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[Backport: ARM Documentation] Clarify -mcpu, -mtune, -march 

gcc/

	Backport from mainline.
	2014-02-05  James Greenhalgh  <james.greenhalgh@arm.com>

	PR target/59718
	* doc/invoke.texi (-march): Clarify documentation for ARM.
	(-mtune): Likewise.
	(-mcpu): Likewise.

From-SVN: r207506
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James Greenhalgh 2014-02-05 14:55:18 +00:00 committed by James Greenhalgh
parent 35c726d2a6
commit 5e12387459
2 changed files with 53 additions and 39 deletions
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gcc/ChangeLog
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@ -1,3 +1,13 @@
2014-02-05 James Greenhalgh <james.greenhalgh@arm.com>
Backport from mainline.
2014-02-05 James Greenhalgh <james.greenhalgh@arm.com>
PR target/59718
* doc/invoke.texi (-march): Clarify documentation for ARM.
(-mtune): Likewise.
(-mcpu): Likewise.
2014-02-04 Uros Bizjak <ubizjak@gmail.com>
Backport from mainline

82
gcc/doc/invoke.texi
View File

@ -10648,11 +10648,31 @@ option should only be used if you require compatibility with code for
big-endian ARM processors generated by versions of the compiler prior to
2.8. This option is now deprecated.
@item -mcpu=@var{name}
@opindex mcpu
This specifies the name of the target ARM processor. GCC uses this name
to determine what kind of instructions it can emit when generating
assembly code. Permissible names are: @samp{arm2}, @samp{arm250},
@item -march=@var{name}
@opindex march
This specifies the name of the target ARM architecture. GCC uses this
name to determine what kind of instructions it can emit when generating
assembly code. This option can be used in conjunction with or instead
of the @option{-mcpu=} option. Permissible names are: @samp{armv2},
@samp{armv2a}, @samp{armv3}, @samp{armv3m}, @samp{armv4}, @samp{armv4t},
@samp{armv5}, @samp{armv5t}, @samp{armv5e}, @samp{armv5te},
@samp{armv6}, @samp{armv6j},
@samp{armv6t2}, @samp{armv6z}, @samp{armv6zk}, @samp{armv6-m},
@samp{armv7}, @samp{armv7-a}, @samp{armv7-r}, @samp{armv7-m},
@samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
@option{-march=native} causes the compiler to auto-detect the architecture
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
@item -mtune=@var{name}
@opindex mtune
This option specifies the name of the target ARM processor for
which GCC should tune the performance of the code.
For some ARM implementations better performance can be obtained by using
this option.
Permissible names are: @samp{arm2}, @samp{arm250},
@samp{arm3}, @samp{arm6}, @samp{arm60}, @samp{arm600}, @samp{arm610},
@samp{arm620}, @samp{arm7}, @samp{arm7m}, @samp{arm7d}, @samp{arm7dm},
@samp{arm7di}, @samp{arm7dmi}, @samp{arm70}, @samp{arm700},
@ -10678,27 +10698,6 @@ assembly code. Permissible names are: @samp{arm2}, @samp{arm250},
@samp{fa526}, @samp{fa626},
@samp{fa606te}, @samp{fa626te}, @samp{fmp626}, @samp{fa726te}.
@option{-mcpu=generic-@var{arch}} is also permissible, and is
equivalent to @option{-march=@var{arch} -mtune=generic-@var{arch}}.
See @option{-mtune} for more information.
@option{-mcpu=native} causes the compiler to auto-detect the CPU
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
@item -mtune=@var{name}
@opindex mtune
This option is very similar to the @option{-mcpu=} option, except that
instead of specifying the actual target processor type, and hence
restricting which instructions can be used, it specifies that GCC should
tune the performance of the code as if the target were of the type
specified in this option, but still choosing the instructions that it
will generate based on the CPU specified by a @option{-mcpu=} option.
For some ARM implementations better performance can be obtained by using
this option.
@option{-mtune=generic-@var{arch}} specifies that GCC should tune the
performance for a blend of processors within architecture @var{arch}.
The aim is to generate code that run well on the current most popular
@ -10711,20 +10710,25 @@ of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.
@item -march=@var{name}
@opindex march
This specifies the name of the target ARM architecture. GCC uses this
name to determine what kind of instructions it can emit when generating
assembly code. This option can be used in conjunction with or instead
of the @option{-mcpu=} option. Permissible names are: @samp{armv2},
@samp{armv2a}, @samp{armv3}, @samp{armv3m}, @samp{armv4}, @samp{armv4t},
@samp{armv5}, @samp{armv5t}, @samp{armv5e}, @samp{armv5te},
@samp{armv6}, @samp{armv6j},
@samp{armv6t2}, @samp{armv6z}, @samp{armv6zk}, @samp{armv6-m},
@samp{armv7}, @samp{armv7-a}, @samp{armv7-r}, @samp{armv7-m},
@samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
@item -mcpu=@var{name}
@opindex mcpu
This specifies the name of the target ARM processor. GCC uses this name
to derive the name of the target ARM architecture (as if specified
by @option{-march}) and the ARM processor type for which to tune for
performance (as if specified by @option{-mtune}). Where this option
is used in conjunction with @option{-march} or @option{-mtune},
those options take precedence over the appropriate part of this option.
@option{-march=native} causes the compiler to auto-detect the architecture
Permissible names for this option are the same as those for
@option{-mtune}.
ssembly code.
@option{-mcpu=generic-@var{arch}} is also permissible, and is
equivalent to @option{-march=@var{arch} -mtune=generic-@var{arch}}.
See @option{-mtune} for more information.
@option{-mcpu=native} causes the compiler to auto-detect the CPU
of the build computer. At present, this feature is only supported on
Linux, and not all architectures are recognized. If the auto-detect is
unsuccessful the option has no effect.