[Mesa-dev] [PATCH 2/5] glsl: Fix implicit conversions in non-constructor function calls

[Chad Versace]

Context
-------
In ast_function_expression::hir(), parameter_lists_match() checks if the
function call's actual parameter list matches the signature's parameter
list, where the match may require implicit conversion of some arguments.
To check if an implicit conversion exists between individual arguments,
type_compare() is used.

Problems
--------
type_compare() allowed the following illegal implicit conversions:
    bool -> float
    bvecN -> vecN

    int -> uint
    ivecN -> uvecN

    uint -> int
    uvecN -> ivecN

Change
------
type_compare() is buggy, so replace it with glsl_type::can_be_implicitly_converted_to().
This comprises a rewrite of parameter_lists_match().

Fixes piglit:spec/glsl-1.20/compiler/built-in-functions/outerProduct-bvec*.vert

v2:
    - Fix squash issue identified by Ken.
    - Replace 'continue' statements with more natrual 'break' idiom, as
      requested by Ken.

Note: This is a candidate for the 7.10 and 7.11 branches.
CC: Ian Romanick <ian.d.romanick at intel.com>
CC: Kenneth Graunke <kenneth at whitecape.org>
Signed-off-by: Chad Versace <chad at chad-versace.us>
---
 src/glsl/ir_function.cpp |   46 +++++++++++++++++++++++++++++-----------------
 1 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/src/glsl/ir_function.cpp b/src/glsl/ir_function.cpp
index 0f2f1a0..eca0079 100644
--- a/src/glsl/ir_function.cpp
+++ b/src/glsl/ir_function.cpp
@@ -85,12 +85,25 @@ type_compare(const glsl_type *a, const glsl_type *b)
 }
 
 
+/**
+ * \brief Check if two parameter lists match.
+ *
+ * \param list_a Parameters of the function definition.
+ * \param list_b Actual parameters passed to the function.
+ * \return If an exact match, return 0.
+ *         If an inexact match requiring implicit conversion, return 1.
+ *         If not a match, return -1.
+ * \see matching_signature()
+ */
 static int
 parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 {
    const exec_node *node_a = list_a->head;
    const exec_node *node_b = list_b->head;
-   int total_score = 0;
+
+   /* This is set to true if there is an inexact match requiring an implicit
+    * conversion. */
+   bool inexact_match = false;
 
    for (/* empty */
 	; !node_a->is_tail_sentinel()
@@ -106,12 +119,11 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
       const ir_variable *const param = (ir_variable *) node_a;
       const ir_instruction *const actual = (ir_instruction *) node_b;
 
-      /* Determine whether or not the types match.  If the types are an
-       * exact match, the match score is zero.  If the types don't match
-       * but the actual parameter can be coerced to the type of the declared
-       * parameter, the match score is one.
-       */
-      int score;
+      if (param->type == actual->type)
+	 continue;
+
+      /* Try to find an implicit conversion from actual to param. */
+      inexact_match = true;
       switch ((enum ir_variable_mode)(param->mode)) {
       case ir_var_auto:
       case ir_var_uniform:
@@ -125,11 +137,13 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 
       case ir_var_const_in:
       case ir_var_in:
-	 score = type_compare(param->type, actual->type);
+	 if (!actual->type->can_implicitly_convert_to(param->type))
+	    return -1;
 	 break;
 
       case ir_var_out:
-	 score = type_compare(actual->type, param->type);
+	 if (!param->type->can_implicitly_convert_to(actual->type))
+	    return -1;
 	 break;
 
       case ir_var_inout:
@@ -137,17 +151,12 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 	  * there is int -> float but no float -> int), inout parameters must
 	  * be exact matches.
 	  */
-	 score = (type_compare(actual->type, param->type) == 0) ? 0 : -1;
-	 break;
+	 return -1;
 
       default:
 	 assert(false);
-      }
-
-      if (score < 0)
 	 return -1;
-
-      total_score += score;
+      }
    }
 
    /* If all of the parameters from the other parameter list have been
@@ -157,7 +166,10 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
    if (!node_b->is_tail_sentinel())
       return -1;
 
-   return total_score;
+   if (inexact_match)
+      return 1;
+   else
+      return 0;
 }
 
 
-- 
1.7.6