Also handle undefined behaviour for sqrt(x) where x < 0
and rsq(x) where x <= 0.
This gives us some reduction in instruction count on some
Dungeon Defenders shaders as they are doing: max(exp(x), 0)
---
src/glsl/opt_minmax.cpp | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/src/glsl/opt_minmax.cpp b/src/glsl/opt_minmax.cpp
index a48d4d8..1aa4611 100644
--- a/src/glsl/opt_minmax.cpp
+++ b/src/glsl/opt_minmax.cpp
@@ -293,6 +293,23 @@ get_range(ir_rvalue *rval)
high = larger_constant(r0.high,
abs(r0.low)->constant_expression_value());
return minmax_range(low, high);
+ case ir_unop_sqrt:
+ case ir_unop_rsq:
+ case ir_unop_exp:
+ case ir_unop_exp2:
+ r0 = get_range(expr->operands[0]);
+ if (expr->operation == ir_unop_sqrt &&
+ is_less_than_zero(r0.high))
+ high = new(mem_ctx) ir_constant(0.0f);
+ if (expr->operation == ir_unop_rsq &&
+ is_less_than_or_equal_zero(r0.high))
+ high = new(mem_ctx) ir_constant(0.0f);
+ /* TODO: If we know, i.e, the lower range of the operand
+ * we can calculate the lower range
+ */
+ low = new(mem_ctx) ir_constant(0.0f);
+ return minmax_range(low, NULL);
+
case ir_unop_sin:
case ir_unop_sin_reduced:
case ir_unop_cos:
--
2.0.3
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