HLSL: Translate directive [flatten] and [branch] to SPV control mask.

SPIRV/GlslangToSpv.cpp

@@ -122,6 +122,7 @@ protected:
     spv::Decoration TranslateAuxiliaryStorageDecoration(const glslang::TQualifier& qualifier);
     spv::BuiltIn TranslateBuiltInDecoration(glslang::TBuiltInVariable, bool memberDeclaration);
     spv::ImageFormat TranslateImageFormat(const glslang::TType& type);
+    spv::SelectionControlMask TranslateSelectionControl(glslang::TSelectionControl) const;
     spv::LoopControlMask TranslateLoopControl(glslang::TLoopControl) const;
     spv::StorageClass TranslateStorageClass(const glslang::TType&);
     spv::Id createSpvVariable(const glslang::TIntermSymbol*);
@@ -741,6 +742,16 @@ spv::ImageFormat TGlslangToSpvTraverser::TranslateImageFormat(const glslang::TTy
     }
 }
 
+spv::SelectionControlMask TGlslangToSpvTraverser::TranslateSelectionControl(glslang::TSelectionControl selectionControl) const
+{
+    switch (selectionControl) {
+    case glslang::ESelectionControlNone:        return spv::SelectionControlMaskNone;
+    case glslang::ESelectionControlFlatten:     return spv::SelectionControlFlattenMask;
+    case glslang::ESelectionControlDontFlatten: return spv::SelectionControlDontFlattenMask;
+    default:                                    return spv::SelectionControlMaskNone;
+    }
+}
+
 spv::LoopControlMask TGlslangToSpvTraverser::TranslateLoopControl(glslang::TLoopControl loopControl) const
 {
     switch (loopControl) {
@@ -1941,8 +1952,7 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
         return false;
     }
 
-    // Instead, emit control flow...
-
+    // Instead, emit control flow...    
     // Don't handle results as temporaries, because there will be two names
     // and better to leave SSA to later passes.
     spv::Id result = (node->getBasicType() == glslang::EbtVoid)
@@ -1952,8 +1962,11 @@ bool TGlslangToSpvTraverser::visitSelection(glslang::TVisit /* visit */, glslang
     // emit the condition before doing anything with selection
     node->getCondition()->traverse(this);
 
+    // Selection control:
+    const spv::SelectionControlMask control = TranslateSelectionControl(node->getSelectionControl());
+
     // make an "if" based on the value created by the condition
-    spv::Builder::If ifBuilder(accessChainLoad(node->getCondition()->getType()), builder);
+    spv::Builder::If ifBuilder(accessChainLoad(node->getCondition()->getType()), control, builder);
 
     // emit the "then" statement
     if (node->getTrueBlock() != nullptr) {
@@ -1991,6 +2004,9 @@ bool TGlslangToSpvTraverser::visitSwitch(glslang::TVisit /* visit */, glslang::T
     node->getCondition()->traverse(this);
     spv::Id selector = accessChainLoad(node->getCondition()->getAsTyped()->getType());
 
+    // Selection control:
+    const spv::SelectionControlMask control = TranslateSelectionControl(node->getSelectionControl());
+
     // browse the children to sort out code segments
     int defaultSegment = -1;
     std::vector<TIntermNode*> codeSegments;
@@ -2016,7 +2032,7 @@ bool TGlslangToSpvTraverser::visitSwitch(glslang::TVisit /* visit */, glslang::T
 
     // make the switch statement
     std::vector<spv::Block*> segmentBlocks; // returned, as the blocks allocated in the call
-    builder.makeSwitch(selector, (int)codeSegments.size(), caseValues, valueIndexToSegment, defaultSegment, segmentBlocks);
+    builder.makeSwitch(selector, control, (int)codeSegments.size(), caseValues, valueIndexToSegment, defaultSegment, segmentBlocks);
 
     // emit all the code in the segments
     breakForLoop.push(false);
@@ -5707,7 +5723,7 @@ spv::Id TGlslangToSpvTraverser::createShortCircuit(glslang::TOperator op, glslan
         leftId = builder.createUnaryOp(spv::OpLogicalNot, boolTypeId, leftId);
 
     // make an "if" based on the left value
-    spv::Builder::If ifBuilder(leftId, builder);
+    spv::Builder::If ifBuilder(leftId, spv::SelectionControlMaskNone, builder);
 
     // emit right operand as the "then" part of the "if"
     builder.clearAccessChain();

SPIRV/SpvBuilder.cpp

@@ -2009,9 +2009,10 @@ Id Builder::createMatrixConstructor(Decoration precision, const std::vector<Id>&
 }
 
 // Comments in header
-Builder::If::If(Id cond, Builder& gb) :
+Builder::If::If(Id cond, unsigned int ctrl, Builder& gb) :
     builder(gb),
     condition(cond),
+    control(ctrl),
     elseBlock(0)
 {
     function = &builder.getBuildPoint()->getParent();
@@ -2052,7 +2053,7 @@ void Builder::If::makeEndIf()
 
     // Go back to the headerBlock and make the flow control split
     builder.setBuildPoint(headerBlock);
-    builder.createSelectionMerge(mergeBlock, SelectionControlMaskNone);
+    builder.createSelectionMerge(mergeBlock, control);
     if (elseBlock)
         builder.createConditionalBranch(condition, thenBlock, elseBlock);
     else
@@ -2064,7 +2065,7 @@ void Builder::If::makeEndIf()
 }
 
 // Comments in header
-void Builder::makeSwitch(Id selector, int numSegments, const std::vector<int>& caseValues,
+void Builder::makeSwitch(Id selector, unsigned int control, int numSegments, const std::vector<int>& caseValues,
                          const std::vector<int>& valueIndexToSegment, int defaultSegment,
                          std::vector<Block*>& segmentBlocks)
 {
@@ -2077,7 +2078,7 @@ void Builder::makeSwitch(Id selector, int numSegments, const std::vector<int>& c
     Block* mergeBlock = new Block(getUniqueId(), function);
 
     // make and insert the switch's selection-merge instruction
-    createSelectionMerge(mergeBlock, SelectionControlMaskNone);
+    createSelectionMerge(mergeBlock, control);
 
     // make the switch instruction
     Instruction* switchInst = new Instruction(NoResult, NoType, OpSwitch);

SPIRV/SpvBuilder.h

@@ -385,7 +385,7 @@ public:
     // Helper to use for building nested control flow with if-then-else.
     class If {
     public:
-        If(Id condition, Builder& builder);
+        If(Id condition, unsigned int ctrl, Builder& builder);
         ~If() {}
 
         void makeBeginElse();
@@ -397,6 +397,7 @@ public:
 
         Builder& builder;
         Id condition;
+        unsigned int control;
         Function* function;
         Block* headerBlock;
         Block* thenBlock;
@@ -416,7 +417,7 @@ public:
     // Returns the right set of basic blocks to start each code segment with, so that the caller's
     // recursion stack can hold the memory for it.
     //
-    void makeSwitch(Id condition, int numSegments, const std::vector<int>& caseValues,
+    void makeSwitch(Id condition, unsigned int control, int numSegments, const std::vector<int>& caseValues,
                     const std::vector<int>& valueToSegment, int defaultSegment, std::vector<Block*>& segmentBB); // return argument
 
     // Add a branch to the innermost switch's merge block.

SPIRV/doc.cpp

@@ -637,13 +637,15 @@ const char* SelectControlString(int cont)
     }
 }
 
-const int LoopControlCeiling = 2;
+const int LoopControlCeiling = 4;
 
 const char* LoopControlString(int cont)
 {
     switch (cont) {
     case 0:  return "Unroll";
     case 1:  return "DontUnroll";
+    case 2:  return "DependencyInfinite";
+    case 3:  return "DependencyLength";
 
     case LoopControlCeiling:
     default: return "Bad";