Mesa (staging/19.0): glsl/lower_vector_derefs: Don't use a temporary for TCS outputs
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gitlab-mirror at kemper.freedesktop.org
Wed Mar 13 21:29:21 UTC 2019
Module: Mesa
Branch: staging/19.0
Commit: 95b001cb190dbc0ec71d760e1d9c457c1a3e4f70
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=95b001cb190dbc0ec71d760e1d9c457c1a3e4f70
Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date: Mon Mar 11 20:43:15 2019 -0500
glsl/lower_vector_derefs: Don't use a temporary for TCS outputs
Tessellation control shader outputs act as if they have memory backing
them and you can have multiple writes to different components of the
same vector in-flight at the same time. When this happens, the load vec
store pattern that gets used by ir_triop_vector_insert doesn't yield the
correct results. Instead, just emit a sequence of conditional
assignments.
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: mesa-stable at lists.freedesktop.org
(cherry picked from commit bd17bdc56b34a08c421172df27fe07294c7a7024)
---
src/compiler/glsl/lower_vector_derefs.cpp | 74 ++++++++++++++++++++++++++-----
1 file changed, 64 insertions(+), 10 deletions(-)
diff --git a/src/compiler/glsl/lower_vector_derefs.cpp b/src/compiler/glsl/lower_vector_derefs.cpp
index 6cd9a2d819a..2aae30d8201 100644
--- a/src/compiler/glsl/lower_vector_derefs.cpp
+++ b/src/compiler/glsl/lower_vector_derefs.cpp
@@ -32,8 +32,9 @@ namespace {
class vector_deref_visitor : public ir_rvalue_enter_visitor {
public:
- vector_deref_visitor()
- : progress(false)
+ vector_deref_visitor(void *mem_ctx, gl_shader_stage shader_stage)
+ : progress(false), shader_stage(shader_stage),
+ factory(&factory_instructions, mem_ctx)
{
}
@@ -45,6 +46,9 @@ public:
virtual ir_visitor_status visit_enter(ir_assignment *ir);
bool progress;
+ gl_shader_stage shader_stage;
+ exec_list factory_instructions;
+ ir_factory factory;
};
} /* anonymous namespace */
@@ -65,13 +69,63 @@ vector_deref_visitor::visit_enter(ir_assignment *ir)
ir_constant *old_index_constant =
deref->array_index->constant_expression_value(mem_ctx);
if (!old_index_constant) {
- ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
- new_lhs->type,
- new_lhs->clone(mem_ctx, NULL),
- ir->rhs,
- deref->array_index);
- ir->write_mask = (1 << new_lhs->type->vector_elements) - 1;
- ir->set_lhs(new_lhs);
+ if (shader_stage == MESA_SHADER_TESS_CTRL &&
+ deref->variable_referenced()->data.mode == ir_var_shader_out) {
+ /* Tessellation control shader outputs act as if they have memory
+ * backing them and if we have writes from multiple threads
+ * targeting the same vec4 (this can happen for patch outputs), the
+ * load-vec-store pattern of ir_triop_vector_insert doesn't work.
+ * Instead, we have to lower to a series of conditional write-masked
+ * assignments.
+ */
+ ir_variable *const src_temp =
+ factory.make_temp(ir->rhs->type, "scalar_tmp");
+
+ /* The newly created variable declaration goes before the assignment
+ * because we're going to set it as the new LHS.
+ */
+ ir->insert_before(factory.instructions);
+ ir->set_lhs(new(mem_ctx) ir_dereference_variable(src_temp));
+
+ ir_variable *const arr_index =
+ factory.make_temp(deref->array_index->type, "index_tmp");
+ factory.emit(assign(arr_index, deref->array_index));
+
+ for (unsigned i = 0; i < new_lhs->type->vector_elements; i++) {
+ ir_constant *const cmp_index =
+ ir_constant::zero(factory.mem_ctx, deref->array_index->type);
+ cmp_index->value.u[0] = i;
+
+ ir_rvalue *const lhs_clone = new_lhs->clone(factory.mem_ctx, NULL);
+ ir_dereference_variable *const src_temp_deref =
+ new(mem_ctx) ir_dereference_variable(src_temp);
+
+ if (new_lhs->ir_type != ir_type_swizzle) {
+ assert(lhs_clone->as_dereference());
+ ir_assignment *cond_assign =
+ new(mem_ctx) ir_assignment(lhs_clone->as_dereference(),
+ src_temp_deref,
+ equal(arr_index, cmp_index),
+ WRITEMASK_X << i);
+ factory.emit(cond_assign);
+ } else {
+ ir_assignment *cond_assign =
+ new(mem_ctx) ir_assignment(swizzle(lhs_clone, i, 1),
+ src_temp_deref,
+ equal(arr_index, cmp_index));
+ factory.emit(cond_assign);
+ }
+ }
+ ir->insert_after(factory.instructions);
+ } else {
+ ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
+ new_lhs->type,
+ new_lhs->clone(mem_ctx, NULL),
+ ir->rhs,
+ deref->array_index);
+ ir->write_mask = (1 << new_lhs->type->vector_elements) - 1;
+ ir->set_lhs(new_lhs);
+ }
} else if (new_lhs->ir_type != ir_type_swizzle) {
ir->set_lhs(new_lhs);
ir->write_mask = 1 << old_index_constant->get_uint_component(0);
@@ -105,7 +159,7 @@ vector_deref_visitor::handle_rvalue(ir_rvalue **rv)
bool
lower_vector_derefs(gl_linked_shader *shader)
{
- vector_deref_visitor v;
+ vector_deref_visitor v(shader->ir, shader->Stage);
visit_list_elements(&v, shader->ir);
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