| 1 | //===---------------------------------------------------------------------===// |
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| 2 | // Random Notes |
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| 3 | //===---------------------------------------------------------------------===// |
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| 4 | |
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| 5 | //===---------------------------------------------------------------------===// |
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| 6 | |
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| 7 | To time GCC preprocessing speed without output, use: |
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| 8 | "time gcc -MM file" |
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| 9 | This is similar to -Eonly. |
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| 10 | |
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| 11 | //===---------------------------------------------------------------------===// |
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| 12 | |
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| 13 | C++ Template Instantiation benchmark: |
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| 14 | http://users.rcn.com/abrahams/instantiation_speed/index.html |
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| 15 | |
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| 16 | //===---------------------------------------------------------------------===// |
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| 17 | |
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| 18 | TODO: File Manager Speedup: |
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| 19 | |
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| 20 | We currently do a lot of stat'ing for files that don't exist, particularly |
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| 21 | when lots of -I paths exist (e.g. see the <iostream> example, check for |
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| 22 | failures in stat in FileManager::getFile). It would be far better to make |
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| 23 | the following changes: |
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| 24 | 1. FileEntry contains a sys::Path instead of a std::string for Name. |
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| 25 | 2. sys::Path contains timestamp and size, lazily computed. Eliminate from |
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| 26 | FileEntry. |
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| 27 | 3. File UIDs are created on request, not when files are opened. |
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| 28 | These changes make it possible to efficiently have FileEntry objects for |
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| 29 | files that exist on the file system, but have not been used yet. |
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| 30 | |
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| 31 | Once this is done: |
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| 32 | 1. DirectoryEntry gets a boolean value "has read entries". When false, not |
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| 33 | all entries in the directory are in the file mgr, when true, they are. |
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| 34 | 2. Instead of stat'ing the file in FileManager::getFile, check to see if |
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| 35 | the dir has been read. If so, fail immediately, if not, read the dir, |
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| 36 | then retry. |
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| 37 | 3. Reading the dir uses the getdirentries syscall, creating a FileEntry |
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| 38 | for all files found. |
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| 39 | |
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| 40 | //===---------------------------------------------------------------------===// |
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| 41 | // Specifying targets: -triple and -arch |
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| 42 | //===---------------------------------------------------------------------===// |
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| 43 | |
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| 44 | The clang supports "-triple" and "-arch" options. At most one -triple and one |
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| 45 | -arch option may be specified. Both are optional. |
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| 46 | |
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| 47 | The "selection of target" behavior is defined as follows: |
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| 48 | |
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| 49 | (1) If the user does not specify -triple, we default to the host triple. |
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| 50 | (2) If the user specifies a -arch, that overrides the arch in the host or |
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| 51 | specified triple. |
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| 52 | |
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| 53 | //===---------------------------------------------------------------------===// |
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| 54 | |
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| 55 | |
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| 56 | verifyInputConstraint and verifyOutputConstraint should not return bool. |
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| 57 | |
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| 58 | Instead we should return something like: |
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| 59 | |
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| 60 | enum VerifyConstraintResult { |
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| 61 | Valid, |
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| 62 | |
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| 63 | // Output only |
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| 64 | OutputOperandConstraintLacksEqualsCharacter, |
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| 65 | MatchingConstraintNotValidInOutputOperand, |
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| 66 | |
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| 67 | // Input only |
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| 68 | InputOperandConstraintContainsEqualsCharacter, |
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| 69 | MatchingConstraintReferencesInvalidOperandNumber, |
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| 70 | |
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| 71 | // Both |
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| 72 | PercentConstraintUsedWithLastOperand |
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| 73 | }; |
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| 74 | |
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| 75 | //===---------------------------------------------------------------------===// |
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| 76 | |
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| 77 | Blocks should not capture variables that are only used in dead code. |
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| 78 | |
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| 79 | The rule that we came up with is that blocks are required to capture |
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| 80 | variables if they're referenced in evaluated code, even if that code |
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| 81 | doesn't actually rely on the value of the captured variable. |
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| 82 | |
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| 83 | For example, this requires a capture: |
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| 84 | (void) var; |
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| 85 | But this does not: |
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| 86 | if (false) puts(var); |
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| 87 | |
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| 88 | Summary of <rdar://problem/9851835>: if we implement this, we should |
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| 89 | warn about non-POD variables that are referenced but not captured, but |
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| 90 | only if the non-reachability is not due to macro or template |
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| 91 | metaprogramming. |
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| 92 | |
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| 93 | //===---------------------------------------------------------------------===// |
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| 94 | |
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| 95 | We can still apply a modified version of the constructor/destructor |
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| 96 | delegation optimization in cases of virtual inheritance where: |
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| 97 | - there is no function-try-block, |
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| 98 | - the constructor signature is not variadic, and |
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| 99 | - the parameter variables can safely be copied and repassed |
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| 100 | to the base constructor because either |
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| 101 | - they have not had their addresses taken by the vbase initializers or |
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| 102 | - they were passed indirectly. |
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| 103 | |
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| 104 | //===---------------------------------------------------------------------===// |
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| 105 | |
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