glsl: Introduce a new "const_in" variable mode.

This annotation is for an "in" function parameter for which it is only legal
to pass constant expressions.  The only known example of this, currently,
is the textureOffset functions.

This should never be used for globals.

12 files changed, 36 insertions, 4 deletions

diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index b3635bf686..b0f95dd73b 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -132,6 +132,9 @@ match_function_by_name(exec_list *instructions, const char *name,
       /* Verify that 'out' and 'inout' actual parameters are lvalues.  This
        * isn't done in ir_function::matching_signature because that function
        * cannot generate the necessary diagnostics.
+       *
+       * Also, validate that 'const_in' formal parameters (an extension of our
+       * IR) correspond to ir_constant actual parameters.
        */
       exec_list_iterator actual_iter = actual_parameters->iterator();
       exec_list_iterator formal_iter = sig->parameters.iterator();
@@ -143,6 +146,12 @@ match_function_by_name(exec_list *instructions, const char *name,
 	 assert(actual != NULL);
 	 assert(formal != NULL);
 
+	 if (formal->mode == ir_var_const_in && !actual->as_constant()) {
+	    _mesa_glsl_error(loc, state,
+			     "parameter `%s' must be a constant expression",
+			     formal->name);
+	 }
+
 	 if ((formal->mode == ir_var_out)
 	     || (formal->mode == ir_var_inout)) {
 	    const char *mode = NULL;
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index cc508e2a42..fc356ba527 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -1379,6 +1379,21 @@ ir_function_signature::ir_function_signature(const glsl_type *return_type)
 }
 
 
+static bool
+modes_match(unsigned a, unsigned b)
+{
+   if (a == b)
+      return true;
+
+   /* Accept "in" vs. "const in" */
+   if ((a == ir_var_const_in && b == ir_var_in) ||
+       (b == ir_var_const_in && a == ir_var_in))
+      return true;
+
+   return false;
+}
+
+
 const char *
 ir_function_signature::qualifiers_match(exec_list *params)
 {
@@ -1391,7 +1406,7 @@ ir_function_signature::qualifiers_match(exec_list *params)
       ir_variable *b = (ir_variable *)iter_b.get();
 
       if (a->read_only != b->read_only ||
-	  a->mode != b->mode ||
+	  !modes_match(a->mode, b->mode) ||
 	  a->interpolation != b->interpolation ||
 	  a->centroid != b->centroid) {
 
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 878c1779d8..74a8b06b1a 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -222,6 +222,7 @@ enum ir_variable_mode {
    ir_var_in,
    ir_var_out,
    ir_var_inout,
+   ir_var_const_in,	/**< "in" param that must be a constant expression */
    ir_var_system_value, /**< Ex: front-face, instance-id, etc. */
    ir_var_temporary	/**< Temporary variable generated during compilation. */
 };
diff --git a/src/glsl/ir_function.cpp b/src/glsl/ir_function.cpp
index 8db70119ec..caee9296af 100644
--- a/src/glsl/ir_function.cpp
+++ b/src/glsl/ir_function.cpp
@@ -123,6 +123,7 @@ parameter_lists_match(const exec_list *list_a, const exec_list *list_b)
 	 assert(0);
 	 return -1;
 
+      case ir_var_const_in:
       case ir_var_in:
 	 score = type_compare(param->type, actual->type);
 	 break;
diff --git a/src/glsl/ir_print_visitor.cpp b/src/glsl/ir_print_visitor.cpp
index 630850048f..82ccc722fa 100644
--- a/src/glsl/ir_print_visitor.cpp
+++ b/src/glsl/ir_print_visitor.cpp
@@ -97,7 +97,7 @@ void ir_print_visitor::visit(ir_variable *ir)
    const char *const cent = (ir->centroid) ? "centroid " : "";
    const char *const inv = (ir->invariant) ? "invariant " : "";
    const char *const mode[] = { "", "uniform ", "in ", "out ", "inout ",
-			        "sys ", "temporary " };
+			        "const_in ", "sys ", "temporary " };
    const char *const interp[] = { "", "flat", "noperspective" };
 
    printf("(%s%s%s%s) ",
diff --git a/src/glsl/ir_reader.cpp b/src/glsl/ir_reader.cpp
index 9ed3d23508..af85e06ae0 100644
--- a/src/glsl/ir_reader.cpp
+++ b/src/glsl/ir_reader.cpp
@@ -397,6 +397,8 @@ ir_reader::read_declaration(s_expression *expr)
 	 var->mode = ir_var_auto;
       } else if (strcmp(qualifier->value(), "in") == 0) {
 	 var->mode = ir_var_in;
+      } else if (strcmp(qualifier->value(), "const_in") == 0) {
+	 var->mode = ir_var_const_in;
       } else if (strcmp(qualifier->value(), "out") == 0) {
 	 var->mode = ir_var_out;
       } else if (strcmp(qualifier->value(), "inout") == 0) {
diff --git a/src/glsl/ir_variable.cpp b/src/glsl/ir_variable.cpp
index 73da28faf4..18a3e0fb0d 100644
--- a/src/glsl/ir_variable.cpp
+++ b/src/glsl/ir_variable.cpp
@@ -45,6 +45,7 @@ add_variable(const char *name, enum ir_variable_mode mode, int slot,
    switch (var->mode) {
    case ir_var_auto:
    case ir_var_in:
+   case ir_var_const_in:
    case ir_var_uniform:
    case ir_var_system_value:
       var->read_only = true;
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 3d1b8a2f70..c7fb62437d 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -299,6 +299,7 @@ mode_string(const ir_variable *var)
    case ir_var_out:     return "shader output";
    case ir_var_inout:   return "shader inout";
 
+   case ir_var_const_in:
    case ir_var_temporary:
    default:
       assert(!"Should not get here.");
diff --git a/src/glsl/lower_variable_index_to_cond_assign.cpp b/src/glsl/lower_variable_index_to_cond_assign.cpp
index 147a6aea1e..8eb1612f0a 100644
--- a/src/glsl/lower_variable_index_to_cond_assign.cpp
+++ b/src/glsl/lower_variable_index_to_cond_assign.cpp
@@ -255,6 +255,7 @@ public:
       case ir_var_uniform:
 	 return this->lower_uniforms;
       case ir_var_in:
+      case ir_var_const_in:
 	 return (var->location == -1) ? this->lower_temps : this->lower_inputs;
       case ir_var_out:
 	 return (var->location == -1) ? this->lower_temps : this->lower_outputs;
diff --git a/src/glsl/opt_constant_folding.cpp b/src/glsl/opt_constant_folding.cpp
index d69ca75fe0..599b21525d 100644
--- a/src/glsl/opt_constant_folding.cpp
+++ b/src/glsl/opt_constant_folding.cpp
@@ -122,7 +122,7 @@ ir_constant_folding_visitor::visit_enter(ir_call *ir)
       ir_rvalue *param_rval = (ir_rvalue *)iter.get();
       ir_variable *sig_param = (ir_variable *)sig_iter.get();
 
-      if (sig_param->mode == ir_var_in) {
+      if (sig_param->mode == ir_var_in || sig_param->mode == ir_var_const_in) {
 	 ir_rvalue *new_param = param_rval;
 
 	 handle_rvalue(&new_param);
diff --git a/src/glsl/opt_function_inlining.cpp b/src/glsl/opt_function_inlining.cpp
index a0449a7427..2e7831dcbd 100644
--- a/src/glsl/opt_function_inlining.cpp
+++ b/src/glsl/opt_function_inlining.cpp
@@ -165,6 +165,7 @@ ir_call::generate_inline(ir_instruction *next_ir)
 
       /* Move the actual param into our param variable if it's an 'in' type. */
       if (parameters[i] && (sig_param->mode == ir_var_in ||
+			    sig_param->mode == ir_var_const_in ||
 			    sig_param->mode == ir_var_inout)) {
 	 ir_assignment *assign;
 
diff --git a/src/glsl/opt_tree_grafting.cpp b/src/glsl/opt_tree_grafting.cpp
index ae77408dbe..1ef940f9c7 100644
--- a/src/glsl/opt_tree_grafting.cpp
+++ b/src/glsl/opt_tree_grafting.cpp
@@ -195,7 +195,7 @@ ir_tree_grafting_visitor::visit_enter(ir_call *ir)
       ir_rvalue *ir = (ir_rvalue *)iter.get();
       ir_rvalue *new_ir = ir;
 
-      if (sig_param->mode != ir_var_in)
+      if (sig_param->mode != ir_var_in && sig_param->mode != ir_var_const_in)
 	 continue;
 
       if (do_graft(&new_ir)) {