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authorNicolai Hähnle <[email protected]>2016-10-13 09:54:02 +0200
committerNicolai Hähnle <[email protected]>2016-10-17 19:09:39 +0200
commit9d6f82320c8a7f0df10f0b7868d966be907e6b21 (patch)
treebf7ee5412bcc936c17530831573e8aa8f6c473aa
parent57a15142037e3eea3581a6c690b8e8e93729b5b3 (diff)
st/glsl_to_tgsi: fix a corner case of std140 layout in uniform buffers
See the comment in the code for an explanation. This fixes GL45-CTS.buffer_storage.map_persistent_draw. Reviewed-by: Marek Olšák <[email protected]>
-rw-r--r--src/mesa/state_tracker/st_glsl_to_tgsi.cpp29
1 files changed, 28 insertions, 1 deletions
diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index fd2485de892..a7ea19fb239 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -2110,8 +2110,35 @@ glsl_to_tgsi_visitor::visit_expression(ir_expression* ir, st_src_reg *op)
cbuf.index = const_offset / 16;
}
else {
+ ir_expression *offset_expr = ir->operands[1]->as_expression();
+ st_src_reg offset = op[1];
+
+ /* The OpenGL spec is written in such a way that accesses with
+ * non-constant offset are almost always vec4-aligned. The only
+ * exception to this are members of structs in arrays of structs:
+ * each struct in an array of structs is at least vec4-aligned,
+ * but single-element and [ui]vec2 members of the struct may be at
+ * an offset that is not a multiple of 16 bytes.
+ *
+ * Here, we extract that offset, relying on previous passes to always
+ * generate offset expressions of the form (+ expr constant_offset).
+ *
+ * Note that the std430 layout, which allows more cases of alignment
+ * less than vec4 in arrays, is not supported for uniform blocks, so
+ * we do not have to deal with it here.
+ */
+ if (offset_expr && offset_expr->operation == ir_binop_add) {
+ const_offset_ir = offset_expr->operands[1]->as_constant();
+ if (const_offset_ir) {
+ const_offset = const_offset_ir->value.u[0];
+ cbuf.index = const_offset / 16;
+ offset_expr->operands[0]->accept(this);
+ offset = this->result;
+ }
+ }
+
/* Relative/variable index into constant buffer */
- emit_asm(ir, TGSI_OPCODE_USHR, st_dst_reg(index_reg), op[1],
+ emit_asm(ir, TGSI_OPCODE_USHR, st_dst_reg(index_reg), offset,
st_src_reg_for_int(4));
cbuf.reladdr = ralloc(mem_ctx, st_src_reg);
memcpy(cbuf.reladdr, &index_reg, sizeof(index_reg));