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Diffstat (limited to 'clang/NOTES.txt')
| -rw-r--r-- | clang/NOTES.txt | 136 |
1 files changed, 0 insertions, 136 deletions
diff --git a/clang/NOTES.txt b/clang/NOTES.txt deleted file mode 100644 index 0759acf..0000000 --- a/clang/NOTES.txt +++ /dev/null @@ -1,136 +0,0 @@ -//===---------------------------------------------------------------------===// -// 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. - - -//===---------------------------------------------------------------------===// - - 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. - -//===---------------------------------------------------------------------===// - -TODO: Fast #Import: - - * Get frameworks that don't use #import to do so, e.g. - DirectoryService, AudioToolbox, CoreFoundation, etc. Why not using #import? - Because they work in C mode? C has #import. - * Have the lexer return a token for #import instead of handling it itself. - - Create a new preprocessor object with no external state (no -D/U options - from the command line, etc). Alternatively, keep track of exactly which - external state is used by a #import: declare it somehow. - * When having reading a #import file, keep track of whether we have (and/or - which) seen any "configuration" macros. Various cases: - - Uses of target args (__POWERPC__, __i386): Header has to be parsed - multiple times, per-target. What about #ifndef checks? How do we know? - - "Configuration" preprocessor macros not defined: POWERPC, etc. What about - things like __STDC__ etc? What is and what isn't allowed. - * Special handling for "umbrella" headers, which just contain #import stmts: - - Cocoa.h/AppKit.h - Contain pointers to digests instead of entire digests - themselves? Foundation.h isn't pure umbrella! - * Frameworks digests: - - Can put "digest" of a framework-worth of headers into the framework - itself. To open AppKit, just mmap - /System/Library/Frameworks/AppKit.framework/"digest", which provides a - symbol table in a well defined format. Lazily unstream stuff that is - needed. Contains declarations, macros, and debug information. - - System frameworks ship with digests. How do we handle configuration - information? How do we handle stuff like: - #if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_2 - which guards a bunch of decls? Should there be a couple of default - configs, then have the UI fall back to building/caching its own? - - GUI automatically builds digests when UI is idle, both of system - frameworks if they aren't not available in the right config, and of app - frameworks. - - GUI builds dependence graph of frameworks/digests based on #imports. If a - digest is out date, dependent digests are automatically invalidated. - - * New constraints on #import for objc-v3: - - #imported file must not define non-inline function bodies. - - Alternatively, they can, and these bodies get compiled/linked *once* - per app into a dylib. What about building user dylibs? - - Restrictions on ObjC grammar: can't #import the body of a for stmt or fn. - - Compiler must detect and reject these cases. - - #defines defined within a #import have two behaviors: - - By default, they escape the header. These macros *cannot* be #undef'd - by other code: this is enforced by the front-end. - - Optionally, user can specify what macros escape (whitelist) or can use - #undef. - -//===---------------------------------------------------------------------===// - -TODO: New language feature: Configuration queries: - - Instead of #ifdef __POWERPC__, use "if (strcmp(`cpu`, __POWERPC__))", or - some other, better, syntax. - - Use it to increase the number of "architecture-clean" #import'd files, - allowing a single index to be used for all fat slices. - -//===---------------------------------------------------------------------===// -// 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 -}; - -//===---------------------------------------------------------------------===// |