[NFC] Add some pretty stack traces

These would have helped us to debug rdar://142693093 more quickly.

Author: beccadax

include/swift/SIL/PrettyStackTrace.h

@@ -20,6 +20,7 @@
 
 #include "swift/SIL/SILLocation.h"
 #include "swift/SIL/SILNode.h"
+#include "swift/SIL/SILDeclRef.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/PrettyStackTrace.h"
@@ -82,6 +83,18 @@ class PrettyStackTraceSILNode : public llvm::PrettyStackTraceEntry {
   virtual void print(llvm::raw_ostream &OS) const override;
 };
 
+/// Observe that we are processing a reference to a SIL decl.
+class PrettyStackTraceSILDeclRef : public llvm::PrettyStackTraceEntry {
+  SILDeclRef declRef;
+  StringRef action;
+
+public:
+  PrettyStackTraceSILDeclRef(const char *action, SILDeclRef declRef)
+      : declRef(declRef), action(action) {}
+
+  virtual void print(llvm::raw_ostream &os) const override;
+};
+
 } // end namespace swift
 
 #endif

lib/IRGen/GenCall.cpp

@@ -20,6 +20,7 @@
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/ClangModuleLoader.h"
 #include "swift/AST/GenericEnvironment.h"
+#include "swift/AST/PrettyStackTrace.h"
 #include "swift/Basic/Assertions.h"
 #include "swift/IRGen/Linking.h"
 #include "swift/Runtime/Config.h"
@@ -1473,6 +1474,8 @@ static bool doesClangExpansionMatchSchema(IRGenModule &IGM,
 /// Expand the result and parameter types to the appropriate LLVM IR
 /// types for C, C++ and Objective-C signatures.
 void SignatureExpansion::expandExternalSignatureTypes() {
+  PrettyStackTraceType entry(IGM.Context, "using clang to expand signature for",
+                             FnType);
   assert(FnType->getLanguage() == SILFunctionLanguage::C);
 
   auto SILResultTy = [&]() {

lib/IRGen/GenDecl.cpp

@@ -34,6 +34,7 @@
 #include "swift/IRGen/Linking.h"
 #include "swift/Runtime/HeapObject.h"
 #include "swift/SIL/FormalLinkage.h"
+#include "swift/SIL/PrettyStackTrace.h"
 #include "swift/SIL/SILDebugScope.h"
 #include "swift/SIL/SILModule.h"
 #include "swift/Subsystems.h"
@@ -3515,6 +3516,7 @@ llvm::Function *IRGenModule::getAddrOfSILFunction(
   assert(forDefinition || !isDynamicallyReplaceableImplementation);
   assert(!forDefinition || !shouldCallPreviousImplementation);
 
+  PrettyStackTraceSILFunction entry("lowering address of", f);
   LinkEntity entity =
       LinkEntity::forSILFunction(f, shouldCallPreviousImplementation);
 

lib/IRGen/GenObjC.cpp

@@ -33,6 +33,7 @@
 #include "swift/ClangImporter/ClangImporter.h"
 #include "swift/Demangling/ManglingMacros.h"
 #include "swift/IRGen/Linking.h"
+#include "swift/SIL/PrettyStackTrace.h"
 #include "swift/SIL/SILModule.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclObjC.h"
@@ -779,6 +780,8 @@ Callee irgen::getObjCMethodCallee(IRGenFunction &IGF,
                                   llvm::Value *selfValue,
                                   CalleeInfo &&info) {
   SILDeclRef method = methodInfo.getMethod();
+  PrettyStackTraceSILDeclRef entry("lowering reference to ObjC method", method);
+
   // Note that isolated deallocator is never called directly, only from regular
   // deallocator
   assert((method.kind == SILDeclRef::Kind::Initializer

lib/IRGen/IRGenSIL.cpp

@@ -3117,6 +3117,8 @@ static bool mayDirectlyCallAsync(SILFunction *fn) {
 
 void IRGenSILFunction::visitFunctionRefBaseInst(FunctionRefBaseInst *i) {
   auto fn = i->getInitiallyReferencedFunction();
+  PrettyStackTraceSILFunction entry("lowering reference to", fn);
+
   auto fnType = fn->getLoweredFunctionType();
 
   auto fpKind = irgen::classifyFunctionPointerKind(fn);
@@ -8098,6 +8100,8 @@ void IRGenSILFunction::visitWitnessMethodInst(swift::WitnessMethodInst *i) {
   CanType baseTy = i->getLookupType();
   ProtocolConformanceRef conformance = i->getConformance();
   SILDeclRef member = i->getMember();
+  PrettyStackTraceSILDeclRef entry("lowering use of witness method", member);
+
   auto fnType = IGM.getSILTypes().getConstantFunctionType(
       IGM.getMaximalTypeExpansionContext(), member);
 
@@ -8282,6 +8286,7 @@ void IRGenSILFunction::visitSuperMethodInst(swift::SuperMethodInst *i) {
   llvm::Value *baseValue = base.claimNext();
 
   auto method = i->getMember().getOverriddenVTableEntry();
+  PrettyStackTraceSILDeclRef entry("lowering super call to", method);
   auto methodType = i->getType().castTo<SILFunctionType>();
 
   auto *classDecl = cast<ClassDecl>(method.getDecl()->getDeclContext());
@@ -8378,6 +8383,8 @@ void IRGenSILFunction::visitClassMethodInst(swift::ClassMethodInst *i) {
   llvm::Value *baseValue = base.claimNext();
 
   SILDeclRef method = i->getMember().getOverriddenVTableEntry();
+  PrettyStackTraceSILDeclRef entry("lowering class method call to", method);
+
   auto methodType = i->getType().castTo<SILFunctionType>();
 
   auto *classDecl = cast<ClassDecl>(method.getDecl()->getDeclContext());

lib/SIL/Utils/PrettyStackTrace.cpp

@@ -104,3 +104,9 @@ void PrettyStackTraceSILNode::print(llvm::raw_ostream &out) const {
   if (Node)
     out << *Node;
 }
+
+void PrettyStackTraceSILDeclRef::print(llvm::raw_ostream &out) const {
+  out << "While " << action << " SIL decl '";
+  declRef.print(out);
+  out << "'\n";
+}