[IRGen][runtime] Simplify runtime CCs and entry point ABIs

include/swift/Runtime/Casting.h

@@ -37,13 +37,12 @@ namespace swift {
 ///
 /// \return true if the cast succeeded. Depending on the flags,
 ///   swift_dynamicCast may fail rather than return false.
-SWIFT_RT_ENTRY_VISIBILITY
+SWIFT_RUNTIME_EXPORT
 bool
 swift_dynamicCast(OpaqueValue *dest, OpaqueValue *src,
                   const Metadata *srcType,
                   const Metadata *targetType,
-                  DynamicCastFlags flags)
-    SWIFT_CC(RegisterPreservingCC);
+                  DynamicCastFlags flags);
 
 /// \brief Checked dynamic cast to a Swift class type.
 ///
@@ -52,10 +51,9 @@ swift_dynamicCast(OpaqueValue *dest, OpaqueValue *src,
 /// a Swift class type.
 ///
 /// \returns the object if the cast succeeds, or null otherwise.
-SWIFT_RT_ENTRY_VISIBILITY
+SWIFT_RUNTIME_EXPORT
 const void *
-swift_dynamicCastClass(const void *object, const ClassMetadata *targetType)
-    SWIFT_CC(RegisterPreservingCC);
+swift_dynamicCastClass(const void *object, const ClassMetadata *targetType);
 
 /// \brief Unconditional, checked dynamic cast to a Swift class type.
 ///

include/swift/Runtime/Config.h

@@ -96,14 +96,14 @@
 // Annotation for specifying a calling convention of
 // a runtime function. It should be used with declarations
 // of runtime functions like this:
-// void runtime_function_name() SWIFT_CC(RegisterPreservingCC)
+// void runtime_function_name() SWIFT_CC(swift)
 #define SWIFT_CC(CC) SWIFT_CC_##CC
 
-#define SWIFT_CC_preserve_most __attribute__((preserve_most))
-#define SWIFT_CC_preserve_all  __attribute__((preserve_all))
+// SWIFT_CC(c) is the C calling convention.
 #define SWIFT_CC_c
 
-// Define SWIFT_CC_swift in terms of the Swift CC for runtime functions.
+// SWIFT_CC(swift) is the Swift calling convention.
+// FIXME: the next comment is false.
 // Functions outside the stdlib or runtime that include this file may be built 
 // with a compiler that doesn't support swiftcall; don't define these macros
 // in that case so any incorrect usage is caught.
@@ -119,133 +119,21 @@
 #define SWIFT_INDIRECT_RESULT
 #endif
 
-#define SWIFT_CC_SwiftCC SWIFT_CC_swift
-
-// Map a logical calling convention (e.g. RegisterPreservingCC) to LLVM calling
-// convention.
-#define SWIFT_LLVM_CC(CC) SWIFT_LLVM_CC_##CC
-
-// Currently, RuntimeFunction.def uses the following calling conventions:
-// DefaultCC, RegisterPreservingCC.
-// If new runtime calling conventions are added later, they need to be mapped
-// here to something appropriate.
-
-// DefaultCC is usually the standard C calling convention.
-#define SWIFT_CC_DefaultCC SWIFT_CC_c
-#define SWIFT_CC_DefaultCC_IMPL SWIFT_CC_c
-#define SWIFT_LLVM_CC_DefaultCC llvm::CallingConv::C
-
-#define SWIFT_LLVM_CC_RegisterPreservingCC llvm::CallingConv::PreserveMost
-
-#define SWIFT_LLVM_CC_SwiftCC llvm::CallingConv::Swift
-
-// If defined, it indicates that runtime function wrappers
-// should be used on all platforms, even they do not support
-// the new calling convention which requires this.
-#define SWIFT_RT_USE_WRAPPERS_ALWAYS 1
-
-// If defined, it indicates that this calling convention is
-// supported by the current target.
-// TODO: Define it once the runtime calling convention support has
-// been integrated into clang and llvm.
-#define SWIFT_RT_USE_RegisterPreservingCC 0
-
-#if  __has_attribute(preserve_most)
-#define SWIFT_BACKEND_SUPPORTS_RegisterPreservingCC 1
-#else
-#define SWIFT_BACKEND_SUPPORTS_RegisterPreservingCC 0
-#endif
-
-
-// RegisterPreservingCC is a dedicated runtime calling convention to be used
-// when calling the most popular runtime functions.
-#if SWIFT_RT_USE_RegisterPreservingCC &&                              \
-    SWIFT_BACKEND_SUPPORTS_RegisterPreservingCC && defined(__aarch64__)
-// Targets supporting the dedicated runtime convention should use it.
-// If a runtime function is using this calling convention, it can
-// be invoked only by means of a wrapper, which performs an indirect
-// call. Wrappers are generated by the IRGen and added to object files.
-// As a result, runtime functions are invoked only indirectly from
-// the user code.
-// This is a workaround for dynamic linking issues, where a dynamic
-// linker may clobber some of the callee-saved registers defined by
-// this new calling convention when it performs lazy binding of
-// runtime functions using this new calling convention.
-#define SWIFT_CC_RegisterPreservingCC                          \
-  SWIFT_CC_preserve_most
-#define SWIFT_CC_RegisterPreservingCC_IMPL                     \
-  SWIFT_CC_preserve_most
-
-// Indicate that wrappers should be used, because it is required
-// for the calling convention to get around dynamic linking issues.
-#define SWIFT_RT_USE_WRAPPERS 1
-
-#else
-
-// Targets not supporting the dedicated runtime calling convention
-// should use the standard calling convention instead.
-// No wrappers are required in this case by the calling convention.
-#define SWIFT_CC_RegisterPreservingCC SWIFT_CC_c
-#define SWIFT_CC_RegisterPreservingCC_IMPL SWIFT_CC_c
-
-#endif
-
-// The runtime implementation uses the preserve_most convention to save
-// registers spills on the hot path.
+// SWIFT_CC(PreserveMost) is used in the runtime implementation to prevent
+// register spills on the hot path.
+// It is not safe to use for external calls; the loader's lazy function
+// binding may not save all of the registers required for this convention.
 #if __has_attribute(preserve_most) &&                                          \
     (defined(__aarch64__) || defined(__x86_64__))
 #define SWIFT_CC_PreserveMost __attribute__((preserve_most))
 #else
 #define SWIFT_CC_PreserveMost
 #endif
 
-// Generates a name of the runtime entry's implementation by
-// adding an underscore as a prefix and a suffix.
-#define SWIFT_RT_ENTRY_IMPL(Name) _##Name##_
-
-// Library internal way to invoke the implementation of a runtime entry.
-// E.g. a runtime function may be called internally via its public API
-// or via the function pointer.
-#define SWIFT_RT_ENTRY_CALL(Name) Name
-
-// Name of the symbol holding a reference to the
-// implementation of a runtime entry.
-#define SWIFT_RT_ENTRY_REF(Name) _##Name
-
-// String representation of the symbol's name.
-#define SWIFT_RT_ENTRY_REF_AS_STR(Name) "_" #Name
-
-#if defined(SWIFT_RT_USE_WRAPPERS_ALWAYS)
-#undef SWIFT_RT_USE_WRAPPERS
-#define SWIFT_RT_USE_WRAPPERS
-#endif
-
-#if defined(SWIFT_RT_USE_WRAPPERS)
-
-// Both the runtime functions and their implementation are hidden and
-// can be directly referenced only inside the runtime library.
-// User code can access these runtime entries only indirectly
-// via a global function pointer.
-// NOTE: In principle, entries may have LLVM_LIBRARY_VISIBILITY,
-// because they are never called directly from the code
-// produced by IRGen.
-// But some of the runtime entries are invoked directly from
-// the foundation. Therefore they should be visible.
-#define SWIFT_RT_ENTRY_VISIBILITY SWIFT_RUNTIME_EXPORT
-#define SWIFT_RT_ENTRY_IMPL_VISIBILITY LLVM_LIBRARY_VISIBILITY
-
-// Prefix of wrappers generated for runtime functions.
-#define SWIFT_WRAPPER_PREFIX "swift_rt_"
-
-#else
-
-// Runtime functions are exported, because it should be possible
-// to invoke them directly from the user code. But internal
-// implementations of runtime functions do not need to be exported.
-#define SWIFT_RT_ENTRY_VISIBILITY SWIFT_RUNTIME_EXPORT
-#define SWIFT_RT_ENTRY_IMPL_VISIBILITY LLVM_LIBRARY_VISIBILITY
-
-#endif
+// This is the DefaultCC value used by the compiler.
+// FIXME: the runtime's code does not honor DefaultCC
+// so changing this value is not sufficient.
+#define SWIFT_DEFAULT_LLVM_CC llvm::CallingConv::C
 
 // These are temporary macros during the +0 cc exploration to cleanly support
 // both +0 and +1 in the runtime.

include/swift/Runtime/Enum.h

@@ -67,12 +67,10 @@ void swift_initEnumMetadataSinglePayload(EnumMetadata *enumType,
 /// \returns -1 if the payload case is inhabited. If an empty case is inhabited,
 ///          returns a value greater than or equal to zero and less than
 ///          emptyCases.
-SWIFT_RT_ENTRY_VISIBILITY
+SWIFT_RUNTIME_EXPORT
 int swift_getEnumCaseSinglePayload(const OpaqueValue *value,
                                    const Metadata *payload,
-                                   unsigned emptyCases)
-  SWIFT_CC(RegisterPreservingCC);
-
+                                   unsigned emptyCases);
 
 
 /// \brief Store the tag value for the given case into a single-payload enum,
@@ -86,12 +84,11 @@ int swift_getEnumCaseSinglePayload(const OpaqueValue *value,
 ///                    case, or a value greater than or equal to zero and less
 ///                    than emptyCases for an empty case.
 /// \param emptyCases - the number of empty cases in the enum.
-SWIFT_RT_ENTRY_VISIBILITY
+SWIFT_RUNTIME_EXPORT
 void swift_storeEnumTagSinglePayload(OpaqueValue *value,
                                      const Metadata *payload,
                                      int whichCase,
-                                     unsigned emptyCases)
-  SWIFT_CC(RegisterPreservingCC);
+                                     unsigned emptyCases);
 
 /// \brief Initialize the type metadata for a generic, multi-payload
 ///        enum instance.