Module: Mesa Branch: master Commit: 44a86e2b4fca7c7cab243dfa62dc17f4379fc8e3 URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=44a86e2b4fca7c7cab243dfa62dc17f4379fc8e3
Author: Kenneth Graunke <kenn...@whitecape.org> Date: Fri Jan 24 10:47:49 2014 -0800 glsl: Fix chained assignments of vector channels. Simple shaders such as: void splat(vec2 v, float f) { v[0] = v[1] = f; } failed to compile with the following error: error: value of type vec2 cannot be assigned to variable of type float First, we would process v[1] = f, and transform: LHS: (expression float vector_extract (var_ref v) (constant int (1))) RHS: (var_ref f) into: LHS: (var_ref v) RHS: (expression vec2 vector_insert (var_ref v) (constant int (1)) (var_ref f)) Note that the LHS type is now vec2, not a float. This is surprising, but not the real problem. After emitting assignments, this ultimately becomes: (declare (temporary) vec2 assignment_tmp) (assign (xy) (var_ref assignment_tmp) (expression vec2 vector_insert (var_ref v) (constant int (1)) (var_ref f))) (assign (xy) (var_ref v) (var_ref assignment_tmp)) We would then return (var_ref assignment_tmp) as the rvalue, which has the wrong type---it should be float, but is instead a vec2. To fix this, we simply return (vector_extract (var_ref assignment_temp) <the appropriate channel>) to pull out the desired float value. Fixes Piglit's chained-assignment-with-vector-constant-index.vert and chained-assignment-with-vector-dynamic-index.vert tests. Cc: mesa-sta...@lists.freedesktop.org Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=74026 Reported-by: Dan Ginsburg <d...@valvesoftware.com> Reviewed-by: Ian Romanick <ian.d.roman...@intel.com> Reviewed-by: Matt Turner <matts...@gmail.com> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org> --- src/glsl/ast_to_hir.cpp | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp index 67ab09b..1bfb4e5 100644 --- a/src/glsl/ast_to_hir.cpp +++ b/src/glsl/ast_to_hir.cpp @@ -740,6 +740,7 @@ do_assignment(exec_list *instructions, struct _mesa_glsl_parse_state *state, { void *ctx = state; bool error_emitted = (lhs->type->is_error() || rhs->type->is_error()); + ir_rvalue *extract_channel = NULL; /* If the assignment LHS comes back as an ir_binop_vector_extract * expression, move it to the RHS as an ir_triop_vector_insert. @@ -755,11 +756,23 @@ do_assignment(exec_list *instructions, struct _mesa_glsl_parse_state *state, if (new_rhs == NULL) { return lhs; } else { + /* This converts: + * - LHS: (expression float vector_extract <vec> <channel>) + * - RHS: <scalar> + * into: + * - LHS: <vec> + * - RHS: (expression vec2 vector_insert <vec> <channel> <scalar>) + * + * The LHS type is now a vector instead of a scalar. Since GLSL + * allows assignments to be used as rvalues, we need to re-extract + * the channel from assignment_temp when returning the rvalue. + */ + extract_channel = lhs_expr->operands[1]; rhs = new(ctx) ir_expression(ir_triop_vector_insert, lhs_expr->operands[0]->type, lhs_expr->operands[0], new_rhs, - lhs_expr->operands[1]); + extract_channel); lhs = lhs_expr->operands[0]->clone(ctx, NULL); } } @@ -856,6 +869,11 @@ do_assignment(exec_list *instructions, struct _mesa_glsl_parse_state *state, if (!error_emitted) instructions->push_tail(new(ctx) ir_assignment(lhs, deref_var)); + if (extract_channel) { + return new(ctx) ir_expression(ir_binop_vector_extract, + new(ctx) ir_dereference_variable(var), + extract_channel->clone(ctx, NULL)); + } return new(ctx) ir_dereference_variable(var); } _______________________________________________ mesa-commit mailing list mesa-commit@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-commit