-fno-nonansi-builtins -fnothrow-opt -fno-operator-names @gol
-fno-optional-diags -fpermissive @gol
-fno-pretty-templates @gol
--frepo -fno-rtti -fsized-deallocation @gol
+-fno-rtti -fsized-deallocation @gol
-ftemplate-backtrace-limit=@var{n} @gol
-ftemplate-depth=@var{n} @gol
-fno-threadsafe-statics -fuse-cxa-atexit @gol
-falign-loops[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
-fassociative-math -fauto-profile -fauto-profile[=@var{path}] @gol
-fauto-inc-dec -fbranch-probabilities @gol
--fbranch-target-load-optimize -fbranch-target-load-optimize2 @gol
--fbtr-bb-exclusive -fcaller-saves @gol
+-fcaller-saves @gol
-fcombine-stack-adjustments -fconserve-stack @gol
-fcompare-elim -fcprop-registers -fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
-march=@var{name} -mcpu=@var{name} -mtune=@var{name} @gol
-moverride=@var{string} -mverbose-cost-dump @gol
-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{sysreg} @gol
--mstack-protector-guard-offset=@var{offset} -mtrack-speculation }
+-mstack-protector-guard-offset=@var{offset} -mtrack-speculation @gol
+-moutline-atomics }
@emph{Adapteva Epiphany Options}
@gccoptlist{-mhalf-reg-file -mprefer-short-insn-regs @gol
-mrestrict-it @gol
-mverbose-cost-dump @gol
-mpure-code @gol
--mcmse}
+-mcmse @gol
+-mfdpic}
@emph{AVR Options}
@gccoptlist{-mmcu=@var{mcu} -mabsdata -maccumulate-args @gol
-msmall-text -mlarge-text @gol
-mmemory-latency=@var{time}}
+@emph{eBPF Options}
+@gccoptlist{-mbig-endian -mlittle-endian -mkernel=@var{version}
+-mframe-limit=@var{bytes}}
+
@emph{FR30 Options}
@gccoptlist{-msmall-model -mno-lsim}
evaluation might take too long.
The default is 33554432 (1<<25).
-@item -fdeduce-init-list
-@opindex fdeduce-init-list
-Enable deduction of a template type parameter as
-@code{std::initializer_list} from a brace-enclosed initializer list, i.e.@:
-
-@smallexample
-template <class T> auto forward(T t) -> decltype (realfn (t))
-@{
- return realfn (t);
-@}
-
-void f()
-@{
- forward(@{1,2@}); // call forward<std::initializer_list<int>>
-@}
-@end smallexample
-
-This deduction was implemented as a possible extension to the
-originally proposed semantics for the C++11 standard, but was not part
-of the final standard, so it is disabled by default. This option is
-deprecated, and may be removed in a future version of G++.
-
@item -fno-elide-constructors
@opindex fno-elide-constructors
@opindex felide-constructors
behaviors make it harder to understand the error message rather than
easier, you can use @option{-fno-pretty-templates} to disable them.
-@item -frepo
-@opindex frepo
-Enable automatic template instantiation at link time. This option also
-implies @option{-fno-implicit-templates}. @xref{Template
-Instantiation}, for more information.
-
@item -fno-rtti
@opindex fno-rtti
@opindex frtti
@item -Wuninitialized
@opindex Wuninitialized
@opindex Wno-uninitialized
-Warn if an automatic variable is used without first being initialized
-or if a variable may be clobbered by a @code{setjmp} call. In C++,
-warn if a non-static reference or non-static @code{const} member
-appears in a class without constructors.
+Warn if an automatic variable is used without first being initialized.
+In C++, warn if a non-static reference or non-static @code{const}
+member appears in a class without constructors.
If you want to warn about code that uses the uninitialized value of the
variable in its own initializer, use the @option{-Winit-self} option.
-These warnings occur for individual uninitialized or clobbered
-elements of structure, union or array variables as well as for
-variables that are uninitialized or clobbered as a whole. They do
-not occur for variables or elements declared @code{volatile}. Because
-these warnings depend on optimization, the exact variables or elements
-for which there are warnings depends on the precise optimization
-options and version of GCC used.
+These warnings occur for individual uninitialized elements of
+structure, union or array variables as well as for variables that are
+uninitialized as a whole. They do not occur for variables or elements
+declared @code{volatile}. Because these warnings depend on
+optimization, the exact variables or elements for which there are
+warnings depend on the precise optimization options and version of GCC
+used.
Note that there may be no warning about a variable that is used only
to compute a value that itself is never used, because such
Objective-C method.
@item -Wshadow=global
-@opindex Wshadow=local
+@opindex Wshadow=global
The default for @option{-Wshadow}. Warns for any (global) shadowing.
+This warning is enabled by @option{-Wshadow=global}.
@item -Wshadow=local
@opindex Wshadow=local
Warn when a local variable shadows another local variable or parameter.
-This warning is enabled by @option{-Wshadow=global}.
+This warning is enabled by @option{-Wshadow=local}.
@item -Wshadow=compatible-local
@opindex Wshadow=compatible-local
warning. So not warning (about shadowing) in this case will not lead to
undetected bugs. Use of this flag instead of @option{-Wshadow=local} can
possibly reduce the number of warnings triggered by intentional shadowing.
+Note that this does also mean that shadowing @code{const char *i} by
+@code{char *i} will not emit a warning.
-This warning is enabled by @option{-Wshadow=local}.
+This warning is enabled by @option{-Wshadow=compatible-local}.
@item -Wlarger-than=@var{byte-size}
@opindex Wlarger-than=
-ffinite-loops @gol
-fgcse -fgcse-lm @gol
-fhoist-adjacent-loads @gol
+-finline-functions @gol
-finline-small-functions @gol
-findirect-inlining @gol
-fipa-bit-cp -fipa-cp -fipa-icf @gol
@c Please keep the following list alphabetized!
@gccoptlist{-fgcse-after-reload @gol
--finline-functions @gol
-fipa-cp-clone
-floop-interchange @gol
-floop-unroll-and-jam @gol
declared @code{static}, then the function is normally not output as
assembler code in its own right.
-Enabled at levels @option{-O3}, @option{-Os}. Also enabled
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}. Also enabled
by @option{-fprofile-use} and @option{-fauto-profile}.
@item -finline-functions-called-once
precedence; and for example @option{-ffp-contract=off} takes precedence
over @option{-ffp-contract=fast}. You can override them at link time.
+To enable debug info generation you need to supply @option{-g} at
+compile-time. If any of the input files at link time were built
+with debug info generation enabled the link will enable debug info
+generation as well. Any elaborate debug info settings
+like the dwarf level @option{-gdwarf-5} need to be explicitly repeated
+at the linker command line and mixing different settings in different
+translation units is discouraged.
+
If LTO encounters objects with C linkage declared with incompatible
types in separate translation units to be linked together (undefined
behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
double} variants, to generate code that raises the ``inexact''
floating-point exception for noninteger arguments. ISO C99 and C11
allow these functions to raise the ``inexact'' exception, but ISO/IEC
-TS 18661-1:2014, the C bindings to IEEE 754-2008, does not allow these
-functions to do so.
+TS 18661-1:2014, the C bindings to IEEE 754-2008, as integrated into
+ISO C2X, does not allow these functions to do so.
The default is @option{-ffp-int-builtin-inexact}, allowing the
-exception to be raised. This option does nothing unless
-@option{-ftrapping-math} is in effect.
+exception to be raised, unless C2X or a later C standard is selected.
+This option does nothing unless @option{-ftrapping-math} is in effect.
Even if @option{-fno-fp-int-builtin-inexact} is used, if the functions
generate a call to a library function then the ``inexact'' exception
link time. An example of such an optimization is relaxing calls to short call
instructions.
-@item -fbranch-target-load-optimize
-@opindex fbranch-target-load-optimize
-Perform branch target register load optimization before prologue / epilogue
-threading.
-The use of target registers can typically be exposed only during reload,
-thus hoisting loads out of loops and doing inter-block scheduling needs
-a separate optimization pass.
-
-@item -fbranch-target-load-optimize2
-@opindex fbranch-target-load-optimize2
-Perform branch target register load optimization after prologue / epilogue
-threading.
-
-@item -fbtr-bb-exclusive
-@opindex fbtr-bb-exclusive
-When performing branch target register load optimization, don't reuse
-branch target registers within any basic block.
-
@item -fstdarg-opt
@opindex fstdarg-opt
Optimize the prologue of variadic argument functions with respect to usage of
compilation time.
@item max-inline-insns-single
-Several parameters control the tree inliner used in GCC@.
-This number sets the maximum number of instructions (counted in GCC's
-internal representation) in a single function that the tree inliner
-considers for inlining. This only affects functions declared
-inline and methods implemented in a class declaration (C++).
+@item max-inline-insns-single-O2
+Several parameters control the tree inliner used in GCC@. This number sets the
+maximum number of instructions (counted in GCC's internal representation) in a
+single function that the tree inliner considers for inlining. This only
+affects functions declared inline and methods implemented in a class
+declaration (C++).
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-single} is
+applied. In other cases @option{max-inline-insns-single-O2} is applied.
+
@item max-inline-insns-auto
+@item max-inline-insns-auto-O2
When you use @option{-finline-functions} (included in @option{-O3}),
a lot of functions that would otherwise not be considered for inlining
by the compiler are investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-auto} is
+applied. In other cases @option{max-inline-insns-auto-O2} is applied.
+
@item max-inline-insns-small
This is bound applied to calls which are considered relevant with
@option{-finline-small-functions}.
Extra time accounted by inliner for function overhead such as time needed to
execute function prologue and epilogue
+@item inline-heuristics-hint-percent
+@item inline-heuristics-hint-percent-O2
+The scale (in percents) applied to @option{inline-insns-single},
+@option{inline-insns-single-O2}, @option{inline-insns-auto},
+@option{inline-insns-auto-O2} when inline heuristics hints that inlining is
+very profitable (will enable later optimizations).
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter
+@option{inline-heuristics-hint-percent} is applied. In other cases
+@option{inline-heuristics-hint-percent-O2} is applied.
+
@item uninlined-thunk-insns
@item uninlined-thunk-time
Same as @option{--param uninlined-function-insns} and
@option{--param uninlined-function-time} but applied to function thunks
@item inline-min-speedup
+@item inline-min-speedup-O2
When estimated performance improvement of caller + callee runtime exceeds this
threshold (in percent), the function can be inlined regardless of the limit on
@option{--param max-inline-insns-single} and @option{--param
max-inline-insns-auto}.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{inline-min-speedup} is
+applied. In other cases @option{inline-min-speedup-O2} is applied.
+
@item large-function-insns
The limit specifying really large functions. For functions larger than this
limit after inlining, inlining is constrained by
expressions whose probability exceeds the given threshold (in percents).
@item early-inlining-insns
+@item early-inlining-insns-O2
Specify growth that the early inliner can make. In effect it increases
the amount of inlining for code having a large abstraction penalty.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{early-inlining-insns} is
+applied. In other cases @option{early-inlining-insns-O2} is applied.
+
@item max-early-inliner-iterations
Limit of iterations of the early inliner. This basically bounds
the number of nested indirect calls the early inliner can resolve.
@option{ipa-sra-ptr-growth-factor} times the size of the original
pointer parameter.
+@item ipa-sra-max-replacements
+Maximum pieces of an aggregate that IPA-SRA tracks. As a
+consequence, it is also the maximum number of replacements of a formal
+parameter.
+
@item sra-max-scalarization-size-Ospeed
@itemx sra-max-scalarization-size-Osize
The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to
consider all memory clobbered after examining
@option{ipa-max-aa-steps} statements modifying memory.
+@item ipa-max-switch-predicate-bounds
+Maximal number of boundary endpoints of case ranges of switch statement.
+For switch exceeding this limit, IPA-CP will not construct cloning cost
+predicate, which is used to estimate cloning benefit, for default case
+of the switch statement.
+
@item lto-partitions
Specify desired number of partitions produced during WHOPR compilation.
The number of partitions should exceed the number of CPUs used for compilation.
* C-SKY Options::
* Darwin Options::
* DEC Alpha Options::
+* eBPF Options::
* FR30 Options::
* FT32 Options::
* FRV Options::
@code{__builtin_speculation_safe_copy} to permit a more efficient code
sequence to be generated.
+@item -moutline-atomics
+@itemx -mno-outline-atomics
+Enable or disable calls to out-of-line helpers to implement atomic operations.
+These helpers will, at runtime, determine if the LSE instructions from
+ARMv8.1-A can be used; if not, they will use the load/store-exclusive
+instructions that are present in the base ARMv8.0 ISA.
+
+This option is only applicable when compiling for the base ARMv8.0
+instruction set. If using a later revision, e.g. @option{-march=armv8.1-a}
+or @option{-march=armv8-a+lse}, the ARMv8.1-Atomics instructions will be
+used directly. The same applies when using @option{-mcpu=} when the
+selected cpu supports the @samp{lse} feature.
+
@item -march=@var{name}
@opindex march
Specify the name of the target architecture and, optionally, one or
Generate secure code as per the "ARMv8-M Security Extensions: Requirements on
Development Tools Engineering Specification", which can be found on
@url{http://infocenter.arm.com/help/topic/com.arm.doc.ecm0359818/ECM0359818_armv8m_security_extensions_reqs_on_dev_tools_1_0.pdf}.
+
+@item -mfdpic
+@itemx -mno-fdpic
+@opindex mfdpic
+@opindex mno-fdpic
+Select the FDPIC ABI, which uses 64-bit function descriptors to
+represent pointers to functions. When the compiler is configured for
+@code{arm-*-uclinuxfdpiceabi} targets, this option is on by default
+and implies @option{-fPIE} if none of the PIC/PIE-related options is
+provided. On other targets, it only enables the FDPIC-specific code
+generation features, and the user should explicitly provide the
+PIC/PIE-related options as needed.
+
+Note that static linking is not supported because it would still
+involve the dynamic linker when the program self-relocates. If such
+behavior is acceptable, use -static and -Wl,-dynamic-linker options.
+
+The opposite @option{-mno-fdpic} option is useful (and required) to
+build the Linux kernel using the same (@code{arm-*-uclinuxfdpiceabi})
+toolchain as the one used to build the userland programs.
+
@end table
@node AVR Options
@end table
@end table
+@node eBPF Options
+@subsection eBPF Options
+@cindex eBPF Options
+
+@table @gcctabopt
+@item -mframe-limit=@var{bytes}
+This specifies the hard limit for frame sizes, in bytes. Currently,
+the value that can be specified should be less than or equal to
+@samp{32767}. Defaults to whatever limit is imposed by the version of
+the Linux kernel targeted.
+
+@item -mkernel=@var{version}
+@opindex mkernel
+This specifies the minimum version of the kernel that will run the
+compiled program. GCC uses this version to determine which
+instructions to use, what kernel helpers to allow, etc. Currently,
+@var{version} can be one of @samp{4.0}, @samp{4.1}, @samp{4.2},
+@samp{4.3}, @samp{4.4}, @samp{4.5}, @samp{4.6}, @samp{4.7},
+@samp{4.8}, @samp{4.9}, @samp{4.10}, @samp{4.11}, @samp{4.12},
+@samp{4.13}, @samp{4.14}, @samp{4.15}, @samp{4.16}, @samp{4.17},
+@samp{4.18}, @samp{4.19}, @samp{4.20}, @samp{5.0}, @samp{5.1},
+@samp{5.2}, @samp{latest} and @samp{native}.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target. This is the default.
+@end table
+
@node FR30 Options
@subsection FR30 Options
@cindex FR30 Options
projects / gcc.git / blobdiff