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Commit 89bc8ff4 authored by Marcin Ślusarz's avatar Marcin Ślusarz Committed by Marge Bot
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glsl/opt_algebraic: disable invalid optimization

When operators other than eq and ne are involved we can't really
move operands around and negate them because such transformation
may change the value of the whole expression.

Some examples:

For unsigned var:
0 >= 1u + var would eventually become 0xffffffff >= var,
which would always evaluate to true, when original expression
was true only for var == 0xffffffff.

For signed var:
0 >= 1 + var would become -1 >= var, which would evaluate to
false for var == 2147483647, when original expression evaluated
to true (because signed overflow is defined to wrap around in
glsl, 1 + 2147483647 == -2147483648, so 0 >= -2147483648).

Closes: mesa/mesa#5226


Fixes: 34ec1a24 ("glsl: Optimize (x + y cmp 0) into (x cmp -y).")
Signed-off-by: default avatarMarcin Ślusarz <marcin.slusarz@intel.com>
Reviewed-by: default avatarAlyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: default avatarIan Romanick <ian.d.romanick@intel.com>
Part-of: <mesa/mesa!12359>
parent f9e3ae6a
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......@@ -708,8 +708,6 @@ ir_algebraic_visitor::handle_expression(ir_expression *ir)
}
break;
case ir_binop_less:
case ir_binop_gequal:
case ir_binop_equal:
case ir_binop_nequal:
for (int add_pos = 0; add_pos < 2; add_pos++) {
......
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