Mesa (master): spirv: Don't emit RMW for vector indexing in shared or global
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Tue Aug 18 20:39:44 UTC 2020
Module: Mesa
Branch: master
Commit: b479de8537ad34ec56d61f87d53a327a175eab36
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=b479de8537ad34ec56d61f87d53a327a175eab36
Author: Jason Ekstrand <jason at jlekstrand.net>
Date: Mon Aug 17 10:51:32 2020 -0500
spirv: Don't emit RMW for vector indexing in shared or global
Anything that fails the is_external_block check is getting the
vtn_local_load/store path which does read-modify-write which isn't
correct if the variable mode can be written cross-workgroup.
Cc: mesa-stable at lists.freedesktop.org
Reviewed-by: Jesse Natalie <jenatali at microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6372>
---
src/compiler/spirv/vtn_variables.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)
diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index 47932f0cd16..1cb848a3af8 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -124,6 +124,18 @@ vtn_mode_uses_ssa_offset(struct vtn_builder *b,
mode == vtn_variable_mode_push_constant;
}
+static bool
+vtn_mode_is_cross_invocation(struct vtn_builder *b,
+ enum vtn_variable_mode mode)
+{
+ return mode == vtn_variable_mode_ssbo ||
+ mode == vtn_variable_mode_ubo ||
+ mode == vtn_variable_mode_phys_ssbo ||
+ mode == vtn_variable_mode_push_constant ||
+ mode == vtn_variable_mode_workgroup ||
+ mode == vtn_variable_mode_cross_workgroup;
+}
+
static bool
vtn_pointer_is_external_block(struct vtn_builder *b,
struct vtn_pointer *ptr)
@@ -1074,11 +1086,11 @@ _vtn_variable_load_store(struct vtn_builder *b, bool load,
if (glsl_type_is_vector_or_scalar(ptr->type->type)) {
/* We hit a vector or scalar; go ahead and emit the load[s] */
nir_deref_instr *deref = vtn_pointer_to_deref(b, ptr);
- if (vtn_pointer_is_external_block(b, ptr)) {
- /* If it's external, we call nir_load/store_deref directly. The
- * vtn_local_load/store helpers are too clever and do magic to
- * avoid array derefs of vectors. That magic is both less
- * efficient than the direct load/store and, in the case of
+ if (vtn_mode_is_cross_invocation(b, ptr->mode)) {
+ /* If it's cross-invocation, we call nir_load/store_deref
+ * directly. The vtn_local_load/store helpers are too clever and
+ * do magic to avoid array derefs of vectors. That magic is both
+ * less efficient than the direct load/store and, in the case of
* stores, is broken because it creates a race condition if two
* threads are writing to different components of the same vector
* due to the load+insert+store it uses to emulate the array
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