[Mesa-dev] [PATCH 1/2] glsl hierarchical visitor: Do not overwrite base_ir for parameter lists.

[Paul Berry]

This patch fixes a bug in ir_hirearchical_visitor: when traversing an
exec_list representing the formal or actual parameters of a function,
it modified base_ir to point to each parameter in turn, rather than
leaving it as a pointer to the enclosing statement.  This was a
problem, since base_ir is used by visitor classes to locate the
statement containing the node being visited (usually so that
additional statements can be inserted before or after it).  Without
this fix, visitors might attempt to insert statements into parameter
lists.
---
 src/glsl/ir_hierarchical_visitor.h |    3 ++-
 src/glsl/ir_hv_accept.cpp          |   21 +++++++++++++++------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/glsl/ir_hierarchical_visitor.h b/src/glsl/ir_hierarchical_visitor.h
index dc177f5..bba046d 100644
--- a/src/glsl/ir_hierarchical_visitor.h
+++ b/src/glsl/ir_hierarchical_visitor.h
@@ -178,6 +178,7 @@ void visit_tree(ir_instruction *ir,
 		void (*callback)(class ir_instruction *ir, void *data),
 		void *data);
 
-ir_visitor_status visit_list_elements(ir_hierarchical_visitor *v, exec_list *l);
+ir_visitor_status visit_list_elements(ir_hierarchical_visitor *v, exec_list *l,
+                                      bool statement_list = true);
 
 #endif /* IR_HIERARCHICAL_VISITOR_H */
diff --git a/src/glsl/ir_hv_accept.cpp b/src/glsl/ir_hv_accept.cpp
index d33fc85..0e78fda 100644
--- a/src/glsl/ir_hv_accept.cpp
+++ b/src/glsl/ir_hv_accept.cpp
@@ -30,7 +30,13 @@
  */
 
 /**
- * Process a list of nodes using a hierarchical vistor
+ * Process a list of nodes using a hierarchical vistor.
+ *
+ * If statement_list is true (the default), this is a list of statements, so
+ * v->base_ir will be set to point to each statement just before iterating
+ * over it, and restored after iteration is complete.  If statement_list is
+ * false, this is a list that appears inside a statement (e.g. a parameter
+ * list), so v->base_ir will be left alone.
  *
  * \warning
  * This function will operate correctly if a node being processed is removed
@@ -38,19 +44,22 @@
  * processed, some of the added nodes may not be processed.
  */
 ir_visitor_status
-visit_list_elements(ir_hierarchical_visitor *v, exec_list *l)
+visit_list_elements(ir_hierarchical_visitor *v, exec_list *l,
+                    bool statement_list)
 {
    ir_instruction *prev_base_ir = v->base_ir;
 
    foreach_list_safe(n, l) {
       ir_instruction *const ir = (ir_instruction *) n;
-      v->base_ir = ir;
+      if (statement_list)
+         v->base_ir = ir;
       ir_visitor_status s = ir->accept(v);
 
       if (s != visit_continue)
 	 return s;
    }
-   v->base_ir = prev_base_ir;
+   if (statement_list)
+      v->base_ir = prev_base_ir;
 
    return visit_continue;
 }
@@ -129,7 +138,7 @@ ir_function::accept(ir_hierarchical_visitor *v)
    if (s != visit_continue)
       return (s == visit_continue_with_parent) ? visit_continue : s;
 
-   s = visit_list_elements(v, &this->signatures);
+   s = visit_list_elements(v, &this->signatures, false);
    return (s == visit_stop) ? s : v->visit_leave(this);
 }
 
@@ -317,7 +326,7 @@ ir_call::accept(ir_hierarchical_visitor *v)
    if (s != visit_continue)
       return (s == visit_continue_with_parent) ? visit_continue : s;
 
-   s = visit_list_elements(v, &this->actual_parameters);
+   s = visit_list_elements(v, &this->actual_parameters, false);
    if (s == visit_stop)
       return s;
 
-- 
1.7.6