| Message ID | 20180207224826.GA15076@ibm-tiger.the-meissners.org |
|---|---|
| State | New |
| Headers | show |
| Series | , Document the PowerPC --with-long-double-format={ibm,ieee} configuration options | expand |
On Wed, Feb 07, 2018 at 05:48:26PM -0500, Michael Meissner wrote: > This patch udpates the GCC installation documentation to document the > configuration options to set the long double type on the PowerPC: I verified > that the documentation builds. Can I install this on to the trunk? Yes please, thanks! A few minor issues: > 2018-02-07 Michael Meissner <meissner@linux.vnet.ibm.com> > > * doc/install.texi (Configuration): Document the > --with-long-double-format={ibm,eee} PowerPC configuration > options. Typo ("ieee"). > +@item --with-long-double-format=ibm > +@itemx --with-long-double-format-ieee Typo ("=ieee"). > +systems. If you are building multilibs, you will need to configure > +the compiler using the @option{--with-system-zlib} option. Why is that? Is that a bug? On BE we build multilibs all the time, and we do not need that flag. Segher
On Wed, Feb 07, 2018 at 05:26:49PM -0600, Segher Boessenkool wrote: > On Wed, Feb 07, 2018 at 05:48:26PM -0500, Michael Meissner wrote: > > This patch udpates the GCC installation documentation to document the > > configuration options to set the long double type on the PowerPC: I verified > > that the documentation builds. Can I install this on to the trunk? > > Yes please, thanks! A few minor issues: > > > 2018-02-07 Michael Meissner <meissner@linux.vnet.ibm.com> > > > > * doc/install.texi (Configuration): Document the > > --with-long-double-format={ibm,eee} PowerPC configuration > > options. > > Typo ("ieee"). > > > +@item --with-long-double-format=ibm > > +@itemx --with-long-double-format-ieee > > Typo ("=ieee"). > > > +systems. If you are building multilibs, you will need to configure > > +the compiler using the @option{--with-system-zlib} option. Thanks. > Why is that? Is that a bug? On BE we build multilibs all the time, > and we do not need that flag. No idea. I imagine we will probably see the issue if/when we add IEEE multilibs to big endian.
Index: gcc/doc/install.texi =================================================================== --- gcc/doc/install.texi (revision 257455) +++ gcc/doc/install.texi (working copy) @@ -1877,6 +1877,35 @@ When neither of these configure options 128-bit @code{long double} when built against GNU C Library 2.4 and later, 64-bit @code{long double} otherwise. +@item --with-long-double-format=ibm +@itemx --with-long-double-format-ieee +Specify whether @code{long double} uses the IBM extended double format +or the IEEE 128-bit floating point format on PowerPC Linux systems. +This configuration switch will only work on little endian PowerPC +Linux systems and on big endian 64-bit systems where the default cpu +is at least power7 (i.e. @option{--with-cpu=power7}, +@option{--with-cpu=power8}, or @option{--with-cpu=power9} is used). + +If you use the @option{--with-long-double-64} configuration option, +the @option{--with-long-double-format=ibm} and +@option{--with-long-double-format=ieee} options are ignored. + +The default @code{long double} format is to use IBM extended double. +Until all of the libraries are converted to use IEEE 128-bit floating +point, it is not recommended to use +@option{--with-long-double-format=ieee}. + +On little endian PowerPC Linux systems, if you explicitly set the +@code{long double} type, it will build multilibs to allow you to +select either @code{long double} format, unless you disable multilibs +with the @code{--disable-multilib} option. At present, +@code{long double} multilibs are not built on big endian PowerPC Linux +systems. If you are building multilibs, you will need to configure +the compiler using the @option{--with-system-zlib} option. + +If you do not set the @code{long double} type explicitly, no multilibs +will be generated. + @item --enable-fdpic On SH Linux systems, generate ELF FDPIC code.
This patch udpates the GCC installation documentation to document the configuration options to set the long double type on the PowerPC: I verified that the documentation builds. Can I install this on to the trunk? 2018-02-07 Michael Meissner <meissner@linux.vnet.ibm.com> * doc/install.texi (Configuration): Document the --with-long-double-format={ibm,eee} PowerPC configuration options.