From: Eric Anholt Date: Thu, 23 Feb 2012 19:51:04 +0000 (-0800) Subject: glsl: Improve the local dead code optimization to eliminate unused channels. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=05c200bac049ed4760f0af6786e463e2520b9c9c;p=mesa.git glsl: Improve the local dead code optimization to eliminate unused channels. Total instructions: 261582 -> 261316 135/2147 programs affected (6.3%) 36752 -> 36486 instructions in affected programs (0.7% reduction) This excludes a tropics shader that now gets 16-wide mode and throws off the numbers. 5 shaders are hurt: two extra MOVs in 4 tropics shaders it looks like because we don't split register names according to independent webs, and one gstreamer shader where it looks like try_rewrite_rhs_to_dst() is falling on its face. This should also help avoid a regression in VSes from idr's ARB programs to GLSL work. --- diff --git a/src/glsl/opt_dead_code_local.cpp b/src/glsl/opt_dead_code_local.cpp index a81a38fff0f..4af78a72cc3 100644 --- a/src/glsl/opt_dead_code_local.cpp +++ b/src/glsl/opt_dead_code_local.cpp @@ -43,16 +43,20 @@ static bool debug = false; class assignment_entry : public exec_node { public: - assignment_entry(ir_variable *lhs, ir_instruction *ir) + assignment_entry(ir_variable *lhs, ir_assignment *ir) { assert(lhs); assert(ir); this->lhs = lhs; this->ir = ir; + this->available = ir->write_mask; } ir_variable *lhs; - ir_instruction *ir; + ir_assignment *ir; + + /* bitmask of xyzw channels written that haven't been used so far. */ + int available; }; class kill_for_derefs_visitor : public ir_hierarchical_visitor { @@ -62,23 +66,52 @@ public: this->assignments = assignments; } - virtual ir_visitor_status visit(ir_dereference_variable *ir) + void kill_channels(ir_variable *const var, int used) { - ir_variable *const var = ir->variable_referenced(); - foreach_iter(exec_list_iterator, iter, *this->assignments) { assignment_entry *entry = (assignment_entry *)iter.get(); if (entry->lhs == var) { - if (debug) - printf("kill %s\n", entry->lhs->name); - entry->remove(); + if (var->type->is_scalar() || var->type->is_vector()) { + if (debug) + printf("kill %s (0x%01x - 0x%01x)\n", entry->lhs->name, + entry->available, used); + entry->available &= ~used; + if (!entry->available) + entry->remove(); + } else { + if (debug) + printf("kill %s\n", entry->lhs->name); + entry->remove(); + } } } + } + + virtual ir_visitor_status visit(ir_dereference_variable *ir) + { + kill_channels(ir->var, ~0); return visit_continue; } + virtual ir_visitor_status visit(ir_swizzle *ir) + { + ir_dereference_variable *deref = ir->val->as_dereference_variable(); + if (!deref) + return visit_continue; + + int used = 0; + used |= 1 << ir->mask.x; + used |= 1 << ir->mask.y; + used |= 1 << ir->mask.z; + used |= 1 << ir->mask.w; + + kill_channels(deref->var, used); + + return visit_continue_with_parent; + } + private: exec_list *assignments; }; @@ -130,21 +163,91 @@ process_assignment(void *ctx, ir_assignment *ir, exec_list *assignments) assert(var); /* Now, check if we did a whole-variable assignment. */ - if (!ir->condition && (ir->whole_variable_written() != NULL)) { - /* We did a whole-variable assignment. So, any instruction in - * the assignment list with the same LHS is dead. - */ - if (debug) - printf("looking for %s to remove\n", var->name); - foreach_iter(exec_list_iterator, iter, *assignments) { - assignment_entry *entry = (assignment_entry *)iter.get(); + if (!ir->condition) { + ir_dereference_variable *deref_var = ir->lhs->as_dereference_variable(); - if (entry->lhs == var) { - if (debug) - printf("removing %s\n", var->name); - entry->ir->remove(); - entry->remove(); - progress = true; + /* If it's a vector type, we can do per-channel elimination of + * use of the RHS. + */ + if (deref_var && (deref_var->var->type->is_scalar() || + deref_var->var->type->is_vector())) { + + if (debug) + printf("looking for %s.0x%01x to remove\n", var->name, + ir->write_mask); + + foreach_iter(exec_list_iterator, iter, *assignments) { + assignment_entry *entry = (assignment_entry *)iter.get(); + + if (entry->lhs != var) + continue; + + int remove = entry->available & ir->write_mask; + if (debug) { + printf("%s 0x%01x - 0x%01x = 0x%01x\n", + var->name, + entry->ir->write_mask, + remove, entry->ir->write_mask & ~remove); + } + if (remove) { + progress = true; + + if (debug) { + printf("rewriting:\n "); + entry->ir->print(); + printf("\n"); + } + + entry->ir->write_mask &= ~remove; + entry->available &= ~remove; + if (entry->ir->write_mask == 0) { + /* Delete the dead assignment. */ + entry->ir->remove(); + entry->remove(); + } else { + void *mem_ctx = ralloc_parent(entry->ir); + /* Reswizzle the RHS arguments according to the new + * write_mask. + */ + unsigned components[4]; + unsigned channels = 0; + unsigned next = 0; + + for (int i = 0; i < 4; i++) { + if ((entry->ir->write_mask | remove) & (1 << i)) { + if (!(remove & (1 << i))) + components[channels++] = next; + next++; + } + } + + entry->ir->rhs = new(mem_ctx) ir_swizzle(entry->ir->rhs, + components, + channels); + if (debug) { + printf("to:\n "); + entry->ir->print(); + printf("\n"); + } + } + } + } + } else if (ir->whole_variable_written() != NULL) { + /* We did a whole-variable assignment. So, any instruction in + * the assignment list with the same LHS is dead. + */ + if (debug) + printf("looking for %s to remove\n", var->name); + foreach_iter(exec_list_iterator, iter, *assignments) { + assignment_entry *entry = (assignment_entry *)iter.get(); + + if (entry->lhs == var) { + if (debug) + printf("removing %s\n", var->name); + entry->ir->remove(); + entry->remove(); + progress = true; + } } } } @@ -160,7 +263,7 @@ process_assignment(void *ctx, ir_assignment *ir, exec_list *assignments) foreach_iter(exec_list_iterator, iter, *assignments) { assignment_entry *entry = (assignment_entry *)iter.get(); - printf(" %s\n", entry->lhs->name); + printf(" %s (0x%01x)\n", entry->lhs->name, entry->available); } }