glsl: fix opt_minmax redundancy checks against baserange

Marking operations as redundant if they are equal to the base
range is fine when the tree structure is something like this:

        max
      /     \
     max     b
    /   \
   3    max
       /   \
      3     a

But the opt falls apart with a tree like this:

        max
     /       \
    max     max
   /   \   /   \
  3    a   b    3

The problem is that both branches are treated the same: descending in
the left branch will prune the constant, and then descending the right
branch will prune the constant there as well, because limits[0] wasn't
updated to take the change on the left branch into account, and so we
still get [3,\infty) as baserange.

In order to fix the bug we just disable the marking of redundant expressions
when they match the baserange.

NIR algebraic opt will clean up the first tree for anyway, hopefully
other backends are smart enough to do this also.

Cc: "13.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

diff --git a/src/compiler/glsl/opt_minmax.cpp b/src/compiler/glsl/opt_minmax.cpp
index 29482ee69de2e1b2806a6e84c0c28deb9246cf45..9f64db9c07e00b5f232f711bd7bc2a300f1b949d 100644 (file)
--- a/src/compiler/glsl/opt_minmax.cpp
+++ b/src/compiler/glsl/opt_minmax.cpp
@@ -355,7 +355,7 @@ ir_minmax_visitor::prune_expression(ir_expression *expr, minmax_range baserange)
           */
          if (!is_redundant && limits[i].low && baserange.high) {
             cr = compare_components(limits[i].low, baserange.high);
-            if (cr >= EQUAL && cr != MIXED)
+            if (cr > EQUAL && cr != MIXED)
                is_redundant = true;
          }
       } else {
@@ -373,7 +373,7 @@ ir_minmax_visitor::prune_expression(ir_expression *expr, minmax_range baserange)
           */
          if (!is_redundant && limits[i].high && baserange.low) {
             cr = compare_components(limits[i].high, baserange.low);
-            if (cr <= EQUAL)
+            if (cr < EQUAL)
                is_redundant = true;
          }
       }