diff options
Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 0b6644b..020442a 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -2199,6 +2199,7 @@ those that have already been displayed. If @option{--help} is also specified anywhere on the command line then this takes precedence over any @option{--help=} option. +@opindex Q If the @option{-Q} option appears on the command line before the @option{--help=} option, then the descriptive text displayed by @option{--help=} is changed. Instead of describing the displayed @@ -14648,12 +14649,14 @@ Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}. @item -fstrict-aliasing Allow the compiler to assume the strictest aliasing rules applicable to the language being compiled. For C (and C++), this activates -optimizations based on the type of expressions. In particular, an -object of one type is assumed never to reside at the same address as an -object of a different type, unless the types are almost the same. For -example, an @code{unsigned int} can alias an @code{int}, but not a -@code{void*} or a @code{double}. A character type may alias any other -type. +optimizations based on the type of expressions. In particular, accessing +an object of one type via an expression of a different type is not allowed, +unless the types are @dfn{compatible types}, differ only in signedness or +qualifiers, or the expression has a character type. Accessing scalar +objects via a corresponding vector type is also allowed. + +For example, an @code{unsigned int} can alias an @code{int}, but not a +@code{void*} or a @code{double}. A character type may alias any other type. @anchor{Type-punning}Pay special attention to code like this: @smallexample @@ -21311,8 +21314,13 @@ Toggle @option{-fvar-tracking-assignments}, in the same way that @opindex Q @item -Q -Makes the compiler print out each function name as it is compiled, and -print some statistics about each pass when it finishes. +When used on the command line prior to @option{--help=}, @option{-Q} +acts as a modifier to the help output. @xref{Overall Options}, +for details about @option{--help=}. + +Otherwise, this option makes the compiler print out each function name +as it is compiled, and print some statistics about each pass when it +finishes. @opindex ftime-report @item -ftime-report |