Mesa (master): glsl: Rewrite and fix min/max to saturate optimization.
Matt Turner
mattst88 at kemper.freedesktop.org
Wed Feb 25 16:44:53 UTC 2015
Module: Mesa
Branch: master
Commit: cb25087c7bd5f1ad2515647278b32d3f07803f77
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=cb25087c7bd5f1ad2515647278b32d3f07803f77
Author: Matt Turner <mattst88 at gmail.com>
Date: Tue Feb 24 10:41:52 2015 -0800
glsl: Rewrite and fix min/max to saturate optimization.
There were some bugs, and the code was really difficult to follow. We
would optimize
min(max(x, b), 1.0) into max(sat(x), b)
but not pay attention to the order of min/max and also do
max(min(x, b), 1.0) into max(sat(x), b)
Corrects four shaders from Champions of Regnum that do
min(max(x, 1), 10)
and corrects rendering of Mass Effect under VMware Workstation.
Cc: "10.4 10.5" <mesa-stable at lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89180
Reviewed-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
---
src/glsl/opt_algebraic.cpp | 75 +++++++++++++++++++++++++++-----------------
1 file changed, 46 insertions(+), 29 deletions(-)
diff --git a/src/glsl/opt_algebraic.cpp b/src/glsl/opt_algebraic.cpp
index 6784242..c3f3842 100644
--- a/src/glsl/opt_algebraic.cpp
+++ b/src/glsl/opt_algebraic.cpp
@@ -744,48 +744,65 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
* a saturate operation
*/
for (int op = 0; op < 2; op++) {
- ir_expression *minmax = op_expr[op];
+ ir_expression *inner_expr = op_expr[op];
ir_constant *outer_const = op_const[1 - op];
ir_expression_operation op_cond = (ir->operation == ir_binop_max) ?
ir_binop_min : ir_binop_max;
- if (!minmax || !outer_const || (minmax->operation != op_cond))
+ if (!inner_expr || !outer_const || (inner_expr->operation != op_cond))
continue;
+ /* One of these has to be a constant */
+ if (!inner_expr->operands[0]->as_constant() &&
+ !inner_expr->operands[1]->as_constant())
+ break;
+
/* Found a min(max) combination. Now try to see if its operands
* meet our conditions that we can do just a single saturate operation
*/
for (int minmax_op = 0; minmax_op < 2; minmax_op++) {
- ir_rvalue *inner_val_a = minmax->operands[minmax_op];
- ir_rvalue *inner_val_b = minmax->operands[1 - minmax_op];
+ ir_rvalue *x = inner_expr->operands[minmax_op];
+ ir_rvalue *y = inner_expr->operands[1 - minmax_op];
- if (!inner_val_a || !inner_val_b)
+ ir_constant *inner_const = y->as_constant();
+ if (!inner_const)
continue;
- /* Found a {min|max} ({max|min} (x, 0.0), 1.0) operation and its variations */
- if ((outer_const->is_one() && inner_val_a->is_zero()) ||
- (inner_val_a->is_one() && outer_const->is_zero()))
- return saturate(inner_val_b);
-
- /* Found a {min|max} ({max|min} (x, 0.0), b) where b < 1.0
- * and its variations
- */
- if (is_less_than_one(outer_const) && inner_val_b->is_zero())
- return expr(ir_binop_min, saturate(inner_val_a), outer_const);
-
- if (!inner_val_b->as_constant())
- continue;
-
- if (is_less_than_one(inner_val_b->as_constant()) && outer_const->is_zero())
- return expr(ir_binop_min, saturate(inner_val_a), inner_val_b);
-
- /* Found a {min|max} ({max|min} (x, b), 1.0), where b > 0.0
- * and its variations
- */
- if (outer_const->is_one() && is_greater_than_zero(inner_val_b->as_constant()))
- return expr(ir_binop_max, saturate(inner_val_a), inner_val_b);
- if (inner_val_b->as_constant()->is_one() && is_greater_than_zero(outer_const))
- return expr(ir_binop_max, saturate(inner_val_a), outer_const);
+ /* min(max(x, 0.0), 1.0) is sat(x) */
+ if (ir->operation == ir_binop_min &&
+ inner_const->is_zero() &&
+ outer_const->is_one())
+ return saturate(x);
+
+ /* max(min(x, 1.0), 0.0) is sat(x) */
+ if (ir->operation == ir_binop_max &&
+ inner_const->is_one() &&
+ outer_const->is_zero())
+ return saturate(x);
+
+ /* min(max(x, 0.0), b) where b < 1.0 is sat(min(x, b)) */
+ if (ir->operation == ir_binop_min &&
+ inner_const->is_zero() &&
+ is_less_than_one(outer_const))
+ return saturate(expr(ir_binop_min, x, outer_const));
+
+ /* max(min(x, b), 0.0) where b < 1.0 is sat(min(x, b)) */
+ if (ir->operation == ir_binop_max &&
+ is_less_than_one(inner_const) &&
+ outer_const->is_zero())
+ return saturate(expr(ir_binop_min, x, inner_const));
+
+ /* max(min(x, 1.0), b) where b > 0.0 is sat(max(x, b)) */
+ if (ir->operation == ir_binop_max &&
+ inner_const->is_one() &&
+ is_greater_than_zero(outer_const))
+ return saturate(expr(ir_binop_max, x, outer_const));
+
+ /* min(max(x, b), 1.0) where b > 0.0 is sat(max(x, b)) */
+ if (ir->operation == ir_binop_min &&
+ is_greater_than_zero(inner_const) &&
+ outer_const->is_one())
+ return saturate(expr(ir_binop_max, x, inner_const));
}
}
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