[libc-commits] [PATCH] D150399: [libc] add options to printf decimal floats

[Michael Jones via Phabricator via libc-commits]

michaelrj added inline comments.


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Comment at: libc/src/__support/float_to_string.h:144
+  constexpr cpp::UInt<INT_SIZE> MOD_SIZE =
+      (cpp::UInt<INT_SIZE>(1000000000)
+       << (CALC_SHIFT_CONST + (IDX_SIZE > 1 ? IDX_SIZE : 0)));
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lntue wrote:
> I'm just curious, will changing from `1000000000 * 2^(...)` to `1953125 * 2^(... + 9)` has any affect, like performance or accuracy?  Same with other instances below.
This number is constexpr, so there should be no change.


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Comment at: libc/src/__support/float_to_string.h:603-608
+  // const int idx = -exponent / IDX_SIZE;
+  // constexpr int idx_min = (IDX_SIZE / 4) + 1;
+  // if (idx < idx_min) {
+  //   return 0;
+  // }
+  // return static_cast<size_t>(idx - idx_min) / 2;
----------------
lntue wrote:
> Are those still relevant?
I need to see if I can fix their calculations to make them work, but they should speed up the int mode.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150399/new/

https://reviews.llvm.org/D150399