SPV: Use heuristic to avoid geometry multi-streams when possible.

SPIRV/GlslangToSpv.cpp

@@ -1803,7 +1803,7 @@ spv::Id TGlslangToSpvTraverser::convertGlslangToSpvType(const glslang::TType& ty
             // Decorate the structure
             addDecoration(spvType, TranslateLayoutDecoration(type, qualifier.layoutMatrix));
             addDecoration(spvType, TranslateBlockDecoration(type));
-            if (type.getQualifier().hasStream()) {
+            if (type.getQualifier().hasStream() && glslangIntermediate->isMultiStream()) {
                 builder.addCapability(spv::CapabilityGeometryStreams);
                 builder.addDecoration(spvType, spv::DecorationStream, type.getQualifier().layoutStream);
             }
@@ -3599,7 +3599,7 @@ spv::Id TGlslangToSpvTraverser::getSymbolId(const glslang::TIntermSymbol* symbol
     }
 
     addDecoration(id, TranslateInvariantDecoration(symbol->getType().getQualifier()));
-    if (symbol->getQualifier().hasStream()) {
+    if (symbol->getQualifier().hasStream() && glslangIntermediate->isMultiStream()) {
         builder.addCapability(spv::CapabilityGeometryStreams);
         builder.addDecoration(id, spv::DecorationStream, symbol->getQualifier().layoutStream);
     }

Test/baseResults/spv.330.geom.out

@@ -9,7 +9,6 @@ Linked geometry stage:
 
                               Capability Geometry
                               Capability ClipDistance
-                              Capability GeometryStreams
                1:             ExtInstImport  "GLSL.std.450"
                               MemoryModel Logical GLSL450
                               EntryPoint Geometry 4  "main" 13 20
@@ -31,8 +30,6 @@ Linked geometry stage:
                               MemberDecorate 11(gl_PerVertex) 0 BuiltIn Position
                               MemberDecorate 11(gl_PerVertex) 1 BuiltIn ClipDistance
                               Decorate 11(gl_PerVertex) Block
-                              Decorate 11(gl_PerVertex) Stream 0
-                              Decorate 13 Stream 0
                               MemberDecorate 16(gl_PerVertex) 0 BuiltIn Position
                               MemberDecorate 16(gl_PerVertex) 1 BuiltIn ClipDistance
                               Decorate 16(gl_PerVertex) Block

glslang/MachineIndependent/ParseHelper.cpp

@@ -1524,6 +1524,11 @@ void TParseContext::builtInOpCheck(const TSourceLoc& loc, const TFunction& fnCan
         }
         break;
 
+    case EOpEmitStreamVertex:
+    case EOpEndStreamPrimitive:
+        intermediate.setMultiStream();
+        break;
+
     default:
         break;
     }
@@ -4050,6 +4055,8 @@ void TParseContext::setLayoutQualifier(const TSourceLoc& loc, TPublicType& publi
         if (id == "stream") {
             requireProfile(loc, ~EEsProfile, "selecting output stream");
             publicType.qualifier.layoutStream = value;
+            if (value > 0)
+                intermediate.setMultiStream();
             return;
         }
         break;

glslang/MachineIndependent/localintermediate.h

@@ -128,7 +128,8 @@ public:
         numMains(0), numErrors(0), numPushConstants(0), recursive(false),
         invocations(TQualifier::layoutNotSet), vertices(TQualifier::layoutNotSet), inputPrimitive(ElgNone), outputPrimitive(ElgNone),
         pixelCenterInteger(false), originUpperLeft(false),
-        vertexSpacing(EvsNone), vertexOrder(EvoNone), pointMode(false), earlyFragmentTests(false), depthLayout(EldNone), depthReplacing(false), blendEquations(0), xfbMode(false)
+        vertexSpacing(EvsNone), vertexOrder(EvoNone), pointMode(false), earlyFragmentTests(false), depthLayout(EldNone), depthReplacing(false), blendEquations(0),
+        multiStream(false), xfbMode(false)
     {
         localSize[0] = 1;
         localSize[1] = 1;
@@ -271,6 +272,8 @@ public:
 
     void setXfbMode() { xfbMode = true; }
     bool getXfbMode() const { return xfbMode; }
+    void setMultiStream() { multiStream = true; }
+    bool isMultiStream() const { return multiStream; }
     bool setOutputPrimitive(TLayoutGeometry p)
     {
         if (outputPrimitive != ElgNone)
@@ -361,6 +364,7 @@ protected:
     bool depthReplacing;
     int blendEquations;        // an 'or'ing of masks of shifts of TBlendEquationShift
     bool xfbMode;
+    bool multiStream;
 
     typedef std::list<TCall> TGraph;
     TGraph callGraph;