GLSL/SPV: XFB: No streams on types, but support them on built-in blocks.

From internal Khronos discussions, work, and testing.

SPIRV/GlslangToSpv.cpp

@@ -3279,10 +3279,6 @@ void TGlslangToSpvTraverser::decorateStructType(const glslang::TType& type,
     // Decorate the structure
     builder.addDecoration(spvType, TranslateLayoutDecoration(type, qualifier.layoutMatrix));
     builder.addDecoration(spvType, TranslateBlockDecoration(type, glslangIntermediate->usingStorageBuffer()));
-    if (type.getQualifier().hasStream() && glslangIntermediate->isMultiStream()) {
-        builder.addCapability(spv::CapabilityGeometryStreams);
-        builder.addDecoration(spvType, spv::DecorationStream, type.getQualifier().layoutStream);
-    }
 }
 
 // Turn the expression forming the array size into an id.

Test/baseResults/spv.150.geom.out

@@ -38,14 +38,12 @@ spv.150.geom
                               MemberName 68(toFragment) 0  "color"
                               Name 70  "toF"
                               Decorate 8(fromVertex) Block
-                              Decorate 8(fromVertex) Stream 3
                               Decorate 10 Stream 3
                               Decorate 13(fromVertex) Block
                               MemberDecorate 27(gl_PerVertex) 0 BuiltIn Position
                               MemberDecorate 27(gl_PerVertex) 1 BuiltIn PointSize
                               MemberDecorate 27(gl_PerVertex) 2 BuiltIn ClipDistance
                               Decorate 27(gl_PerVertex) Block
-                              Decorate 27(gl_PerVertex) Stream 0
                               Decorate 29 Stream 0
                               MemberDecorate 30(gl_PerVertex) 0 BuiltIn Position
                               MemberDecorate 30(gl_PerVertex) 1 BuiltIn PointSize
@@ -57,7 +55,6 @@ spv.150.geom
                               Decorate 51(gl_Layer) Stream 0
                               Decorate 51(gl_Layer) BuiltIn Layer
                               Decorate 68(toFragment) Block
-                              Decorate 68(toFragment) Stream 3
                               Decorate 70(toF) Stream 3
                2:             TypeVoid
                3:             TypeFunction 2

Test/baseResults/spv.420.geom.out

@@ -36,7 +36,6 @@ spv.420.geom
                               Decorate 9(gl_PerVertex) Block
                               MemberDecorate 21(gl_PerVertex) 0 BuiltIn PointSize
                               Decorate 21(gl_PerVertex) Block
-                              Decorate 21(gl_PerVertex) Stream 0
                               Decorate 23 Stream 0
                               Decorate 28(gl_ViewportIndex) Stream 0
                               Decorate 28(gl_ViewportIndex) BuiltIn ViewportIndex

glslang/MachineIndependent/ParseHelper.cpp

@@ -4059,6 +4059,8 @@ void TParseContext::redeclareBuiltinBlock(const TSourceLoc& loc, TTypeList& newT
     if (currentBlockQualifier.storage == EvqVaryingOut && globalOutputDefaults.hasXfbBuffer()) {
         if (!currentBlockQualifier.hasXfbBuffer())
             currentBlockQualifier.layoutXfbBuffer = globalOutputDefaults.layoutXfbBuffer;
+        if (!currentBlockQualifier.hasStream())
+            currentBlockQualifier.layoutStream = globalOutputDefaults.layoutStream;
         fixXfbOffsets(currentBlockQualifier, newTypeList);
     }
 
@@ -4141,6 +4143,9 @@ void TParseContext::redeclareBuiltinBlock(const TSourceLoc& loc, TTypeList& newT
             if (newType.getQualifier().hasXfbBuffer() &&
                 newType.getQualifier().layoutXfbBuffer != currentBlockQualifier.layoutXfbBuffer)
                 error(memberLoc, "member cannot contradict block (or what block inherited from global)", "xfb_buffer", "");
+            if (newType.getQualifier().hasStream() &&
+                newType.getQualifier().layoutStream != currentBlockQualifier.layoutStream)
+                error(memberLoc, "member cannot contradict block (or what block inherited from global)", "xfb_stream", "");
             oldType.getQualifier().centroid = newType.getQualifier().centroid;
             oldType.getQualifier().sample = newType.getQualifier().sample;
             oldType.getQualifier().invariant = newType.getQualifier().invariant;
@@ -4152,8 +4157,8 @@ void TParseContext::redeclareBuiltinBlock(const TSourceLoc& loc, TTypeList& newT
             oldType.getQualifier().layoutXfbBuffer = newType.getQualifier().layoutXfbBuffer;
             oldType.getQualifier().layoutXfbStride = newType.getQualifier().layoutXfbStride;
             if (oldType.getQualifier().layoutXfbOffset != TQualifier::layoutXfbBufferEnd) {
-                // if any member as an xfb_offset, then the block's xfb_buffer inherents current xfb_buffer,
+                // If any member has an xfb_offset, then the block's xfb_buffer inherents current xfb_buffer,
-                // and for xfb processing, the member needs it as well, along with xfb_stride
+                // and for xfb processing, the member needs it as well, along with xfb_stride.
                 type.getQualifier().layoutXfbBuffer = currentBlockQualifier.layoutXfbBuffer;
                 oldType.getQualifier().layoutXfbBuffer = currentBlockQualifier.layoutXfbBuffer;
             }
@@ -4178,6 +4183,11 @@ void TParseContext::redeclareBuiltinBlock(const TSourceLoc& loc, TTypeList& newT
         }
     }
 
+    if (spvVersion.vulkan > 0) {
+        // ...then streams apply to built-in blocks, instead of them being only on stream 0
+        type.getQualifier().layoutStream = currentBlockQualifier.layoutStream;
+    }
+
     if (numOriginalMembersFound < newTypeList.size())
         error(loc, "block redeclaration has extra members", blockName.c_str(), "");
     if (type.isArray() != (arraySizes != nullptr) ||