The nan family of math routines do not rely on global state. They do
however depend on their parameter. This fits the description of pure:
Functions which have no effects except the return value and their
return value depends only on the parameters and/or global variables.
Mark the family as `readonly`.
llvm-svn: 315968
The `nan` family of functions will inspect the contents of the parameter
that they are passed. As a result, the function cannot be annotated as
`const`. The documentation of the `const` attribute explicitly states
this:
Note that a function that has pointer arguments and examines the data
pointed to must not be declared const.
Adjust the annotations on this family of functions.
llvm-svn: 315741
Summary:
POSIX requires lgamma writes to an external global variable, signgam.
This prevents annotating lgamma with readnone, which is incorrect on
targets that write to signgam.
Reviewers: efriedma, rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D29778
llvm-svn: 295781
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
Sanjay Patel