glsl: Make a function to express a GLSL version ir human-readable form.

[mesa.git] / src / glsl / opt_constant_propagation.cpp

diff --git a/src/glsl/opt_constant_propagation.cpp b/src/glsl/opt_constant_propagation.cpp
index af77e4906896173ce421e8491a176d82c8cc05e1..a03811999a0657e726c03ed8bd72a23f0ac1be88 100644 (file)
--- a/src/glsl/opt_constant_propagation.cpp
+++ b/src/glsl/opt_constant_propagation.cpp
@@ -41,6 +41,8 @@
 #include "ir_optimization.h"
 #include "glsl_types.h"
 
+namespace {
+
 class acp_entry : public exec_node
 {
 public:
@@ -90,6 +92,7 @@ public:
    ir_constant_propagation_visitor()
    {
       progress = false;
+      killed_all = false;
       mem_ctx = ralloc_context(0);
       this->acp = new(mem_ctx) exec_list;
       this->kills = new(mem_ctx) exec_list;
@@ -241,7 +244,26 @@ ir_constant_propagation_visitor::visit_leave(ir_assignment *ir)
    if (this->in_assignee)
       return visit_continue;
 
-   kill(ir->lhs->variable_referenced(), ir->write_mask);
+   unsigned kill_mask = ir->write_mask;
+   if (ir->lhs->as_dereference_array()) {
+      /* The LHS of the assignment uses an array indexing operator (e.g. v[i]
+       * = ...;).  Since we only try to constant propagate vectors and
+       * scalars, this means that either (a) array indexing is being used to
+       * select a vector component, or (b) the variable in question is neither
+       * a scalar or a vector, so we don't care about it.  In the former case,
+       * we want to kill the whole vector, since in general we can't predict
+       * which vector component will be selected by array indexing.  In the
+       * latter case, it doesn't matter what we do, so go ahead and kill the
+       * whole variable anyway.
+       *
+       * Note that if the array index is constant (e.g. v[2] = ...;), we could
+       * in principle be smarter, but we don't need to, because a future
+       * optimization pass will convert it to a simple assignment with the
+       * correct mask.
+       */
+      kill_mask = ~0;
+   }
+   kill(ir->lhs->variable_referenced(), kill_mask);
 
    add_constant(ir);
 
@@ -259,7 +281,7 @@ ir_visitor_status
 ir_constant_propagation_visitor::visit_enter(ir_call *ir)
 {
    /* Do constant propagation on call parameters, but skip any out params */
-   exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator();
+   exec_list_iterator sig_param_iter = ir->callee->parameters.iterator();
    foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
       ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
       ir_rvalue *param = (ir_rvalue *)iter.get();
@@ -431,6 +453,8 @@ ir_constant_propagation_visitor::add_constant(ir_assignment *ir)
    this->acp->push_tail(entry);
 }
 
+} /* unnamed namespace */
+
 /**
  * Does a constant propagation pass on the code present in the instruction stream.
  */