nir: Add an expression matching framework

This framework provides a simple way to do simple search-and-replace
operations on NIR code.  The nir_search.h header provides four simple data
structures for representing expressions:  nir_value and four subtypes:
nir_variable, nir_constant, and nir_expression.  An expression tree can
then be represented by nesting these data structures as needed.  The
nir_replace_instr function takes an instruction, an expression, and a
value; if the instruction matches the expression, it is replaced with a new
chain of instructions to generate the given replacement value.  The
framework keeps track of swizzles on sources and automatically generates
the currect swizzles for the replacement value.

Reviewed-by: Connor Abbott <[email protected]>

1 files changed, 80 insertions, 0 deletions

diff --git a/src/glsl/nir/nir_search.h b/src/glsl/nir/nir_search.h
new file mode 100644
index 00000000000..8ec58b07139
--- /dev/null
+++ b/src/glsl/nir/nir_search.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright © 2014 Intel Corporation
+ *
+ * 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:
+ *    Jason Ekstrand ([email protected])
+ *
+ */
+
+#ifndef _NIR_SEARCH_
+#define _NIR_SEARCH_
+
+#include "nir.h"
+
+#define NIR_SEARCH_MAX_VARIABLES 16
+
+typedef enum {
+   nir_search_value_expression,
+   nir_search_value_variable,
+   nir_search_value_constant,
+} nir_search_value_type;
+
+typedef struct {
+   nir_search_value_type type;
+} nir_search_value;
+
+typedef struct {
+   nir_search_value value;
+
+   /** The variable index;  Must be less than NIR_SEARCH_MAX_VARIABLES */
+   unsigned variable;
+} nir_search_variable;
+
+typedef struct {
+   nir_search_value value;
+
+   union {
+      uint32_t u;
+      int32_t i;
+      float f;
+   } data;
+} nir_search_constant;
+
+typedef struct {
+   nir_search_value value;
+
+   nir_op opcode;
+   const nir_search_value *srcs[4];
+} nir_search_expression;
+
+NIR_DEFINE_CAST(nir_search_value_as_variable, nir_search_value,
+                nir_search_variable, value)
+NIR_DEFINE_CAST(nir_search_value_as_constant, nir_search_value,
+                nir_search_constant, value)
+NIR_DEFINE_CAST(nir_search_value_as_expression, nir_search_value,
+                nir_search_expression, value)
+
+nir_alu_instr *
+nir_replace_instr(nir_alu_instr *instr, const nir_search_expression *search,
+                  const nir_search_value *replace, void *mem_ctx);
+
+#endif /* _NIR_SEARCH_ */