Profiling a basic internal real input read benchmark shows some
hot spots in the code used to prepare input for decimal-to-binary
conversion, which is of course where the time should be spent.
The library that implements decimal to/from binary conversions has
been optimized, but not the code in the Fortran runtime that calls it,
and there are some obvious light changes worth making here.
Move some member functions from *.cpp files into the class definitions
of Descriptor and IoStatementState to enable inlining and specialization.
Make GetNextInputBytes() the new basic input API within the
runtime, replacing GetCurrentChar() -- which is rewritten in terms of
GetNextInputBytes -- so that input routines can have the
ability to acquire more than one input character at a time
and amortize overhead.
These changes speed up the time to read 1M random reals
using internal I/O from a character array from 1.29s to 0.54s
on my machine, which on par with Intel Fortran and much faster than
GNU Fortran.
Differential Revision: https://reviews.llvm.org/D113697
Tweak binary->decimal conversions to avoid an integer multiplication
in a hot loop to improve readability and get a minor (~5%) speed-up.
Use native integer division by constants for more readability, too,
since current build compilers seem to optimize it correctly now.
Delete the now needless temporary work-around facility in
Common/unsigned-const-division.h.
Differential revision: https://reviews.llvm.org/D88604
Use short division of big-radix values by powers of two when
converting values with negative unbiased exponents rather than
multiplication by smaller powers of five; this reduces the overall
outer iteration count. This change is a win across the entire range
of inputs.
Reviewed By: tskeith
Differential Revision: https://reviews.llvm.org/D83806
There were dependences upon LLVM libraries in the Fortran
runtime support library binaries due to some indirect #includes
of llvm/Support/raw_ostream.h, which caused some kind of internal
ABI version consistency checking to get pulled in. Fixed by
cleaning up some includes.
Reviewed By: tskeith, PeteSteinfeld, sscalpone
Differential Revision: https://reviews.llvm.org/D83060
Summary: Apply workaround done in D81179 only for GCC < 8. As @klausler mentioned in D81179 we want to avoid additional checks for other compilers that do not need them.
Reviewers: DavidTruby, klausler, jdoerfert, sscalpone
Reviewed By: klausler, sscalpone
Subscribers: llvm-commits, tskeith, isuruf, klausler
Tags: #flang, #llvm
Differential Revision: https://reviews.llvm.org/D81208
Summary:
Fix decimal formatting of 80-bit x87 values; the calculation ofnearest neighbor values failed to account for the explicitmost significant bit in that format.
Replace MultiplyByRounded with MultiplyBy in binary->decimal conversions,
since rounding won't happen and the name was misleading; then remove
dead code, and migrate LoseLeastSignificantDigit() from one source file
to another where it's still needed.
Reviewers: tskeith, sscalpone, jdoerfert, DavidTruby
Reviewed By: tskeith
Subscribers: llvm-commits, flang-commits
Tags: #flang, #llvm
Differential Revision: https://reviews.llvm.org/D79345
Peter Klausler