nir/algebraic: support for power-of-two optimizations

Some optimizations, like converting integer multiply/divide into left/
right shifts, have additional constraints on the search expression.
Like requiring that a variable is a constant power of two.  Support
these cases by allowing a fxn name to be appended to the search var
expression (ie. "a#32(is_power_of_two)").

Signed-off-by: Rob Clark <robclark@freedesktop.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

1 files changed, 94 insertions, 0 deletions

diff --git a/src/compiler/nir/nir_search_helpers.h b/src/compiler/nir/nir_search_helpers.h
new file mode 100644
index 0000000..5037944
--- /dev/null
+++ b/src/compiler/nir/nir_search_helpers.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright © 2016 Red Hat
+ *
+ * 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:
+ *    Rob Clark <robclark@freedesktop.org>
+ */
+
+#ifndef _NIR_SEARCH_HELPERS_
+#define _NIR_SEARCH_HELPERS_
+
+#include "nir.h"
+
+static inline bool
+__is_power_of_two(unsigned int x)
+{
+   return ((x != 0) && !(x & (x - 1)));
+}
+
+static inline bool
+is_pos_power_of_two(nir_alu_instr *instr, unsigned src, unsigned num_components,
+                    const uint8_t *swizzle)
+{
+   nir_const_value *val = nir_src_as_const_value(instr->src[src].src);
+
+   /* only constant src's: */
+   if (!val)
+      return false;
+
+   for (unsigned i = 0; i < num_components; i++) {
+      switch (nir_op_infos[instr->op].input_types[src]) {
+      case nir_type_int:
+         if (val->i32[swizzle[i]] < 0)
+            return false;
+         if (!__is_power_of_two(val->i32[swizzle[i]]))
+            return false;
+         break;
+      case nir_type_uint:
+         if (!__is_power_of_two(val->u32[swizzle[i]]))
+            return false;
+         break;
+      default:
+         return false;
+      }
+   }
+
+   return true;
+}
+
+static inline bool
+is_neg_power_of_two(nir_alu_instr *instr, unsigned src, unsigned num_components,
+                    const uint8_t *swizzle)
+{
+   nir_const_value *val = nir_src_as_const_value(instr->src[src].src);
+
+   /* only constant src's: */
+   if (!val)
+      return false;
+
+   for (unsigned i = 0; i < num_components; i++) {
+      switch (nir_op_infos[instr->op].input_types[src]) {
+      case nir_type_int:
+         if (val->i32[swizzle[i]] > 0)
+            return false;
+         if (!__is_power_of_two(abs(val->i32[swizzle[i]])))
+            return false;
+         break;
+      default:
+         return false;
+      }
+   }
+
+   return true;
+}
+
+#endif /* _NIR_SEARCH_ */