count";
+ emit(ADD(dst_reg(this->vertex_count), this->vertex_count,
+ src_reg(1u)));
+
+ emit(BRW_OPCODE_ENDIF);
+
+ this->current_annotation = NULL;
+}
+
+void
+vec4_gs_visitor::visit(ir_end_primitive *)
+{
+ assert(!"Not implemented yet");
+}
+
+
+} /* namespace brw */
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h
new file mode 100644
index 0000000..e998666
--- /dev/null
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright © 2013 Intel Corporation
+ *
+ * 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.
+ */
+
+/**
+ * \file brw_vec4_gs_visitor.h
+ *
+ * Geometry-shader-specific code derived from the vec4_visitor class.
+ */
+
+#ifndef BRW_VEC4_GS_VISITOR_H
+#define BRW_VEC4_GS_VISITOR_H
+
+#include "brw_vec4.h"
+
+
+struct brw_vec4_gs_prog_key
+{
+ struct brw_vec4_prog_key base;
+
+ struct brw_vue_map input_vue_map;
+};
+
+
+/**
+ * Scratch data used when compiling a GLSL geometry shader.
+ */
+struct brw_vec4_gs_compile
+{
+ struct brw_vec4_compile base;
+ struct brw_vec4_gs_prog_key key;
+ struct brw_vec4_gs_prog_data prog_data;
+
+ struct brw_geometry_program *gp;
+};
+
+
+#ifdef __cplusplus
+namespace brw {
+
+class vec4_gs_visitor : public vec4_visitor
+{
+public:
+ vec4_gs_visitor(struct brw_context *brw,
+ struct brw_vec4_gs_compile *c,
+ struct gl_shader_program *prog,
+ struct brw_shader *shader,
+ void *mem_ctx);
+
+protected:
+ virtual dst_reg *make_reg_for_system_value(ir_variable *ir);
+ virtual void setup_payload();
+ virtual void emit_prolog();
+ virtual void emit_program_code();
+ virtual void emit_thread_end();
+ virtual void emit_urb_write_header(int mrf);
+ virtual vec4_instruction *emit_urb_write_opcode(bool complete);
+ virtual int compute_array_stride(ir_dereference_array *ir);
+ virtual void visit(ir_emit_vertex *);
+ virtual void visit(ir_end_primitive *);
+
+private:
+ int setup_varying_inputs(int payload_reg, int *attribute_map);
+
+ src_reg vertex_count;
+ const struct brw_vec4_gs_compile * const c;
+};
+
+} /* namespace brw */
+#endif /* __cplusplus */
+
+#endif /* BRW_VEC4_GS_VISITOR_H */
--
1.8.3.4
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