[PATCH v3 3/4] vkd3d-shader/ir: Trim non-arrayable sysvals from the last element of an index range.

[Conor McCarthy]

From: Conor McCarthy

FXC may erroneously emit a dcl_indexrange beyond the bounds of the
addressed range. If this includes a sysval, it will be erroneously
included in the arrayed signature element. We could trim more than one
from the end, but it is very rare to have even one. A sysval at index 0
is a more complex case, which is not handled.
---
 libs/vkd3d-shader/ir.c | 13 ++++++++++++-
 tests/d3d12.c          |  1 -
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/libs/vkd3d-shader/ir.c b/libs/vkd3d-shader/ir.c
index 7a3c9d681..b63fcab53 100644
--- a/libs/vkd3d-shader/ir.c
+++ b/libs/vkd3d-shader/ir.c
@@ -650,10 +650,15 @@ static void io_normaliser_add_index_range(struct io_normaliser *normaliser,
 {
     const struct vkd3d_shader_index_range *range = &ins->declaration.index_range;
     const struct vkd3d_shader_register *reg = &range->dst.reg;
+    unsigned int register_count = range->register_count;
+    enum vkd3d_shader_sysval_semantic sysval_semantic;
     unsigned int reg_idx, write_mask, element_idx;
     const struct shader_signature *signature;
     uint8_t (*range_map)[VKD3D_VEC4_SIZE];

+    if (!register_count)
+        return;
+
     switch (reg->type)
     {
         case VKD3DSPR_INPUT:
@@ -685,7 +690,13 @@ static void io_normaliser_add_index_range(struct io_normaliser *normaliser,
     reg_idx = reg->idx[reg->idx_count - 1].offset;
     write_mask = range->dst.write_mask;
     element_idx = shader_signature_find_element_for_reg(signature, reg_idx, write_mask);
-    range_map_set_register_range(range_map, reg_idx, range->register_count,
+    sysval_semantic = signature->elements[element_idx + register_count - 1].sysval_semantic;
+    /* Trim the last element if it's a non-arrayable sysval. FXC seems to forbid actual addressing
+     * of such a sysval, but it can erroneously include it in a dcl_indexrange. */
+    register_count -= sysval_semantic && !vsir_sysval_semantic_is_tess_factor(sysval_semantic)
+            && !vsir_sysval_semantic_is_clip_cull(sysval_semantic);
+
+    range_map_set_register_range(range_map, reg_idx, register_count,
             signature->elements[element_idx].mask, true);
 }

diff --git a/tests/d3d12.c b/tests/d3d12.c
index b84c58543..ec6e065c0 100644
--- a/tests/d3d12.c
+++ b/tests/d3d12.c
@@ -37739,7 +37739,6 @@ static void test_hull_shader_punned_array(void)
     transition_resource_state(command_list, context.render_target,
             D3D12_RESOURCE_STATE_RENDER_TARGET, D3D12_RESOURCE_STATE_COPY_SOURCE);

-    todo
     check_sub_resource_uint(context.render_target, 0, queue, command_list, 0xff00ff00, 0);

destroy_test_context(&context);