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Make skip_double() comment more explicit

This commit is contained in:
John Keiser 2020-08-18 10:16:08 -07:00
parent 988c62baed
commit 9b11e119d4
1 changed files with 10 additions and 4 deletions
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14
src/generic/stage2/numberparsing.h
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@ -370,9 +370,12 @@ simdjson_really_inline error_code write_float(const uint8_t *const src, bool neg
// 10000000000000000000000000000000000000000000e+308 // 10000000000000000000000000000000000000000000e+308
// 3.1415926535897932384626433832795028841971693993751 // 3.1415926535897932384626433832795028841971693993751
// //
// NOTE: This makes a *copy* of the writer and passes it to slow_float_parsing. This happens
// because slow_float_parsing is a non-inlined function. If we passed our writer reference to
// it, it would force it to be stored in memory, preventing the compiler from picking it apart
// and putting into registers. i.e. if we pass it as reference, it gets slow.
// This is what forces the skip_double, as well.
error_code error = slow_float_parsing(src, writer); error_code error = slow_float_parsing(src, writer);
// The number was already written, but we made a copy of the writer
// when we passed it to the parse_large_integer() function, so
writer.skip_double(); writer.skip_double();
return error; return error;
} }
@ -382,9 +385,12 @@ simdjson_really_inline error_code write_float(const uint8_t *const src, bool neg
if (simdjson_unlikely(exponent < FASTFLOAT_SMALLEST_POWER) || (exponent > FASTFLOAT_LARGEST_POWER)) { if (simdjson_unlikely(exponent < FASTFLOAT_SMALLEST_POWER) || (exponent > FASTFLOAT_LARGEST_POWER)) {
// this is almost never going to get called!!! // this is almost never going to get called!!!
// we start anew, going slowly!!! // we start anew, going slowly!!!
// NOTE: This makes a *copy* of the writer and passes it to slow_float_parsing. This happens
// because slow_float_parsing is a non-inlined function. If we passed our writer reference to
// it, it would force it to be stored in memory, preventing the compiler from picking it apart
// and putting into registers. i.e. if we pass it as reference, it gets slow.
// This is what forces the skip_double, as well.
error_code error = slow_float_parsing(src, writer); error_code error = slow_float_parsing(src, writer);
// The number was already written, but we made a copy of the writer when we passed it to the
// slow_float_parsing() function, so we have to skip those tape spots now that we've returned
writer.skip_double(); writer.skip_double();
return error; return error;
} }