assocFn -> derivativeFn everywhere except Differentiation.cpp.

[bgogul]

This PR contains refactoring changes related to https://bugs.swift.org/browse/TF-882. More PRs to come.

[bgogul]

@swift-ci please test tensorflow

[rxwei]

Thanks. There's also quite a lot of occurrences of "associated function". Could you replace them as well?

➜  swift git:(tensorflow) grep -rnw . -e 'associated function'
./test/AutoDiff/generics.swift:248:// TF-697: Test generic requirements of generated AD associated function.
./include/swift/SILOptimizer/Analysis/BottomUpIPAnalysis.h:46:  /// In the following "this function" refers to the associated function.
./include/swift/AST/Types.h:3103:  /// autodiff associated function.
./include/swift/AST/Types.h:3106:  /// indices include self, the computed associated function type will return a
./include/swift/AST/Types.h:3124:  /// Given the type of an autodiff associated function, returns the
./include/swift/AST/Types.h:3128:  /// Given the type of a transposing associated function, returns the
./include/swift/AST/DiagnosticsParse.def:1600:      "expected '{' to start an associated function list", ())
./include/swift/AST/DiagnosticsParse.def:1602:      "expected ',' between operands in an associated function list", ())
./include/swift/AST/DiagnosticsParse.def:1604:      "expected '}' to start an associated function list", ())
./include/swift/AST/DiagnosticsParse.def:1608:      "expected an associated function kind attribute, e.g. '[jvp]'", ())
./include/swift/AST/ASTMangler.h:158:  // Mangle the autodiff associated function (JVP/VJP) with the given:
./include/swift/AST/AutoDiff.h:434:/// The kind of an associated function.
./include/swift/AST/AutoDiff.h:455:/// autodiff associated function.
./include/swift/AST/AutoDiff.h:526:/// Computes the correct linkage for an associated function given the linkage of
./include/swift/SIL/SILDeclRef.h:160:  /// corresponding autodiff associated function.
./include/swift/SIL/SILDeclRef.h:366:  /// autodiff associated function.
./docs/SIL.rst:5640:In raw SIL, it is optional to provide an associated function ``with`` clause.
./docs/SIL.rst:5663:Extracts the original function or an associated function from the given
./lib/SILOptimizer/Mandatory/Differentiation.cpp:8704:    // Fold associated function extractors.
./lib/SILGen/SILGen.h:151:  /// Get or create an autodiff associated function thunk for the given
./lib/SILGen/SILGen.h:152:  /// SILDeclRef, SILFunction, and associated function type.
./lib/SILGen/SILGen.h:158:  /// Get or create an autodiff associated function vtable entry thunk for the
./lib/SILGen/SILGen.h:159:  /// given SILDeclRef and associated function type.
./lib/SILGen/SILGenBuiltin.cpp:1043:  // Get the associated function.
./lib/Sema/MiscDiagnostics.cpp:2251:/// from its associated function body.
./lib/Sema/TypeCheckAttr.cpp:2753:  // Returns true if the original function and associated function candidate are
./lib/Sema/TypeCheckAttr.cpp:2755:  // associated function have different parents, or if they both have no type
./lib/Sema/TypeCheckAttr.cpp:3596:  // Get derivative kind and associated function identifier.
./lib/ParseSIL/ParseSIL.cpp:2963:      // Parse associated function values as an operand list.
./lib/ParseSIL/ParseSIL.cpp:2965:      // we can infer AD associated function types.
./lib/ParseSIL/ParseSIL.cpp:3006:                     "associated function kind"))
./lib/AST/Builtins.cpp:1038:  // of the associated function type.
./lib/AST/Builtins.cpp:1045:  // Generator for the resultant function type, i.e. the AD associated function.
./lib/AST/Attr.cpp:523:  // Print associated function names, unless they are to be omitted.
./lib/AST/AutoDiff.cpp:168:  // associated function. Return the linkage of the original function, unless
./lib/AST/AutoDiff.cpp:169:  // the associated function is not exported (i.e. differentiation is not
./lib/AST/AutoDiff.cpp:179:  // function. Make the associated function hidden.
./lib/AST/Type.cpp:4680:  // Wrap the associated function type in additional curry levels.
./lib/AST/Type.cpp:4719:  // Wrap the associated function type in additional curry levels.
./lib/SIL/SILFunctionType.cpp:153:// Returns the canonical generic signature for an autodiff associated function
./lib/SIL/SILFunctionType.cpp:154:// given an existing associated function generic signature. All differentiation
./lib/SIL/SILFunctionType.cpp:165:  // Add associated function generic signature.
./lib/SIL/SILFunctionType.cpp:205:  // Get the canonical associated function generic signature.
./lib/SIL/SILFunctionType.cpp:2337:  // determine `silFnType` by first computing the associated function type at
./lib/SIL/SILFunctionType.cpp:2340:  // function's AST type, and then computing the associated function type at the

[rxwei]

Suggested change

	getOpValue(Inst->getVJPFunction()));
	getOpValue(Inst->getVJPFunction()));

[rxwei]

I'll merge this and address my comments in a different patch, since you are OOO today. Thanks!