mesa: remove obsolete matrix comment

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

diff --git a/src/glsl/loop_analysis.cpp b/src/glsl/loop_analysis.cpp
index 9bba6a97c488ac198482b7512ca198d71a3bbb61..6a0e4da51004cd1c67547f631f3e770c7204bbc5 100644 (file)
--- a/src/glsl/loop_analysis.cpp
+++ b/src/glsl/loop_analysis.cpp
@@ -110,6 +110,8 @@ public:
    virtual ir_visitor_status visit(ir_loop_jump *);
    virtual ir_visitor_status visit(ir_dereference_variable *);
 
+   virtual ir_visitor_status visit_enter(ir_call *);
+
    virtual ir_visitor_status visit_enter(ir_loop *);
    virtual ir_visitor_status visit_leave(ir_loop *);
    virtual ir_visitor_status visit_enter(ir_assignment *);
@@ -152,6 +154,21 @@ loop_analysis::visit(ir_loop_jump *ir)
 }
 
 
+ir_visitor_status
+loop_analysis::visit_enter(ir_call *ir)
+{
+   /* If we're not somewhere inside a loop, there's nothing to do. */
+   if (this->state.is_empty())
+      return visit_continue;
+
+   loop_variable_state *const ls =
+      (loop_variable_state *) this->state.get_head();
+
+   ls->contains_calls = true;
+   return visit_continue_with_parent;
+}
+
+
 ir_visitor_status
 loop_analysis::visit(ir_dereference_variable *ir)
 {
@@ -209,6 +226,17 @@ loop_analysis::visit_leave(ir_loop *ir)
    loop_variable_state *const ls =
       (loop_variable_state *) this->state.pop_head();
 
+   /* Function calls may contain side effects.  These could alter any of our
+    * variables in ways that cannot be known, and may even terminate shader
+    * execution (say, calling discard in the fragment shader).  So we can't
+    * rely on any of our analysis about assignments to variables.
+    *
+    * We could perform some conservative analysis (prove there's no statically
+    * possible assignment, etc.) but it isn't worth it for now; function
+    * inlining will allow us to unroll loops anyway.
+    */
+   if (ls->contains_calls)
+      return visit_continue;
 
    foreach_list(node, &ir->body_instructions) {
       /* Skip over declarations at the start of a loop.