@emph{S/390 and zSeries Options} (@ref{S/390 and zSeries Options})
@gccoptlist{-mtune=@var{cpu-type} -march=@var{cpu-type}
--mhard-float -msoft-float -mhard-dfp -mno-hard-dfp
+-mhard-float -msoft-float -mhard-dfp
-mlong-double-64 -mlong-double-128
--mbackchain -mno-backchain -mpacked-stack -mno-packed-stack
--msmall-exec -mno-small-exec -mmvcle -mno-mvcle
--m64 -m31 -mdebug -mno-debug -mesa -mzarch
+-mbackchain -mpacked-stack
+-msmall-exec -mmvcle
+-m64 -m31 -mdebug -mesa -mzarch
-mhtm -mvx -mzvector
--mtpf-trace -mno-tpf-trace -mtpf-trace-skip -mno-tpf-trace-skip
+-mtpf-trace -mtpf-trace-skip -mmain
-mfused-madd -mno-fused-madd
--mwarn-framesize -mwarn-dynamicstack -mstack-size -mstack-guard
--mhotpatch=@var{halfwords},@var{halfwords}}
+-mwarn-framesize=@var{framesize} -mwarn-dynamicstack
+-mstack-size=@var{stack-size} -mno-stack-size
+-mstack-guard=@var{stack-guard} -mno-stack-guard
+-mstack-protector-guard=@var{guard}
+-mstack-protector-guard-record
+-mhotpatch=@var{pre-halfwords},@var{post-halfwords}
+-mno-pic-data-is-text-relative
+-mindirect-branch=@var{choice}
+-mindirect-branch-jump=@var{choice} -mindirect-branch-call=@var{choice}
+-mfunction-return=@var{choice}
+-mfunction-return-mem=@var{choice} -mfunction-return-reg=@var{choice}
+-mindirect-branch-table
+-mfentry -mrecord-mcount -mnop-mcount
+-mpreserve-args -munaliged-symbols}
@emph{SH Options} (@ref{SH Options})
@gccoptlist{-m1 -m2 -m2e
z13 machine generation.
This option changes the ABI for some vector type values with regard to
alignment and calling conventions. In case vector type values are
-being used in an ABI-relevant context a GAS @samp{.gnu_attribute}
-command will be added to mark the resulting binary with the ABI used.
+being used in an ABI-relevant context, a GAS @samp{.gnu_attribute}
+command is added to mark the resulting binary with the ABI used.
@option{-mvx} is enabled by default when using @option{-march=z13}.
@opindex mzvector
facility introduced with the IBM z13 machine generation.
This option adds support for @samp{vector} to be used as a keyword to
define vector type variables and arguments. @samp{vector} is only
-available when GNU extensions are enabled. It will not be expanded
+available when GNU extensions are enabled. It is not expanded
when requesting strict standard compliance e.g.@: with @option{-std=c99}.
-In addition to the GCC low-level builtins @option{-mzvector} enables
+In addition to the GCC low-level builtins, @option{-mzvector} enables
a set of builtins added for compatibility with AltiVec-style
implementations like Power and Cell. In order to make use of these
-builtins the header file @file{vecintrin.h} needs to be included.
+builtins, you must include the header file @file{vecintrin.h}.
@option{-mzvector} is disabled by default.
@opindex mmvcle
entries for the TPF OS. This option is off by default, even when
compiling for the TPF OS and specifying @option{-mtpf-trace}.
+@opindex mmain
+@opindex mno-main
+@item -mmain
+For TPF OS target, use this option when linking to add the startup code
+and other linker options to produce a main object.
+
@opindex mfused-madd
@opindex mno-fused-madd
@item -mfused-madd
@opindex mwarn-framesize
@item -mwarn-framesize=@var{framesize}
-Emit a warning if the current function exceeds the given frame size. Because
-this is a compile-time check it doesn't need to be a real problem when the program
-runs. It is intended to identify functions that most probably cause
-a stack overflow. It is useful to be used in an environment with limited stack
-size e.g.@: the linux kernel.
+Emit a warning if the current function exceeds the given frame size.
+Because this is a compile-time check it doesn't need to be a real
+problem when the program runs. It is intended to identify functions
+hat most probably cause a stack overflow. It is useful for
+environments with limited stack size e.g.@: the Linux kernel.
+
+A value of zero disables this warning; that is the default.
@opindex mwarn-dynamicstack
+@opindex mno-warn-dynamicstack
@item -mwarn-dynamicstack
+@itemx -mno-warn-dynamicstack
Emit a warning if the function calls @code{alloca} or uses dynamically-sized
arrays. This is generally a bad idea with a limited stack size.
@opindex mstack-guard
@opindex mstack-size
+@opindex mno-stack-guard
+@opindex mno-stack-size
@item -mstack-guard=@var{stack-guard}
@itemx -mstack-size=@var{stack-size}
-If these options are provided the S/390 back end emits additional instructions in
-the function prologue that trigger a trap if the stack size is @var{stack-guard}
-bytes above the @var{stack-size} (remember that the stack on S/390 grows downward).
+@itemx -mno-stack-guard
+@itemx -mno-stack-size
+If these options are enabled, the S/390 back end emits additional
+instructions in the function prologue that trigger a trap if the stack
+size is @var{stack-guard} bytes above the @var{stack-size} (remember that
+the stack on S/390 grows downward).
If the @var{stack-guard} option is omitted the smallest power of 2 larger than
the frame size of the compiled function is chosen.
-These options are intended to be used to help debugging stack overflow problems.
-The additionally emitted code causes only little overhead and hence can also be
-used in production-like systems without greater performance degradation. The given
-values have to be exact powers of 2 and @var{stack-size} has to be greater than
-@var{stack-guard} without exceeding 64k.
-In order to be efficient the extra code makes the assumption that the stack starts
-at an address aligned to the value given by @var{stack-size}.
-The @var{stack-guard} option can only be used in conjunction with @var{stack-size}.
+
+These options are intended to be used to help debugging stack overflow
+problems. The additionally emitted code causes only little overhead and
+hence can also be used in production-like systems without greater
+performance degradation.
+
+The given values have to be exact powers of 2
+and @var{stack-size} has to be greater than @var{stack-guard} without
+exceeding 64k.
+In order to be efficient the extra code makes the assumption that the
+stack starts at an address aligned to the value given by @var{stack-size}.
+
+The @option{-mstack-guard=} option can only be used in conjunction with
+@option{-mstack-size=}. You can override these options on the command line
+with @option{-mno-stack-guard} and @option{-mno-stack-size}, respectively.
@opindex mhotpatch
@item -mhotpatch=@var{pre-halfwords},@var{post-halfwords}
If the hotpatch option is enabled, a ``hot-patching'' function
prologue is generated for all functions in the compilation unit.
-The funtion label is prepended with the given number of two-byte
+The function label is prepended with the given number of two-byte
NOP instructions (@var{pre-halfwords}, maximum 1000000). After
the label, 2 * @var{post-halfwords} bytes are appended, using the
-largest NOP like instructions the architecture allows (maximum
+largest NOP-like instructions the architecture allows (maximum
1000000).
If both arguments are zero, hotpatching is disabled.
This option can be overridden for individual functions with the
@code{hotpatch} attribute.
+@opindex mpic-data-is-text-relative
+@opindex mno-pic-data-is-text-relative
+@item -mpic-data-is-text-relative
+@itemx -mno-pic-data-is-text-relative
+When compiling for S/390 with @option{-fpic} or @option{-fPIC}, normally
+GCC emits code using relative addressing between code and data. However,
+for hotpatching it might be required to introduce new @code{.text} parts
+while using the existing @code{.data} and @code{.bss} sections.
+In this case, use @option{-mno-pic-data-is-text-relative} to force
+addressing through the GOT instead.
+
@opindex mstack-protector-guard
@opindex mstack-protector-guard-record
+@opindex mno-stack-protector-guard-record
@item -mstack-protector-guard=@var{guard}
@itemx -mstack-protector-guard-record
+
Generate stack protection code using canary at @var{guard}. Supported
-locations are @var{global} for a global canary or @var{tls} for a per-thread
+locations are @samp{global} for a global canary or @samp{tls} for a per-thread
canary in the TLS block (the default).
Option @option{-mstack-protector-guard-record} results in the generation of
which load the address of the global guard. Thus, this option has only an
effect in conjunction with @option{-mstack-protector-guard=global}. The
intended use is for the Linux kernel.
+
+@opindex mindirect-branch
+@opindex mindirect-branch-jump
+@opindex mindirect-branch-call
+@opindex mfunction-return
+@opindex mfunction-return-mem
+@opindex mfunction-return-reg
+@item -mindirect-branch=@var{choice}
+@itemx -mindirect-branch-jump=@var{choice}
+@itemx -mindirect-branch-call=@var{choice}
+@itemx -mfunction-return=@var{choice}
+@itemx -mfunction-return-mem=@var{choice}
+@itemx -mfunction-return-reg=@var{choice}
+This group of options addresses security vulnerabilities related to
+speculative execution and indirect branch prediction by enabling replacement
+of indirect branches and function returns with direct branches to a thunk.
+
+Specifying a @var{choice} of @samp{keep} causes generation of the
+default code. @samp{thunk} triggers generation of out-of-line thunks
+and replaces the formerly indirect branch with a direct branch to the
+thunk. @samp{thunk-extern} does the branch replacement like @samp{thunk}
+but does not emit the thunks. @samp{thunk-inline} is only available with
+@option{-mindirect-branch-jump}; it should be used in preference
+to @samp{thunk} in user-space applications to support correct stack
+unwinding and exception handling.
+
+@option{-mindirect-branch} sets the value of @option{-mindirect-branch-jump}
+and @option{-mindirect-branch-call}.
+@option{-mfunction-return} sets the value of @option{-mfunction-return-reg}
+and @option{-mfunction-return-mem.}
+
+All of these options can also be set on a per-function basis using
+function attributes.
+
+@opindex mindirect-branch-table
+@opindex mno-indirect-branch-table
+@item -mindirect-branch-table
+@itemx -mno-indirect-branch-table
+
+This option is useful in conjunction with the
+@option{-mindirect-branch} and @option{-mfunction-return} options.
+When enabled, it causes generation of tables pointing to the branch
+locations which have been patched by those options. The tables are
+emitted in sections named @code{.s390_indirect_jump},
+@code{.s390_indirect_call}, @code{.s390_return_reg}, and
+@code{.s390_return_mem}. Each section consists of an array of 32-bit
+elements; each entry holds the offset from the entry to the patched
+location.
+
+@opindex mfentry
+@opindex mno-fentry
+@item -mfentry
+@itemx -mno-fentry
+When used in conjunction with the @option{-pg} option, emit profiling code
+using the @code{__fentry__} hook provided by GLIBC 2.29 or later.
+This is only available for 64-bit code. If this option is not enabled,
+profiling uses the less efficient @code{_mcount} hook instead.
+
+@opindex mrecord-mcount
+@opindex mno-record-mcount
+@item -mrecord-mcount
+@itemx -mno-record-mcount
+When enabled, generate a @code{__mcount_loc} section with the locations
+of all generated profiling calls to @code{_mcount} or @code{__fentry__}.
+
+@opindex mnop-mcount
+@opindex mno-nop-mcount
+@item mnop-mcount
+@itemx mno-nop-mcount
+Instead of generating calls to @code{_mcount} or @code{__fentry__}
+with @option{-pg}, insert a sequence no-op instructions of the same length
+at the locations where the calls would have been inserted. This can be used
+in conjunction with the @option{-mrecord-mcount} option to patch the call
+sequences into the object file without recompiling it.
+
+@opindex mpreserve-args
+@opindex mno-preserve-args
+@item -mpreserve-args
+@itemx -mno-preserve-args
+When enabled, save all argument registers to the stack, and generate
+corresponding CFI information. This is useful for applications that
+want to implement their own stack unwinding and need access to function
+arguments.
+
+@opindex munaligned-symbols
+@opindex mno-unaligned-symbols
+@item -munaligned-symbols
+@itemx -mno-unaligned-symbols
+Assume that external symbols with a natural alignment of 1 are potentially
+unaligned. By default, all symbols without explicit alignment are assumed
+to be aligned on a 2-byte boundary as mandated by the IBM Z ABI.
@end table
@node SH Options
projects / thirdparty / gcc.git / commitdiff
