nir: add new constant folding infrastructure

Add a required field to the Opcode class, const_expr, that contains an
expression or statement that computes the result of the opcode given known
constant inputs. Then take those const_expr's and expand them into a function
that takes an opcode and an array of constant inputs and spits out the constant
result. This means that when adding opcodes, there's one less place to update,
and almost all the opcodes are self-documenting since the information on how to
compute the result is right next to the definition.

The helper functions in nir_constant_expressions.c were taken from
ir_constant_expressions.cpp.

v3 Jason Ekstrand <[email protected]>
 - Use mako to generate one function per opcode instead of doing piles of
   string splicing

v4 Jason Ekstrand <[email protected]>
 - More comments and better indentation in the mako
 - Add a description of the constant expression language in nir_opcodes.py
 - Added nir_constant_expressions.py to EXTRA_DIST in Makefile.am

Signed-off-by: Jason Ekstrand <[email protected]>
Reviewed-by: Connor Abbott <[email protected]>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/glsl/nir/nir_constant_expressions.h b/src/glsl/nir/nir_constant_expressions.h
new file mode 100644
index 00000000000..97997f2e514
--- /dev/null
+++ b/src/glsl/nir/nir_constant_expressions.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright © 2014 Connor Abbott
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Connor Abbott ([email protected])
+ *
+ */
+
+#include "nir.h"
+
+nir_const_value nir_eval_const_opcode(nir_op op, unsigned num_components,
+                                      nir_const_value *src);