Use compiler builtins to detect "simple common cases" in pp_add, pp_subtract, and pp_multiply #23503
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This will hopefully make the code faster and smaller, and
make more cases to be handled as "simple common cases".
Note that this change uses HAS_BUILTIN_{ADD,SUB,MUL}_OVERFLOW macros
which have already been defined in config.h but seem not to have been
used by existing code.
t/op/64bitint.t: Add tests to exercise "simple common cases".
Note that these tests should pass even before this change.
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This breaks Win32, which doesn't enable the I suspect it's due to |
… in UV If C compiler doesn't know __builtin_mul_overflow, S_uv_mul_overflow will be implemented with fallback "long multiplication" algorithm, but it had a bug that elemental multiplications were done in unsigned long precision instead of UV precision. It will lead wrong result when unsigned long is narrower than UV (for example -Duse64bitint on 32-bit platform).
Thank you for your comment. My patch has a fallback code (similar to the code used before this change) for compilers with no overflow-checking builtins, but it had a bug (I was able to reproduce similar symptoms by |
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This will hopefully make the code faster and smaller, and make more cases to be handled as "simple common cases".
Note that this change uses
HAS_BUILTIN_{ADD,SUB,MUL}_OVERFLOWmacros which have already been defined inconfig.hbut seem not to have been used by existing code.The behavior should be the same before and after this change.