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glsl: In ir_set_program_inouts, handle indexing outside array/matrix bounds.

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According to GLSL, indexing into an array or matrix with an
out-of-range constant results in a compile error.  However, indexing
with an out-of-range value that isn't constant merely results in
undefined results.

Since optimization passes (e.g. loop unrolling) can convert
non-constant array indices into constant array indices, it's possible
that ir_set_program_inouts will encounter a constant array index that
is out of range; if this happens, just mark the whole array as used.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Paul Berry 2013-07-31 11:25:13 -07:00
parent 1c789d8087
commit cea946e39d
1 changed files with 26 additions and 5 deletions
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31
src/glsl/ir_set_program_inouts.cpp
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@ -171,13 +171,34 @@ ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable *var,
if (!index_as_constant)
return false;
int width = 1;
if (type->is_array() && type->fields.array->is_matrix()) {
width = type->fields.array->matrix_columns;
unsigned elem_width;
unsigned num_elems;
if (type->is_array()) {
num_elems = type->length;
if (type->fields.array->is_matrix())
elem_width = type->fields.array->matrix_columns;
else
elem_width = 1;
} else {
num_elems = type->matrix_columns;
elem_width = 1;
}
mark(this->prog, var, index_as_constant->value.u[0] * width, width,
this->shader_type == GL_FRAGMENT_SHADER);
if (index_as_constant->value.u[0] >= num_elems) {
/* Constant index outside the bounds of the matrix/array. This could
* arise as a result of constant folding of a legal GLSL program.
*
* Even though the spec says that indexing outside the bounds of a
* matrix/array results in undefined behaviour, we don't want to pass
* out-of-range values to mark() (since this could result in slots that
* don't exist being marked as used), so just let the caller mark the
* whole variable as used.
*/
return false;
}
mark(this->prog, var, index_as_constant->value.u[0] * elem_width,
elem_width, this->shader_type == GL_FRAGMENT_SHADER);
return true;
}