SPV constants and constOffsets completion: isConstant() and disassembler to see results.

Expand to full isConstant() implementation.
Fix disassembler to generate texture look-up masks.

SPIRV/SpvBuilder.cpp

@@ -500,6 +500,27 @@ Id Builder::findScalarConstant(Op typeClass, Id typeId, unsigned v1, unsigned v2
     return 0;
 }
 
+bool Builder::isConstantOpCode(Op opcode) const
+{
+    switch (opcode) {
+    case OpUndef: 
+    case OpConstantTrue:
+    case OpConstantFalse:
+    case OpConstant:
+    case OpConstantComposite:
+    case OpConstantSampler:
+    case OpConstantNull:
+    case OpSpecConstantTrue:
+    case OpSpecConstantFalse:
+    case OpSpecConstant:
+    case OpSpecConstantComposite:
+    case OpSpecConstantOp:
+        return true;
+    default:
+        return false;
+    }
+}
+
 Id Builder::makeBoolConstant(bool b)
 {
     Id typeId = makeBoolType();
@@ -1194,7 +1215,6 @@ Id Builder::createTextureCall(Decoration precision, Id resultType, bool fetch, b
             mask = (ImageOperandsMask)(mask | ImageOperandsOffsetMask);
         texArgs[numArgs++] = parameters.offset;
     }
-    // TBD: if Offset is constant, use ImageOperandsConstOffsetMask
     if (parameters.offsets) {
         mask = (ImageOperandsMask)(mask | ImageOperandsConstOffsetsMask);
         texArgs[numArgs++] = parameters.offsets;

SPIRV/SpvBuilder.h

@@ -136,11 +136,8 @@ public:
     bool isSamplerType(Id typeId)   const { return getTypeClass(typeId) == OpTypeSampler; }
     bool isSampledImageType(Id typeId)   const { return getTypeClass(typeId) == OpTypeSampledImage; }
 
-    bool isConstant(Id resultId) const
-    {
-        Op opCode = getOpCode(resultId);
-        return opCode == OpConstantTrue || opCode == OpConstantFalse || opCode == OpConstant || opCode == OpConstantComposite || opCode == OpConstantNull;
-    }
+    bool isConstantOpCode(Op opcode) const;
+    bool isConstant(Id resultId) const { return isConstantOpCode(getOpCode(resultId)); }
     bool isConstantScalar(Id resultId) const { return getOpCode(resultId) == OpConstant; }
     unsigned int getConstantScalar(Id resultId) const { return module.getInstruction(resultId)->getImmediateOperand(0); }
 

SPIRV/disassemble.cpp

@@ -398,7 +398,7 @@ void SpirvStream::disassembleInstruction(Id resultId, Id /*typeId*/, Op opCode,
             disassembleIds(numOperands);
             return;
         case OperandOptionalImage:
-            outputMask(operandClass, stream[word++]);
+            outputMask(OperandImageOperands, stream[word++]);
             --numOperands;
             disassembleIds(numOperands);
             return;