[SIL] Add source formal type to checked_cast_br.

It is necessary for opaque values where for casts that will newly start
out as checked_cast_brs and be lowered to checked_cast_addr_brs, since
the latter has the source formal type, IRGen relies on being able to
access it, and there's no way in general to obtain the source formal
type from the source lowered type.

Author: nate-chandler

SwiftCompilerSources/Sources/Optimizer/InstructionSimplification/SimplifyRefCasts.swift

@@ -36,13 +36,13 @@ private extension UnaryInstruction {
   /// ```
   ///   %2 = upcast %1 : $Derived to $Base
   ///   %3 = init_existential_ref %2 : $Base : $Base, $AnyObject
-  ///   checked_cast_br %3 : $AnyObject to Derived, bb1, bb2
+  ///   checked_cast_br AnyObject in %3 : $AnyObject to Derived, bb1, bb2
   /// ```
   ///
   /// This makes it more likely that the cast can be constant folded because the source
   /// operand's type is more accurate. In the example above, the cast reduces to
   /// ```
-  ///   checked_cast_br %1 : $Derived to Derived, bb1, bb2
+  ///   checked_cast_br Derived in %1 : $Derived to Derived, bb1, bb2
   /// ```
   /// which can be trivially folded to always-succeeds.
   ///
@@ -97,13 +97,13 @@ private extension UnaryInstruction {
 /// For example:
 /// ```
 ///   %inst = upcast %sourceValue : $Derived to $Base
-///   checked_cast_br %inst : $Base to Derived, success_block, failure_block
+///   checked_cast_br Base in %inst : $Base to Derived, success_block, failure_block
 ///   ...
 /// failure_block(%oldArg : $Base):
 /// ```
 /// is converted to:
 /// ```
-///   checked_cast_br %sourceValue : $Derived to Derived, success_block, failure_block
+///   checked_cast_br Derived in %sourceValue : $Derived to Derived, success_block, failure_block
 ///   ...
 /// failure_block(%newArg : $Derived):
 ///   %3 = upcast %newArg : $Derived to $Base

docs/SIL.rst

@@ -2082,7 +2082,7 @@ derived from the ARC object. As an example, consider the following Swift/SIL::
 
     // Consume '%1'. This means '%1' can no longer be used after this point. We
     // rebind '%1' in the destination blocks (bbYes, bbNo).
-    checked_cast_br %1 : $Klass to $OtherKlass, bbYes, bbNo
+    checked_cast_br Klass in %1 : $Klass to $OtherKlass, bbYes, bbNo
 
   bbYes(%2 : @owned $OtherKlass): // On success, the checked_cast_br forwards
                                   // '%1' into '%2' after casting to OtherKlass.
@@ -8097,9 +8097,9 @@ checked_cast_br
                       sil-identifier ',' sil-identifier
   sil-checked-cast-exact ::= '[' 'exact' ']'
 
-  checked_cast_br %0 : $A to $B, bb1, bb2
-  checked_cast_br %0 : $*A to $*B, bb1, bb2
-  checked_cast_br [exact] %0 : $A to $A, bb1, bb2
+  checked_cast_br A in %0 : $A to $B, bb1, bb2
+  checked_cast_br *A in %0 : $*A to $*B, bb1, bb2
+  checked_cast_br [exact] A in %0 : $A to $A, bb1, bb2
   // $A and $B must be both object types or both address types
   // bb1 must take a single argument of type $B or $*B
   // bb2 must take no arguments

include/swift/SIL/SILBuilder.h

@@ -2575,17 +2575,18 @@ class SILBuilder {
   }
 
   CheckedCastBranchInst *
-  createCheckedCastBranch(SILLocation Loc, bool isExact, SILValue op,
-                          SILType destLoweredTy, CanType destFormalTy,
-                          SILBasicBlock *successBB,
+  createCheckedCastBranch(SILLocation Loc, bool isExact, SILValue op, 
+                          CanType srcFormalTy, SILType destLoweredTy, 
+                          CanType destFormalTy, SILBasicBlock *successBB,
                           SILBasicBlock *failureBB,
                           ProfileCounter Target1Count = ProfileCounter(),
                           ProfileCounter Target2Count = ProfileCounter());
 
   CheckedCastBranchInst *
-  createCheckedCastBranch(SILLocation Loc, bool isExact, SILValue op,
-                          SILType destLoweredTy, CanType destFormalTy,
-                          SILBasicBlock *successBB, SILBasicBlock *failureBB,
+  createCheckedCastBranch(SILLocation Loc, bool isExact, SILValue op, 
+                          CanType srcFormalTy, SILType destLoweredTy, 
+                          CanType destFormalTy, SILBasicBlock *successBB, 
+                          SILBasicBlock *failureBB,
                           ValueOwnershipKind forwardingOwnershipKind,
                           ProfileCounter Target1Count = ProfileCounter(),
                           ProfileCounter Target2Count = ProfileCounter());

include/swift/SIL/SILCloner.h

@@ -3128,6 +3128,7 @@ SILCloner<ImplClass>::visitCheckedCastBranchInst(CheckedCastBranchInst *Inst) {
       Inst, getBuilder().createCheckedCastBranch(
                 getOpLocation(Inst->getLoc()), Inst->isExact(),
                 getOpValue(Inst->getOperand()),
+                getOpASTType(Inst->getSourceFormalType()),
                 getOpType(Inst->getTargetLoweredType()),
                 getOpASTType(Inst->getTargetFormalType()), OpSuccBB, OpFailBB,
                 Inst->getForwardingOwnershipKind(), TrueCount, FalseCount));

include/swift/SIL/SILInstruction.h

@@ -10024,12 +10024,13 @@ class CheckedCastBranchInst final
           CastBranchInstBase<OwnershipForwardingTermInst>> {
   friend SILBuilder;
 
+  CanType SrcFormalTy;
   SILType DestLoweredTy;
   CanType DestFormalTy;
   bool IsExact;
 
   CheckedCastBranchInst(SILDebugLocation DebugLoc, bool IsExact,
-                        SILValue Operand,
+                        SILValue Operand, CanType SrcFormalTy,
                         ArrayRef<SILValue> TypeDependentOperands,
                         SILType DestLoweredTy, CanType DestFormalTy,
                         SILBasicBlock *SuccessBB, SILBasicBlock *FailureBB,
@@ -10041,21 +10042,21 @@ class CheckedCastBranchInst final
             DebugLoc, Operand, TypeDependentOperands, SuccessBB, FailureBB,
             Target1Count, Target2Count, forwardingOwnershipKind,
             preservesOwnership),
-        DestLoweredTy(DestLoweredTy), DestFormalTy(DestFormalTy),
-        IsExact(IsExact) {}
+        SrcFormalTy(SrcFormalTy), DestLoweredTy(DestLoweredTy),
+        DestFormalTy(DestFormalTy), IsExact(IsExact) {}
 
   static CheckedCastBranchInst *
   create(SILDebugLocation DebugLoc, bool IsExact, SILValue Operand,
-         SILType DestLoweredTy, CanType DestFormalTy, SILBasicBlock *SuccessBB,
-         SILBasicBlock *FailureBB, SILFunction &F,
+         CanType SrcFormalTy, SILType DestLoweredTy, CanType DestFormalTy,
+         SILBasicBlock *SuccessBB, SILBasicBlock *FailureBB, SILFunction &F,
          ProfileCounter Target1Count, ProfileCounter Target2Count,
          ValueOwnershipKind forwardingOwnershipKind);
 
 public:
   bool isExact() const { return IsExact; }
 
   SILType getSourceLoweredType() const { return getOperand()->getType(); }
-  CanType getSourceFormalType() const { return getSourceLoweredType().getASTType(); }
+  CanType getSourceFormalType() const { return SrcFormalTy; }
 
   SILType getTargetLoweredType() const { return DestLoweredTy; }
   CanType getTargetFormalType() const { return DestFormalTy; }

lib/IRGen/GenCast.cpp

@@ -125,7 +125,7 @@ FailableCastResult irgen::emitClassIdenticalCast(IRGenFunction &IGF,
   // of the metatype value to the subclass's static metatype instance.
   //
   // %1 = value_metatype $Super.Type, %0 : $A
-  // checked_cast_br [exact] %1 : $Super.Type to $Sub.Type
+  // checked_cast_br [exact] Super.Type in %1 : $Super.Type to $Sub.Type
   // =>
   // icmp eq %1, @metadata.Sub
   llvm::Value *objectMetadata = isMetatype ? from :

lib/SIL/IR/SILBuilder.cpp

@@ -675,7 +675,7 @@ void SILBuilder::emitScopedBorrowOperation(SILLocation loc, SILValue original,
 /// Example:
 ///
 ///     %mt = metatype $@thick C.Type
-///     checked_cast_br %mt : $@thick C.Type to AnyObject.Type, bb1, bb2,
+///     checked_cast_br C.Type in %mt : $@thick C.Type to AnyObject.Type, bb1, bb2,
 ///                           forwarding: @owned
 ///   bb1(%arg : @owned AnyObject.Type):
 ///
@@ -717,30 +717,30 @@ SwitchEnumInst *SILBuilder::createSwitchEnum(
 }
 
 CheckedCastBranchInst *SILBuilder::createCheckedCastBranch(
-    SILLocation Loc, bool isExact, SILValue op,
-    SILType destLoweredTy, CanType destFormalTy,
-    SILBasicBlock *successBB, SILBasicBlock *failureBB,
-    ProfileCounter target1Count, ProfileCounter target2Count) {
+    SILLocation Loc, bool isExact, SILValue op, CanType srcFormalTy,
+    SILType destLoweredTy, CanType destFormalTy, SILBasicBlock *successBB,
+    SILBasicBlock *failureBB, ProfileCounter target1Count,
+    ProfileCounter target2Count) {
   auto forwardingOwnership =
       deriveForwardingOwnership(op, destLoweredTy, getFunction());
-  return createCheckedCastBranch(Loc, isExact, op, destLoweredTy, destFormalTy,
-                                 successBB, failureBB, forwardingOwnership,
-                                 target1Count, target2Count);
+  return createCheckedCastBranch(
+      Loc, isExact, op, srcFormalTy, destLoweredTy, destFormalTy, successBB,
+      failureBB, forwardingOwnership, target1Count, target2Count);
 }
 
 CheckedCastBranchInst *SILBuilder::createCheckedCastBranch(
-    SILLocation Loc, bool isExact, SILValue op, SILType destLoweredTy,
-    CanType destFormalTy, SILBasicBlock *successBB, SILBasicBlock *failureBB,
-    ValueOwnershipKind forwardingOwnershipKind, ProfileCounter target1Count,
-    ProfileCounter target2Count) {
+    SILLocation Loc, bool isExact, SILValue op, CanType srcFormalTy,
+    SILType destLoweredTy, CanType destFormalTy, SILBasicBlock *successBB,
+    SILBasicBlock *failureBB, ValueOwnershipKind forwardingOwnershipKind,
+    ProfileCounter target1Count, ProfileCounter target2Count) {
   assert((!hasOwnership() || !failureBB->getNumArguments() ||
           failureBB->getArgument(0)->getType() == op->getType()) &&
          "failureBB's argument doesn't match incoming argument type");
 
   return insertTerminator(CheckedCastBranchInst::create(
-      getSILDebugLocation(Loc), isExact, op, destLoweredTy, destFormalTy,
-      successBB, failureBB, getFunction(), target1Count, target2Count,
-      forwardingOwnershipKind));
+      getSILDebugLocation(Loc), isExact, op, srcFormalTy, destLoweredTy,
+      destFormalTy, successBB, failureBB, getFunction(), target1Count,
+      target2Count, forwardingOwnershipKind));
 }
 
 void SILBuilderWithScope::insertAfter(SILInstruction *inst,

lib/SIL/IR/SILInstructions.cpp

@@ -2551,8 +2551,8 @@ UnconditionalCheckedCastInst *UnconditionalCheckedCastInst::create(
 
 CheckedCastBranchInst *CheckedCastBranchInst::create(
     SILDebugLocation DebugLoc, bool IsExact, SILValue Operand,
-    SILType DestLoweredTy, CanType DestFormalTy, SILBasicBlock *SuccessBB,
-    SILBasicBlock *FailureBB, SILFunction &F,
+    CanType SrcFormalTy, SILType DestLoweredTy, CanType DestFormalTy,
+    SILBasicBlock *SuccessBB, SILBasicBlock *FailureBB, SILFunction &F,
     ProfileCounter Target1Count, ProfileCounter Target2Count,
     ValueOwnershipKind forwardingOwnershipKind) {
   SILModule &module = F.getModule();
@@ -2561,12 +2561,12 @@ CheckedCastBranchInst *CheckedCastBranchInst::create(
   SmallVector<SILValue, 8> TypeDependentOperands;
   collectTypeDependentOperands(TypeDependentOperands, F, DestFormalTy);
   unsigned size =
-      totalSizeToAlloc<swift::Operand>(1 + TypeDependentOperands.size());
+      totalSizeToAlloc<swift::Operand>(3 + TypeDependentOperands.size());
   void *Buffer = module.allocateInst(size, alignof(CheckedCastBranchInst));
   return ::new (Buffer) CheckedCastBranchInst(
-      DebugLoc, IsExact, Operand, TypeDependentOperands, DestLoweredTy,
-      DestFormalTy, SuccessBB, FailureBB, Target1Count, Target2Count,
-      forwardingOwnershipKind, preservesOwnership);
+      DebugLoc, IsExact, Operand, SrcFormalTy, TypeDependentOperands,
+      DestLoweredTy, DestFormalTy, SuccessBB, FailureBB, Target1Count,
+      Target2Count, forwardingOwnershipKind, preservesOwnership);
 }
 
 MetatypeInst *MetatypeInst::create(SILDebugLocation Loc, SILType Ty,

lib/SIL/IR/SILPrinter.cpp

@@ -1914,6 +1914,7 @@ class SILPrinter : public SILInstructionVisitor<SILPrinter> {
   void visitCheckedCastBranchInst(CheckedCastBranchInst *CI) {
     if (CI->isExact())
       *this << "[exact] ";
+    *this << CI->getSourceFormalType() << " in ";
     *this << getIDAndType(CI->getOperand()) << " to " << CI->getTargetFormalType()
           << ", " << Ctx.getID(CI->getSuccessBB()) << ", "
           << Ctx.getID(CI->getFailureBB());

lib/SIL/Parser/ParseSIL.cpp

@@ -4489,6 +4489,9 @@ bool SILParser::parseSpecificSILInstruction(SILBuilder &B,
         parseSILOptional(isExact, *this, "exact"))
       return true;
 
+    if (parseASTType(SourceType) || parseVerbatim("in"))
+      return true;
+
     if (parseTypedValueRef(Val, B) || parseVerbatim("to") ||
         parseASTType(TargetType) || parseConditionalBranchDestinations())
       return true;
@@ -4501,8 +4504,9 @@ bool SILParser::parseSpecificSILInstruction(SILBuilder &B,
 
     auto opaque = Lowering::AbstractionPattern::getOpaque();
     ResultVal = B.createCheckedCastBranch(
-        InstLoc, isExact, Val, F->getLoweredType(opaque, TargetType),
-        TargetType, getBBForReference(SuccessBBName, SuccessBBLoc),
+        InstLoc, isExact, Val, SourceType,
+        F->getLoweredType(opaque, TargetType), TargetType,
+        getBBForReference(SuccessBBName, SuccessBBLoc),
         getBBForReference(FailureBBName, FailureBBLoc), forwardingOwnership);
     break;
   }