[gtk+/wip/otte/shader: 125/150] gskslexpression: Fold constant expressions into SPIRV

[Benjamin Otte <otte src gnome org>]

commit 7dd14e19938455ca05248e3752e1ce1a0d595157
Author: Benjamin Otte <otte redhat com>
Date:   Thu Oct 12 02:27:28 2017 +0200

    gskslexpression: Fold constant expressions into SPIRV
    
    If an expression is constant, always get the constant expression and
    write it to the SPIRV file instead of doing an evaluation.
    
    This has immense benefits when dealing with initializations, because
    vec4(1, 2, 3, 4) will actually result in a constant instead of first
    creating 4 integers, manually converting each of them to float before
    calling the constructor. Yuck.

 gsk/gskslexpression.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/gsk/gskslexpression.c b/gsk/gskslexpression.c
index 3a4f0f6..8e000ff 100644
--- a/gsk/gskslexpression.c
+++ b/gsk/gskslexpression.c
@@ -2775,8 +2775,18 @@ gsk_sl_expression_write_spv (const GskSlExpression *expression,
                              GskSpvWriter          *writer)
 {
   GskSpvAccessChain *chain;
+  GskSlValue *constant;
   guint32 result_id;
 
+  constant = gsk_sl_expression_get_constant (expression);
+  if (constant)
+    {
+      result_id = gsk_spv_writer_get_id_for_value (writer, constant);
+      gsk_sl_value_free (constant);
+
+      return result_id;
+    }
+
   chain = gsk_sl_expression_get_spv_access_chain (expression, writer);
   if (chain)
     {