[sil] Add support for multiple value instructions by adding MultipleValueInstruction{,Result}.

docs/SIL.rst

@@ -784,8 +784,11 @@ Basic Blocks
   sil-label ::= sil-identifier ('(' sil-argument (',' sil-argument)* ')')? ':'
   sil-argument ::= sil-value-name ':' sil-type
 
-  sil-instruction-def ::= (sil-value-name '=')? sil-instruction
-                          (',' sil-loc)? (',' sil-scope-ref)?
+  sil-instruction-result ::= sil-value-name
+  sil-instruction-result ::= '(' (sil-value-name (',' sil-value-name)*)? ')'
+  sil-instruction-source-info ::= (',' sil-scope-ref)? (',' sil-loc)?
+  sil-instruction-def ::=
+    (sil-instruction-result '=')? sil-instruction sil-instruction-source-info
 
 A function body consists of one or more basic blocks that correspond
 to the nodes of the function's control flow graph. Each basic block
@@ -3506,6 +3509,19 @@ tuple_element_addr
 Given the address of a tuple in memory, derives the
 address of an element within that value.
 
+destructure_tuple
+`````````````````
+
+::
+
+   sil-instruction ::= 'destructure_tuple' sil-operand
+
+   (%elt1, ..., %eltn) = destructure_tuple %0 : $(Elt1Ty, ..., EltNTy)
+   // %0 must be a tuple of type $(Elt1Ty, ..., EltNTy)
+   // %eltN must have the type $EltNTy
+
+Given a tuple value, split the value into its constituent elements.
+
 struct
 ``````
 ::
@@ -3547,6 +3563,19 @@ struct_element_addr
 Given the address of a struct value in memory, derives the address of a
 physical field within the value.
 
+destructure_struct
+``````````````````
+
+::
+
+   sil-instruction ::= 'destructure_struct' sil-operand
+
+   (%elt1, ..., %eltn) = destructure_struct %0 : $S
+   // %0 must be a struct of type $S
+   // %eltN must have the same type as the Nth field of $S
+
+Given a struct, split the struct into its constituant fields.
+
 object
 ``````
 ::

include/swift/SIL/SILArgument.h

@@ -124,7 +124,8 @@ class SILArgument : public ValueBase {
   explicit SILArgument(ValueKind SubClassKind, SILType Ty,
                        ValueOwnershipKind OwnershipKind,
                        const ValueDecl *D = nullptr)
-      : ValueBase(SubClassKind, Ty), ParentBB(nullptr), Decl(D), OwnershipKind(OwnershipKind) {}
+      : ValueBase(SubClassKind, Ty, IsRepresentative::Yes), ParentBB(nullptr),
+        Decl(D), OwnershipKind(OwnershipKind) {}
   void setParent(SILBasicBlock *P) { ParentBB = P; }
 
   friend SILBasicBlock;

include/swift/SIL/SILBuilder.h

@@ -1178,6 +1178,18 @@ class SILBuilder {
                                                       Ref, ResultTy));
   }
 
+  DestructureStructInst *createDestructureStruct(SILLocation Loc,
+                                                 SILValue Operand) {
+    return insert(DestructureStructInst::create(
+        getModule(), getSILDebugLocation(Loc), Operand));
+  }
+
+  DestructureTupleInst *createDestructureTuple(SILLocation Loc,
+                                               SILValue Operand) {
+    return insert(DestructureTupleInst::create(
+        getModule(), getSILDebugLocation(Loc), Operand));
+  }
+
   ClassMethodInst *createClassMethod(SILLocation Loc, SILValue Operand,
                                      SILDeclRef Member, SILType MethodTy) {
     return insert(new (getModule()) ClassMethodInst(

include/swift/SIL/SILCloner.h

@@ -1518,9 +1518,28 @@ SILCloner<ImplClass>::visitRefTailAddrInst(RefTailAddrInst *Inst) {
                                    getOpType(Inst->getType())));
 }
 
-template<typename ImplClass>
-void
-SILCloner<ImplClass>::visitClassMethodInst(ClassMethodInst *Inst) {
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitDestructureStructInst(
+    DestructureStructInst *Inst) {
+  getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
+  doPostProcess(
+      Inst,
+      getBuilder().createDestructureStruct(getOpLocation(Inst->getLoc()),
+                                           getOpValue(Inst->getOperand())));
+}
+
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitDestructureTupleInst(
+    DestructureTupleInst *Inst) {
+  getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
+  doPostProcess(
+      Inst,
+      getBuilder().createDestructureTuple(getOpLocation(Inst->getLoc()),
+                                          getOpValue(Inst->getOperand())));
+}
+
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitClassMethodInst(ClassMethodInst *Inst) {
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   doPostProcess(Inst,
     getBuilder().createClassMethod(getOpLocation(Inst->getLoc()),