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| author | Justin Lebar <jlebar@google.com> | 2016-05-20 21:33:01 +0000 |
|---|---|---|
| committer | Justin Lebar <jlebar@google.com> | 2016-05-20 21:33:01 +0000 |
| commit | f83d52142acb65b41010b6f8fcf006cba65429e1 (patch) | |
| tree | 3f9732c7d242b554af55744bde04eddd06168843 /docs/UsersManual.rst | |
| parent | 5c2e21d12f6ff7d763c7aa057b6ed36b1081ce57 (diff) | |
Update -ffast-math documentation to match reality.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D20457
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@270279 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/UsersManual.rst')
| -rw-r--r-- | docs/UsersManual.rst | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst index 48a85a6ccb..b88a418d89 100644 --- a/docs/UsersManual.rst +++ b/docs/UsersManual.rst @@ -1055,6 +1055,19 @@ are listed below. the behavior of sanitizers in the ``cfi`` group to allow checking of cross-DSO virtual and indirect calls. +.. option:: -ffast-math + + Enable fast-math mode. This defines the ``__FAST_MATH__`` preprocessor + macro, and lets the compiler make aggressive, potentially-lossy assumptions + about floating-point math. These include: + + * Floating-point math obeys regular algebraic rules for real numbers (e.g. + ``+`` and ``*`` are associative, ``x/y == x * (1/y)``, and + ``(a + b) * c == a * c + b * c``), + * operands to floating-point operations are not equal to ``NaN`` and + ``Inf``, and + * ``+0`` and ``-0`` are interchangeable. + .. option:: -fwhole-program-vtables Enable whole-program vtable optimizations, such as single-implementation |