From ca63a5ed3e9efb2bd645b425f7393089f4e132a6 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Nicolai=20H=C3=A4hnle?= Date: Tue, 1 Aug 2017 12:44:34 +0200 Subject: [PATCH] glsl: fix interpolateAtXxx(some_vec[idx], ...) with dynamic idx The dynamic index of a vector (not array!) is lowered to a sequence of conditional assignments. However, the interpolate_at_* expressions require that the interpolant is an l-value of a shader input. So instead of doing conditional assignments of parts of the shader input and then interpolating that (which is nonsensical), we interpolate the entire shader input and then do conditional assignments of the interpolated result. Reviewed-by: Timothy Arceri --- .../glsl/lower_vec_index_to_cond_assign.cpp | 31 ++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/src/compiler/glsl/lower_vec_index_to_cond_assign.cpp b/src/compiler/glsl/lower_vec_index_to_cond_assign.cpp index a26253998e0..89244266602 100644 --- a/src/compiler/glsl/lower_vec_index_to_cond_assign.cpp +++ b/src/compiler/glsl/lower_vec_index_to_cond_assign.cpp @@ -128,7 +128,36 @@ ir_vec_index_to_cond_assign_visitor::convert_vector_extract_to_cond_assign(ir_rv { ir_expression *const expr = ir->as_expression(); - if (expr == NULL || expr->operation != ir_binop_vector_extract) + if (expr == NULL) + return ir; + + if (expr->operation == ir_unop_interpolate_at_centroid || + expr->operation == ir_binop_interpolate_at_offset || + expr->operation == ir_binop_interpolate_at_sample) { + /* Lower interpolateAtXxx(some_vec[idx], ...) to + * interpolateAtXxx(some_vec, ...)[idx] before lowering to conditional + * assignments, to maintain the rule that the interpolant is an l-value + * referring to a (part of a) shader input. + * + * This is required when idx is dynamic (otherwise it gets lowered to + * a swizzle). + */ + ir_expression *const interpolant = expr->operands[0]->as_expression(); + if (!interpolant || interpolant->operation != ir_binop_vector_extract) + return ir; + + ir_rvalue *vec_input = interpolant->operands[0]; + ir_expression *const vec_interpolate = + new(base_ir) ir_expression(expr->operation, vec_input->type, + vec_input, expr->operands[1]); + + return convert_vec_index_to_cond_assign(ralloc_parent(ir), + vec_interpolate, + interpolant->operands[1], + ir->type); + } + + if (expr->operation != ir_binop_vector_extract) return ir; return convert_vec_index_to_cond_assign(ralloc_parent(ir), -- 2.30.2