[Mesa-dev] [PATCH 08/22] glsl: Add abs to get_range

[Thomas Helland]

v2: Set in alphabetic order
    Change to use the new IS_CONSTANT macro
    Add a function for creating a minmax_range from two constants
    Use the function to improve the resolution of abs's range.
---
 src/glsl/opt_minmax.cpp | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/glsl/opt_minmax.cpp b/src/glsl/opt_minmax.cpp
index 8fee0aa..04ae0c0 100644
--- a/src/glsl/opt_minmax.cpp
+++ b/src/glsl/opt_minmax.cpp
@@ -213,6 +213,21 @@ larger_constant(ir_constant *a, ir_constant *b)
       return a;
 }
 
+/* Makes a minmax_range from the two constants
+ * The smaller of them is set as low, and the larger as high.
+ * If the comparison between the two is mixed the two will be combined
+ * in larger_constant and smaller_constant to yield a correct result.
+ */
+static minmax_range
+make_range_from_constants(ir_constant *a, ir_constant *b)
+{
+   assert(a != NULL);
+   assert(b != NULL);
+
+   return minmax_range(smaller_constant(a, b),
+                       larger_constant(a, b));
+}
+
 /* Combines two ranges by doing an element-wise min() / max() depending on the
  * operation.
  */
@@ -282,6 +297,19 @@ get_range(ir_rvalue *rval)
    if (expr) {
       switch (expr->operation) {
 
+      case ir_unop_abs:
+         r0 = get_range(expr->operands[0]);
+
+         if (r0.high && r0.low)
+            return make_range_from_constants(
+                      abs(r0.high)->constant_expression_value(),
+                      abs(r0.low)->constant_expression_value());
+
+         if (IS_CONSTANT(r0.low, >, 0.0f))
+            return minmax_range(r0.low, NULL);
+
+         return minmax_range(new(mem_ctx) ir_constant(0.0f), NULL);
+
       case ir_unop_exp:
       case ir_unop_exp2:
       case ir_unop_sqrt:
-- 
2.2.1