[Mesa-dev] [PATCH] glsl: fix constructing a vector from a matrix
Martin Peres
martin.peres at linux.intel.com
Tue May 26 05:32:21 PDT 2015
Without this patch, the following constructs (not an extensive list)
would crash mesa:
- mat2 foo = mat2(1); vec4 bar = vec4(foo);
- mat3 foo = mat3(1); vec4 bar = vec4(foo);
- mat3 foo = mat3(1); ivec4 bar = ivec4(foo);
The first case is explicitely allowed by the GLSL spec, as seen on
page 101 of the GLSL 4.40 spec:
"vec4(mat2) // the vec4 is column 0 followed by column 1"
The other cases are implicitely allowed also.
The actual changes are quite minimal. We first split each column of
the matrix to a list of vectors and then use them to initialize the
vector. An additional check to make sure that we are not trying to
copy 0 elements of a vector fix the (i)vec4(mat3) case as the last
vector (3rd column) is not needed at all.
Signed-off-by: Martin Peres <martin.peres at linux.intel.com>
---
src/glsl/ast_function.cpp | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 1e77124..92e26bf 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -993,11 +993,15 @@ emit_inline_vector_constructor(const glsl_type *type,
ir_variable *var = new(ctx) ir_variable(type, "vec_ctor", ir_var_temporary);
instructions->push_tail(var);
- /* There are two kinds of vector constructors.
+ /* There are three kinds of vector constructors.
*
* - Construct a vector from a single scalar by replicating that scalar to
* all components of the vector.
*
+ * - Construct a vector from at least a matrix. This case should already
+ * have been taken care of in ast_function_expression::hir by breaking
+ * down the matrix into a series of column vectors.
+ *
* - Construct a vector from an arbirary combination of vectors and
* scalars. The components of the constructor parameters are assigned
* to the vector in order until the vector is full.
@@ -1091,6 +1095,14 @@ emit_inline_vector_constructor(const glsl_type *type,
rhs_components = lhs_components - base_component;
}
+ /* If we do not have any components left to copy, break out of the
+ * loop. This can happen when initializing a vec4 with a mat3 as the
+ * mat3 would have been broken into a series of column vectors.
+ */
+ if (rhs_components == 0) {
+ break;
+ }
+
const ir_constant *const c = param->as_constant();
if (c == NULL) {
/* Mask of fields to be written in the assignment.
@@ -1681,11 +1693,11 @@ ast_function_expression::hir(exec_list *instructions,
return ir_rvalue::error_value(ctx);
}
- /* Later, we cast each parameter to the same base type as the
- * constructor. Since there are no non-floating point matrices, we
- * need to break them up into a series of column vectors.
+ /* Matrices can never be consumed as is by any constructor but matrix
+ * constructors. If the constructor type is not matrix, always break the
+ * matrix up into a series of column vectors.
*/
- if (constructor_type->base_type != GLSL_TYPE_FLOAT) {
+ if (!constructor_type->is_matrix()) {
foreach_in_list_safe(ir_rvalue, matrix, &actual_parameters) {
if (!matrix->type->is_matrix())
continue;
--
2.4.1
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