| 1 | // mycpp/common.h
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| 2 | //
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| 3 | // A grab bag of definitions needed in multiple places.
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| 4 | 
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| 5 | #ifndef COMMON_H
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| 6 | #define COMMON_H
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| 7 | 
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| 8 | #include <assert.h>  // assert()
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| 9 | #include <stdarg.h>  // va_list, etc.
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| 10 | #include <stddef.h>  // max_align_t
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| 11 | #include <stdio.h>   // vprintf
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| 12 | 
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| 13 | // opt variants pass -D OPTIMIZED
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| 14 | #ifdef OPTIMIZED
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| 15 |   #define DCHECK(cond)
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| 16 | #else
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| 17 |   #define DCHECK(cond) assert(cond)
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| 18 | #endif
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| 19 | 
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| 20 | // TODO: all assert() should be DCHECK() or CHECK()
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| 21 | #define CHECK(cond) assert(cond)
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| 22 | 
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| 23 | #define FAIL(reason) assert(false)
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| 24 | 
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| 25 | enum Reason { kShouldNotGetHere, kNotImplemented };
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| 26 | 
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| 27 | // Workaround for macros that take templates
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| 28 | #define COMMA ,
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| 29 | 
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| 30 | // Prevent silent copies
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| 31 | #define DISALLOW_COPY_AND_ASSIGN(TypeName) \
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| 32 |   TypeName(TypeName&) = delete;            \
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| 33 |   void operator=(TypeName) = delete;
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| 34 | 
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| 35 | // log() is for hand-written code, not generated
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| 36 | 
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| 37 | inline void log(const char* fmt, ...) {
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| 38 |   va_list args;
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| 39 |   va_start(args, fmt);
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| 40 |   vfprintf(stderr, fmt, args);
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| 41 |   va_end(args);
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| 42 |   fputs("\n", stderr);
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| 43 | }
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| 44 | 
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| 45 | // I'm not sure why this matters but we get crashes when aligning to 8 bytes.
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| 46 | // That is annoying.
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| 47 | // Example: we get a crash in cpp/frontend_flag_spec.cc
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| 48 | // auto out = new flag_spec::_FlagSpecAndMore();
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| 49 | //
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| 50 | // https://stackoverflow.com/questions/52531695/int128-alignment-segment-fault-with-gcc-o-sse-optimize
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| 51 | constexpr int kMask = alignof(max_align_t) - 1;  // e.g. 15 or 7
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| 52 | 
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| 53 | // Align returned pointers to the worst case of 8 bytes (64-bit pointers)
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| 54 | inline size_t aligned(size_t n) {
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| 55 |   // https://stackoverflow.com/questions/2022179/c-quick-calculation-of-next-multiple-of-4
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| 56 |   // return (n + 7) & ~7;
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| 57 |   return (n + kMask) & ~kMask;
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| 58 | }
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| 59 | 
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| 60 | #define KiB(bytes) ((bytes)*1024)
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| 61 | #define MiB(bytes) (KiB(bytes) * 1024)
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| 62 | #define GiB(bytes) (MiB(bytes) * 1024)
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| 63 | 
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| 64 | const int kMaxRoots = KiB(4);
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| 65 | 
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| 66 | // Used by both Str and List slicing.  3 adjustments:
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| 67 | // 1. begin: negative, or greater than len
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| 68 | // 2. end: negative, or greater than len
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| 69 | // 3. begin > end means empty slice
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| 70 | 
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| 71 | #define SLICE_ADJUST(begin, end, len) \
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| 72 |   if (begin < 0) {                    \
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| 73 |     begin += len;                     \
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| 74 |     if (begin < 0) {                  \
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| 75 |       begin = 0;                      \
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| 76 |     }                                 \
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| 77 |   } else if (begin > len) {           \
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| 78 |     begin = len;                      \
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| 79 |   }                                   \
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| 80 |   if (end < 0) {                      \
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| 81 |     end += len;                       \
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| 82 |     if (end < 0) {                    \
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| 83 |       end = 0;                        \
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| 84 |     }                                 \
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| 85 |   } else if (end > len) {             \
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| 86 |     end = len;                        \
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| 87 |   }                                   \
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| 88 |   if (begin > end) {                  \
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| 89 |     end = begin;                      \
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| 90 |   }
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| 91 | 
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| 92 | #endif  // COMMON_H
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