[Mesa-dev] [PATCH 17/22] glsl: Add log and log2 to get_range

[Thomas Helland]

The spec states that log / log2 of x <= 0 is undefined.
Just set the range to 0 if this is the case.

Also set the range according to how we are oriented
around one, as this causes us to shift from positive to
negative values.

V2: Utilize the new IS_CONSTANT() macro
    Put in alphabetic order
---
 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 5515f51..0901c95 100644
--- a/src/glsl/opt_minmax.cpp
+++ b/src/glsl/opt_minmax.cpp
@@ -356,6 +356,23 @@ get_range(ir_rvalue *rval)
 
          return minmax_range(new(mem_ctx) ir_constant(0.0f), NULL);
 
+      case ir_unop_log:
+      case ir_unop_log2:
+         r0 = get_range(expr->operands[0]);
+
+         // Result is undefined, so we can set the range to whatever
+         if (IS_CONSTANT(r0.high, <=, 0.0f))
+            return minmax_range(new(mem_ctx) ir_constant(0.0f),
+                                new(mem_ctx) ir_constant(0.0f));
+
+         if (IS_CONSTANT(r0.low, >=, 1.0f))
+            low = new(mem_ctx) ir_constant(0.0f);
+
+         if (IS_CONSTANT(r0.high, <=, 1.0f))
+            high = new(mem_ctx) ir_constant(0.0f);
+
+         return minmax_range(low, high);
+
       case ir_unop_exp:
       case ir_unop_exp2:
       case ir_unop_sqrt:
-- 
2.2.1