glsl: move to compiler/

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Acked-by: Matt Turner <mattst88@gmail.com>
Acked-by: Jose Fonseca <jfonseca@vmware.com>

1 files changed, 488 insertions, 0 deletions

diff --git a/src/compiler/glsl/opt_minmax.cpp b/src/compiler/glsl/opt_minmax.cpp
new file mode 100644
index 0000000..29482ee
--- /dev/null
+++ b/src/compiler/glsl/opt_minmax.cpp
@@ -0,0 +1,488 @@
+/*
+ * 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.
+ */
+
+/**
+ * \file opt_minmax.cpp
+ *
+ * Drop operands from an expression tree of only min/max operations if they
+ * can be proven to not contribute to the final result.
+ *
+ * The algorithm is similar to alpha-beta pruning on a minmax search.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_optimization.h"
+#include "ir_builder.h"
+#include "program/prog_instruction.h"
+#include "compiler/glsl_types.h"
+#include "main/macros.h"
+
+using namespace ir_builder;
+
+namespace {
+
+enum compare_components_result {
+   LESS,
+   LESS_OR_EQUAL,
+   EQUAL,
+   GREATER_OR_EQUAL,
+   GREATER,
+   MIXED
+};
+
+class minmax_range {
+public:
+   minmax_range(ir_constant *low = NULL, ir_constant *high = NULL)
+   {
+      this->low = low;
+      this->high = high;
+   }
+
+   /* low is the lower limit of the range, high is the higher limit. NULL on
+    * low means negative infinity (unlimited) and on high positive infinity
+    * (unlimited). Because of the two interpretations of the value NULL,
+    * arbitrary comparison between ir_constants is impossible.
+    */
+   ir_constant *low;
+   ir_constant *high;
+};
+
+class ir_minmax_visitor : public ir_rvalue_enter_visitor {
+public:
+   ir_minmax_visitor()
+      : progress(false)
+   {
+   }
+
+   ir_rvalue *prune_expression(ir_expression *expr, minmax_range baserange);
+
+   void handle_rvalue(ir_rvalue **rvalue);
+
+   bool progress;
+};
+
+/*
+ * Returns LESS if all vector components of `a' are strictly lower than of `b',
+ * GREATER if all vector components of `a' are strictly greater than of `b',
+ * MIXED if some vector components of `a' are strictly lower than of `b' while
+ * others are strictly greater, or EQUAL otherwise.
+ */
+static enum compare_components_result
+compare_components(ir_constant *a, ir_constant *b)
+{
+   assert(a != NULL);
+   assert(b != NULL);
+
+   assert(a->type->base_type == b->type->base_type);
+
+   unsigned a_inc = a->type->is_scalar() ? 0 : 1;
+   unsigned b_inc = b->type->is_scalar() ? 0 : 1;
+   unsigned components = MAX2(a->type->components(), b->type->components());
+
+   bool foundless = false;
+   bool foundgreater = false;
+   bool foundequal = false;
+
+   for (unsigned i = 0, c0 = 0, c1 = 0;
+        i < components;
+        c0 += a_inc, c1 += b_inc, ++i) {
+      switch (a->type->base_type) {
+      case GLSL_TYPE_UINT:
+         if (a->value.u[c0] < b->value.u[c1])
+            foundless = true;
+         else if (a->value.u[c0] > b->value.u[c1])
+            foundgreater = true;
+         else
+            foundequal = true;
+         break;
+      case GLSL_TYPE_INT:
+         if (a->value.i[c0] < b->value.i[c1])
+            foundless = true;
+         else if (a->value.i[c0] > b->value.i[c1])
+            foundgreater = true;
+         else
+            foundequal = true;
+         break;
+      case GLSL_TYPE_FLOAT:
+         if (a->value.f[c0] < b->value.f[c1])
+            foundless = true;
+         else if (a->value.f[c0] > b->value.f[c1])
+            foundgreater = true;
+         else
+            foundequal = true;
+         break;
+      case GLSL_TYPE_DOUBLE:
+         if (a->value.d[c0] < b->value.d[c1])
+            foundless = true;
+         else if (a->value.d[c0] > b->value.d[c1])
+            foundgreater = true;
+         else
+            foundequal = true;
+         break;
+      default:
+         unreachable("not reached");
+      }
+   }
+
+   if (foundless && foundgreater) {
+      /* Some components are strictly lower, others are strictly greater */
+      return MIXED;
+   }
+
+   if (foundequal) {
+       /* It is not mixed, but it is not strictly lower or greater */
+      if (foundless)
+         return LESS_OR_EQUAL;
+      if (foundgreater)
+         return GREATER_OR_EQUAL;
+      return EQUAL;
+   }
+
+   /* All components are strictly lower or strictly greater */
+   return foundless ? LESS : GREATER;
+}
+
+static ir_constant *
+combine_constant(bool ismin, ir_constant *a, ir_constant *b)
+{
+   void *mem_ctx = ralloc_parent(a);
+   ir_constant *c = a->clone(mem_ctx, NULL);
+   for (unsigned i = 0; i < c->type->components(); i++) {
+      switch (c->type->base_type) {
+      case GLSL_TYPE_UINT:
+         if ((ismin && b->value.u[i] < c->value.u[i]) ||
+             (!ismin && b->value.u[i] > c->value.u[i]))
+            c->value.u[i] = b->value.u[i];
+         break;
+      case GLSL_TYPE_INT:
+         if ((ismin && b->value.i[i] < c->value.i[i]) ||
+             (!ismin && b->value.i[i] > c->value.i[i]))
+            c->value.i[i] = b->value.i[i];
+         break;
+      case GLSL_TYPE_FLOAT:
+         if ((ismin && b->value.f[i] < c->value.f[i]) ||
+             (!ismin && b->value.f[i] > c->value.f[i]))
+            c->value.f[i] = b->value.f[i];
+         break;
+      case GLSL_TYPE_DOUBLE:
+         if ((ismin && b->value.d[i] < c->value.d[i]) ||
+             (!ismin && b->value.d[i] > c->value.d[i]))
+            c->value.d[i] = b->value.d[i];
+         break;
+      default:
+         assert(!"not reached");
+      }
+   }
+   return c;
+}
+
+static ir_constant *
+smaller_constant(ir_constant *a, ir_constant *b)
+{
+   assert(a != NULL);
+   assert(b != NULL);
+
+   enum compare_components_result ret = compare_components(a, b);
+   if (ret == MIXED)
+      return combine_constant(true, a, b);
+   else if (ret < EQUAL)
+      return a;
+   else
+      return b;
+}
+
+static ir_constant *
+larger_constant(ir_constant *a, ir_constant *b)
+{
+   assert(a != NULL);
+   assert(b != NULL);
+
+   enum compare_components_result ret = compare_components(a, b);
+   if (ret == MIXED)
+      return combine_constant(false, a, b);
+   else if (ret < EQUAL)
+      return b;
+   else
+      return a;
+}
+
+/* Combines two ranges by doing an element-wise min() / max() depending on the
+ * operation.
+ */
+static minmax_range
+combine_range(minmax_range r0, minmax_range r1, bool ismin)
+{
+   minmax_range ret;
+
+   if (!r0.low) {
+      ret.low = ismin ? r0.low : r1.low;
+   } else if (!r1.low) {
+      ret.low = ismin ? r1.low : r0.low;
+   } else {
+      ret.low = ismin ? smaller_constant(r0.low, r1.low) :
+         larger_constant(r0.low, r1.low);
+   }
+
+   if (!r0.high) {
+      ret.high = ismin ? r1.high : r0.high;
+   } else if (!r1.high) {
+      ret.high = ismin ? r0.high : r1.high;
+   } else {
+      ret.high = ismin ? smaller_constant(r0.high, r1.high) :
+         larger_constant(r0.high, r1.high);
+   }
+
+   return ret;
+}
+
+/* Returns a range so that lower limit is the larger of the two lower limits,
+ * and higher limit is the smaller of the two higher limits.
+ */
+static minmax_range
+range_intersection(minmax_range r0, minmax_range r1)
+{
+   minmax_range ret;
+
+   if (!r0.low)
+      ret.low = r1.low;
+   else if (!r1.low)
+      ret.low = r0.low;
+   else
+      ret.low = larger_constant(r0.low, r1.low);
+
+   if (!r0.high)
+      ret.high = r1.high;
+   else if (!r1.high)
+      ret.high = r0.high;
+   else
+      ret.high = smaller_constant(r0.high, r1.high);
+
+   return ret;
+}
+
+static minmax_range
+get_range(ir_rvalue *rval)
+{
+   ir_expression *expr = rval->as_expression();
+   if (expr && (expr->operation == ir_binop_min ||
+                expr->operation == ir_binop_max)) {
+      minmax_range r0 = get_range(expr->operands[0]);
+      minmax_range r1 = get_range(expr->operands[1]);
+      return combine_range(r0, r1, expr->operation == ir_binop_min);
+   }
+
+   ir_constant *c = rval->as_constant();
+   if (c) {
+      return minmax_range(c, c);
+   }
+
+   return minmax_range();
+}
+
+/**
+ * Prunes a min/max expression considering the base range of the parent
+ * min/max expression.
+ *
+ * @param baserange the range that the parents of this min/max expression
+ * in the min/max tree will clamp its value to.
+ */
+ir_rvalue *
+ir_minmax_visitor::prune_expression(ir_expression *expr, minmax_range baserange)
+{
+   assert(expr->operation == ir_binop_min ||
+          expr->operation == ir_binop_max);
+
+   bool ismin = expr->operation == ir_binop_min;
+   minmax_range limits[2];
+
+   /* Recurse to get the ranges for each of the subtrees of this
+    * expression. We need to do this as a separate step because we need to
+    * know the ranges of each of the subtrees before we prune either one.
+    * Consider something like this:
+    *
+    *        max
+    *     /       \
+    *    max     max
+    *   /   \   /   \
+    *  3    a   b    2
+    *
+    * We would like to prune away the max on the bottom-right, but to do so
+    * we need to know the range of the expression on the left beforehand,
+    * and there's no guarantee that we will visit either subtree in a
+    * particular order.
+    */
+   for (unsigned i = 0; i < 2; ++i)
+      limits[i] = get_range(expr->operands[i]);
+
+   for (unsigned i = 0; i < 2; ++i) {
+      bool is_redundant = false;
+
+      enum compare_components_result cr = LESS;
+      if (ismin) {
+         /* If this operand will always be greater than the other one, it's
+          * redundant.
+          */
+         if (limits[i].low && limits[1 - i].high) {
+               cr = compare_components(limits[i].low, limits[1 - i].high);
+            if (cr >= EQUAL && cr != MIXED)
+               is_redundant = true;
+         }
+         /* If this operand is always greater than baserange, then even if
+          * it's smaller than the other one it'll get clamped, so it's
+          * redundant.
+          */
+         if (!is_redundant && limits[i].low && baserange.high) {
+            cr = compare_components(limits[i].low, baserange.high);
+            if (cr >= EQUAL && cr != MIXED)
+               is_redundant = true;
+         }
+      } else {
+         /* If this operand will always be lower than the other one, it's
+          * redundant.
+          */
+         if (limits[i].high && limits[1 - i].low) {
+            cr = compare_components(limits[i].high, limits[1 - i].low);
+            if (cr <= EQUAL)
+               is_redundant = true;
+         }
+         /* If this operand is always lower than baserange, then even if
+          * it's greater than the other one it'll get clamped, so it's
+          * redundant.
+          */
+         if (!is_redundant && limits[i].high && baserange.low) {
+            cr = compare_components(limits[i].high, baserange.low);
+            if (cr <= EQUAL)
+               is_redundant = true;
+         }
+      }
+
+      if (is_redundant) {
+         progress = true;
+
+         /* Recurse if necessary. */
+         ir_expression *op_expr = expr->operands[1 - i]->as_expression();
+         if (op_expr && (op_expr->operation == ir_binop_min ||
+                         op_expr->operation == ir_binop_max)) {
+            return prune_expression(op_expr, baserange);
+         }
+
+         return expr->operands[1 - i];
+      } else if (cr == MIXED) {
+         /* If we have mixed vector operands, we can try to resolve the minmax
+          * expression by doing a component-wise minmax:
+          *
+          *             min                          min
+          *           /    \                       /    \
+          *         min     a       ===>        [1,1]    a
+          *       /    \
+          *    [1,3]   [3,1]
+          *
+          */
+         ir_constant *a = expr->operands[0]->as_constant();
+         ir_constant *b = expr->operands[1]->as_constant();
+         if (a && b)
+            return combine_constant(ismin, a, b);
+      }
+   }
+
+   /* Now recurse to operands giving them the proper baserange. The baserange
+    * to pass is the intersection of our baserange and the other operand's
+    * limit with one of the ranges unlimited. If we can't compute a valid
+    * intersection, we use the current baserange.
+    */
+   for (unsigned i = 0; i < 2; ++i) {
+      ir_expression *op_expr = expr->operands[i]->as_expression();
+      if (op_expr && (op_expr->operation == ir_binop_min ||
+                      op_expr->operation == ir_binop_max)) {
+         /* We can only compute a new baserange for this operand if we managed
+          * to compute a valid range for the other operand.
+          */
+         if (ismin)
+            limits[1 - i].low = NULL;
+         else
+            limits[1 - i].high = NULL;
+         minmax_range base = range_intersection(limits[1 - i], baserange);
+         expr->operands[i] = prune_expression(op_expr, base);
+      }
+   }
+
+   /* If we got here we could not discard any of the operands of the minmax
+    * expression, but we can still try to resolve the expression if both
+    * operands are constant. We do this after the loop above, to make sure
+    * that if our operands are minmax expressions we have tried to prune them
+    * first (hopefully reducing them to constants).
+    */
+   ir_constant *a = expr->operands[0]->as_constant();
+   ir_constant *b = expr->operands[1]->as_constant();
+   if (a && b)
+      return combine_constant(ismin, a, b);
+
+   return expr;
+}
+
+static ir_rvalue *
+swizzle_if_required(ir_expression *expr, ir_rvalue *rval)
+{
+   if (expr->type->is_vector() && rval->type->is_scalar()) {
+      return swizzle(rval, SWIZZLE_XXXX, expr->type->vector_elements);
+   } else {
+      return rval;
+   }
+}
+
+void
+ir_minmax_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+   if (!*rvalue)
+      return;
+
+   ir_expression *expr = (*rvalue)->as_expression();
+   if (!expr || (expr->operation != ir_binop_min &&
+                 expr->operation != ir_binop_max))
+      return;
+
+   ir_rvalue *new_rvalue = prune_expression(expr, minmax_range());
+   if (new_rvalue == *rvalue)
+      return;
+
+   /* If the expression type is a vector and the optimization leaves a scalar
+    * as the result, we need to turn it into a vector.
+    */
+   *rvalue = swizzle_if_required(expr, new_rvalue);
+
+   progress = true;
+}
+
+}
+
+bool
+do_minmax_prune(exec_list *instructions)
+{
+   ir_minmax_visitor v;
+
+   visit_list_elements(&v, instructions);
+
+   return v.progress;
+}