glsl: Simplify aggregate type inference to prepare for ARB_arrays_of_arrays.

Most of the time it is not necessary to perform type inference to
compile GLSL; the type of every expression can be inferred from the
contents of the expression itself (and previous type declarations).
The exception is aggregate initializers: their type is determined by
the LHS of the variable being assigned to.  For example, in the
statement:

   mat2 foo = { { 1, 2 }, { 3, 4 } };

the type of { 1, 2 } is only known to be vec2 (as opposed to, say,
ivec2, uvec2, int[2], or a struct) because of the fact that the result
is being assigned to a mat2.

Previous to this patch, we handled this situation by doing some type
inference during parsing: when parsing a declaration like the one
above, we would call _mesa_set_aggregate_type(), which would infer the
type of each aggregate initializer and store it in the corresponding
ast_aggregate_initializer::constructor_type field.  Since this
happened at parse time, we couldn't do the type inference using
glsl_type objects; we had to use ast_type_specifiers, which are much
more awkward to work with.  Things are about to get more complicated
when we add support for ARB_arrays_of_arrays.

This patch simplifies things by postponing the call to
_mesa_set_aggregate_type() until ast-to-hir time, when we have access
to glsl_type objects.  As a side benefit, we only need to have one
call to _mesa_set_aggregate_type() now, instead of six.

Reviewed-by: Matt Turner <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index 4cc8eb18dc8..8d13610e426 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -2593,6 +2593,13 @@ process_initializer(ir_variable *var, ast_declaration *decl,
 		       ? "attribute" : "varying");
    }
 
+   /* If the initializer is an ast_aggregate_initializer, recursively store
+    * type information from the LHS into it, so that its hir() function can do
+    * type checking.
+    */
+   if (decl->initializer->oper == ast_aggregate)
+      _mesa_ast_set_aggregate_type(var->type, decl->initializer);
+
    ir_dereference *const lhs = new(state) ir_dereference_variable(var);
    ir_rvalue *rhs = decl->initializer->hir(initializer_instructions,
 					   state);