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+//===---------------------------------------------------------------------===//
+// Random Notes
+//===---------------------------------------------------------------------===//
+
+C90/C99/C++ Comparisons:
+http://david.tribble.com/text/cdiffs.htm
+
+//===---------------------------------------------------------------------===//
+
+To time GCC preprocessing speed without output, use:
+ "time gcc -MM file"
+This is similar to -Eonly.
+
+//===---------------------------------------------------------------------===//
+
+Creating and using a PTH file for performance measurement (use a release build).
+
+$ clang -ccc-pch-is-pth -x objective-c-header INPUTS/Cocoa_h.m -o /tmp/tokencache
+$ clang -cc1 -token-cache /tmp/tokencache INPUTS/Cocoa_h.m
+
+//===---------------------------------------------------------------------===//
+
+ C++ Template Instantiation benchmark:
+ http://users.rcn.com/abrahams/instantiation_speed/index.html
+
+//===---------------------------------------------------------------------===//
+
+TODO: File Manager Speedup:
+
+ We currently do a lot of stat'ing for files that don't exist, particularly
+ when lots of -I paths exist (e.g. see the <iostream> example, check for
+ failures in stat in FileManager::getFile). It would be far better to make
+ the following changes:
+ 1. FileEntry contains a sys::Path instead of a std::string for Name.
+ 2. sys::Path contains timestamp and size, lazily computed. Eliminate from
+ FileEntry.
+ 3. File UIDs are created on request, not when files are opened.
+ These changes make it possible to efficiently have FileEntry objects for
+ files that exist on the file system, but have not been used yet.
+
+ Once this is done:
+ 1. DirectoryEntry gets a boolean value "has read entries". When false, not
+ all entries in the directory are in the file mgr, when true, they are.
+ 2. Instead of stat'ing the file in FileManager::getFile, check to see if
+ the dir has been read. If so, fail immediately, if not, read the dir,
+ then retry.
+ 3. Reading the dir uses the getdirentries syscall, creating an FileEntry
+ for all files found.
+
+//===---------------------------------------------------------------------===//
+// Specifying targets: -triple and -arch
+//===---------------------------------------------------------------------===//
+
+The clang supports "-triple" and "-arch" options. At most one -triple and one
+-arch option may be specified. Both are optional.
+
+The "selection of target" behavior is defined as follows:
+
+(1) If the user does not specify -triple, we default to the host triple.
+(2) If the user specifies a -arch, that overrides the arch in the host or
+ specified triple.
+
+//===---------------------------------------------------------------------===//
+
+
+verifyInputConstraint and verifyOutputConstraint should not return bool.
+
+Instead we should return something like:
+
+enum VerifyConstraintResult {
+ Valid,
+
+ // Output only
+ OutputOperandConstraintLacksEqualsCharacter,
+ MatchingConstraintNotValidInOutputOperand,
+
+ // Input only
+ InputOperandConstraintContainsEqualsCharacter,
+ MatchingConstraintReferencesInvalidOperandNumber,
+
+ // Both
+ PercentConstraintUsedWithLastOperand
+};
+
+//===---------------------------------------------------------------------===//
+
+Blocks should not capture variables that are only used in dead code.
+
+The rule that we came up with is that blocks are required to capture
+variables if they're referenced in evaluated code, even if that code
+doesn't actually rely on the value of the captured variable.
+
+For example, this requires a capture:
+ (void) var;
+But this does not:
+ if (false) puts(var);
+
+Summary of <rdar://problem/9851835>: if we implement this, we should
+warn about non-POD variables that are referenced but not captured, but
+only if the non-reachability is not due to macro or template
+metaprogramming.
+
+//===---------------------------------------------------------------------===//
+
+We can still apply a modified version of the constructor/destructor
+delegation optimization in cases of virtual inheritance where:
+ - there is no function-try-block,
+ - the constructor signature is not variadic, and
+ - the parameter variables can safely be copied and repassed
+ to the base constructor because either
+ - they have not had their addresses taken by the vbase initializers or
+ - they were passed indirectly.
+
+//===---------------------------------------------------------------------===//