зеркало из https://github.com/microsoft/clang-1.git
104 строки
3.8 KiB
Plaintext
104 строки
3.8 KiB
Plaintext
//===---------------------------------------------------------------------===//
|
|
// 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.
|
|
|
|
//===---------------------------------------------------------------------===//
|