spirv: Don't fail if multiple ordering semantics bits are set

Vulkan requires that only one bit for the ordering is set, but old
versions of GLSLang just set all the bits.  This was fixed as part of
https://github.com/KhronosGroup/glslang/commit/c51287d744fb6e7e9ccc09f6f8451e6c64b1dad6
but we can still find older versions (or shaders compiled with it)
around.

So instead of failing, emit a warning and fallback to the effective
result of any combination of multiple bits: AcquireRelease.

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2018
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index e436f28de6012dd940f19785964328318d8b423d..4c1da666261c3e07c3d6faf7b31c64bfc9faa594 100644 (file)
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -1954,12 +1954,22 @@ vtn_split_barrier_semantics(struct vtn_builder *b,
    *before = SpvMemorySemanticsMaskNone;
    *after = SpvMemorySemanticsMaskNone;
 
-   const SpvMemorySemanticsMask order_semantics =
+   SpvMemorySemanticsMask order_semantics =
       semantics & (SpvMemorySemanticsAcquireMask |
                    SpvMemorySemanticsReleaseMask |
                    SpvMemorySemanticsAcquireReleaseMask |
                    SpvMemorySemanticsSequentiallyConsistentMask);
 
+   if (util_bitcount(order_semantics) > 1) {
+      /* Old GLSLang versions incorrectly set all the ordering bits.  This was
+       * fixed in c51287d744fb6e7e9ccc09f6f8451e6c64b1dad6 of glslang repo,
+       * and it is in GLSLang since revision "SPIRV99.1321" (from Jul-2016).
+       */
+      vtn_warn("Multiple memory ordering semantics specified, "
+               "assuming AcquireRelease.");
+      order_semantics = SpvMemorySemanticsAcquireReleaseMask;
+   }
+
    const SpvMemorySemanticsMask av_vis_semantics =
       semantics & (SpvMemorySemanticsMakeAvailableMask |
                    SpvMemorySemanticsMakeVisibleMask);
@@ -1979,9 +1989,6 @@ vtn_split_barrier_semantics(struct vtn_builder *b,
    if (other_semantics)
       vtn_warn("Ignoring unhandled memory semantics: %u\n", other_semantics);
 
-   vtn_fail_if(util_bitcount(order_semantics) > 1,
-               "Multiple memory ordering bits specified");
-
    /* SequentiallyConsistent is treated as AcquireRelease. */
 
    /* The RELEASE barrier happens BEFORE the operation, and it is usually
@@ -2016,10 +2023,24 @@ vtn_emit_scoped_memory_barrier(struct vtn_builder *b, SpvScope scope,
                                SpvMemorySemanticsMask semantics)
 {
    nir_memory_semantics nir_semantics = 0;
-   switch (semantics & (SpvMemorySemanticsAcquireMask |
-                        SpvMemorySemanticsReleaseMask |
-                        SpvMemorySemanticsAcquireReleaseMask |
-                        SpvMemorySemanticsSequentiallyConsistentMask)) {
+
+   SpvMemorySemanticsMask order_semantics =
+      semantics & (SpvMemorySemanticsAcquireMask |
+                   SpvMemorySemanticsReleaseMask |
+                   SpvMemorySemanticsAcquireReleaseMask |
+                   SpvMemorySemanticsSequentiallyConsistentMask);
+
+   if (util_bitcount(order_semantics) > 1) {
+      /* Old GLSLang versions incorrectly set all the ordering bits.  This was
+       * fixed in c51287d744fb6e7e9ccc09f6f8451e6c64b1dad6 of glslang repo,
+       * and it is in GLSLang since revision "SPIRV99.1321" (from Jul-2016).
+       */
+      vtn_warn("Multiple memory ordering semantics bits specified, "
+               "assuming AcquireRelease.");
+      order_semantics = SpvMemorySemanticsAcquireReleaseMask;
+   }
+
+   switch (order_semantics) {
    case 0:
       /* Not an ordering barrier. */
       break;
@@ -2039,7 +2060,7 @@ vtn_emit_scoped_memory_barrier(struct vtn_builder *b, SpvScope scope,
       break;
 
    default:
-      vtn_fail("Multiple memory ordering bits specified");
+      unreachable("Invalid memory order semantics");
    }
 
    if (semantics & SpvMemorySemanticsMakeAvailableMask) {