These functions have the same constness properties of the normal libm
functions, which allows LLVM to optimise code better in general. There
are also a couple of specific optimisations that only trigger when
these are properly marked.
rdar://problem/13729466
llvm-svn: 199249
For all libm __builtin_* functions that are defined, this adds the
corresponding LIBBUILTIN definitions (tagged, as necessary, with "e" instead of
"c" when the function may set errno).
Note that this changes the current definitions for lrint and fma
(unfortunately). The Linux man page documents that these don't set errno, but
the POSIX standard says that they should.
llvm-svn: 190922
The libm math functions should be marked with the "n" (nothrow) flag so that
the corresponding IR function declarations are tagged with the nounwind
attribute (this has been true in C mode, but not in C++ mode).
The test case has been updated to run in C++ mode in addition to in C mode.
llvm-svn: 190217
The conditions described by POSIX can never happen with IEEE-754 floats.
When the function is const we can emit a single sse4.1 instruction for
it, without losing anything :)
llvm-svn: 162379
There were missed optimizations when the system headers didn't have attributes
in place, specifically:
- Add copysign, exp2, log2, nearbyint, rint and trunc to the list.
These are functions that get inlined by LLVM's optimizer, but only when they
have the right attributes.
- Mark copysign, fabs, fmax, fmin and trunc const unconditionally.
Previously these were only const with -fno-math-errno, but they never set
errno per POSIX.
For ceil/floor/nearbyint/round I'm not aware of any implementation that sets
errno, but POSIX says it may signal overflow so I left them alone for now.
llvm-svn: 162375
Tim Northover