@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@gccoptlist{-ansi -std=@var{standard} -fgnu89-inline @gol
+-fpermitted-flt-eval-methods=@var{standard} @gol
-aux-info @var{filename} -fallow-parameterless-variadic-functions @gol
--fno-asm -fno-builtin -fno-builtin-@var{function} @gol
+-fno-asm -fno-builtin -fno-builtin-@var{function} -fgimple@gol
-fhosted -ffreestanding -fopenacc -fopenmp -fopenmp-simd @gol
-fms-extensions -fplan9-extensions -fsso-struct=@var{endianness}
-fallow-single-precision -fcond-mismatch -flax-vector-conversions @gol
@gccoptlist{-fsyntax-only -fmax-errors=@var{n} -Wpedantic @gol
-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return @gol
+-Walloc-zero -Walloc-size-larger-than=@var{n}
-Walloca -Walloca-larger-than=@var{n} @gol
-Wno-aggressive-loop-optimizations -Warray-bounds -Warray-bounds=@var{n} @gol
-Wno-attributes -Wbool-compare -Wbool-operation @gol
+-Wno-builtin-declaration-mismatch @gol
-Wno-builtin-macro-redefined -Wc90-c99-compat -Wc99-c11-compat @gol
-Wc++-compat -Wc++11-compat -Wc++14-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment -Wconditionally-supported @gol
-Wsizeof-pointer-memaccess -Wsizeof-array-argument @gol
-Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol
-Wstrict-aliasing=n -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
+-Wstringop-overflow=@var{n} @gol
-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]} @gol
-Wsuggest-final-types @gol -Wsuggest-final-methods -Wsuggest-override @gol
-Wmissing-format-attribute -Wsubobject-linkage @gol
-fno-ira-share-spill-slots @gol
-fisolate-erroneous-paths-dereference -fisolate-erroneous-paths-attribute @gol
-fivopts -fkeep-inline-functions -fkeep-static-functions @gol
--fkeep-static-consts -flive-range-shrinkage @gol
+-fkeep-static-consts -flimit-function-alignment -flive-range-shrinkage @gol
-floop-block -floop-interchange -floop-strip-mine @gol
-floop-unroll-and-jam -floop-nest-optimize @gol
-floop-parallelize-all -flra-remat -flto -flto-compression-level @gol
-fmove-loop-invariants -fno-branch-count-reg @gol
-fno-defer-pop -fno-fp-int-builtin-inexact -fno-function-cse @gol
-fno-guess-branch-probability -fno-inline -fno-math-errno -fno-peephole @gol
--fno-peephole2 -fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
+-fno-peephole2 -fno-printf-return-value -fno-sched-interblock @gol
+-fno-sched-spec -fno-signed-zeros @gol
-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
-fomit-frame-pointer -foptimize-sibling-calls @gol
-fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
--fprefetch-loop-arrays -fprintf-return-value @gol
+-fprefetch-loop-arrays @gol
-fprofile-correction @gol
-fprofile-use -fprofile-use=@var{path} -fprofile-values @gol
-fprofile-reorder-functions @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
-ftree-coalesce-vars -ftree-copy-prop -ftree-dce -ftree-dominator-opts @gol
-ftree-dse -ftree-forwprop -ftree-fre -fcode-hoisting -ftree-loop-if-convert @gol
--ftree-loop-if-convert-stores -ftree-loop-im @gol
+-ftree-loop-im @gol
-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-loop-vectorize @gol
-mcrc -mdsp-packa -mdvbf -mlock -mmac-d16 -mmac-24 -mrtsc -mswape @gol
-mtelephony -mxy -misize -mannotate-align -marclinux -marclinux_prof @gol
-mlong-calls -mmedium-calls -msdata @gol
--mucb-mcount -mvolatile-cache -mtp-regno=@var{regno} @gol
+-mvolatile-cache -mtp-regno=@var{regno} @gol
-malign-call -mauto-modify-reg -mbbit-peephole -mno-brcc @gol
-mcase-vector-pcrel -mcompact-casesi -mno-cond-exec -mearly-cbranchsi @gol
-mexpand-adddi -mindexed-loads -mlra -mlra-priority-none @gol
@gccoptlist{-mapcs-frame -mno-apcs-frame @gol
-mabi=@var{name} @gol
-mapcs-stack-check -mno-apcs-stack-check @gol
--mapcs-float -mno-apcs-float @gol
-mapcs-reentrant -mno-apcs-reentrant @gol
-msched-prolog -mno-sched-prolog @gol
-mlittle-endian -mbig-endian @gol
-mslow-flash-data @gol
-masm-syntax-unified @gol
-mrestrict-it @gol
--mpure-code}
+-mpure-code @gol
+-mcmse}
@emph{AVR Options}
@gccoptlist{-mmcu=@var{mcu} -mabsdata -maccumulate-args @gol
@emph{HPPA Options}
@gccoptlist{-march=@var{architecture-type} @gol
--mdisable-fpregs -mdisable-indexing @gol
+-mcaller-copies -mdisable-fpregs -mdisable-indexing @gol
-mfast-indirect-calls -mgas -mgnu-ld -mhp-ld @gol
-mfixed-range=@var{register-range} @gol
-mjump-in-delay -mlinker-opt -mlong-calls @gol
@item @var{file}.go
Go source code.
-@c FIXME: Descriptions of Java file types.
-@c @var{file}.java
-@c @var{file}.class
-@c @var{file}.zip
-@c @var{file}.jar
-
@item @var{file}.ads
Ada source code file that contains a library unit declaration (a
declaration of a package, subprogram, or generic, or a generic
ada
f77 f77-cpp-input f95 f95-cpp-input
go
-java
@end smallexample
@item -x none
in effect for @code{inline} functions. @xref{Common Predefined
Macros,,,cpp,The C Preprocessor}.
+@item -fpermitted-flt-eval-methods=@var{style}
+@opindex fpermitted-flt-eval-methods
+@opindex fpermitted-flt-eval-methods=c11
+@opindex fpermitted-flt-eval-methods=ts-18661-3
+ISO/IEC TS 18661-3 defines new permissible values for
+@code{FLT_EVAL_METHOD} that indicate that operations and constants with
+a semantic type that is an interchange or extended format should be
+evaluated to the precision and range of that type. These new values are
+a superset of those permitted under C99/C11, which does not specify the
+meaning of other positive values of @code{FLT_EVAL_METHOD}. As such, code
+conforming to C11 may not have been written expecting the possibility of
+the new values.
+
+@option{-fpermitted-flt-eval-methods} specifies whether the compiler
+should allow only the values of @code{FLT_EVAL_METHOD} specified in C99/C11,
+or the extended set of values specified in ISO/IEC TS 18661-3.
+
+@var{style} is either @code{c11} or @code{ts-18661-3} as appropriate.
+
+The default when in a standards compliant mode (@option{-std=c11} or similar)
+is @option{-fpermitted-flt-eval-methods=c11}. The default when in a GNU
+dialect (@option{-std=gnu11} or similar) is
+@option{-fpermitted-flt-eval-methods=ts-18661-3}.
+
@item -aux-info @var{filename}
@opindex aux-info
Output to the given filename prototyped declarations for all functions
#define strcpy(d, s) __builtin_strcpy ((d), (s))
@end smallexample
+@item -fgimple
+@opindex fgimple
+
+Enable parsing of function definitions marked with @code{__GIMPLE}.
+This is an experimental feature that allows unit testing of GIMPLE
+passes.
+
@item -fhosted
@opindex fhosted
@cindex hosted environment
@item -fobjc-exceptions
@opindex fobjc-exceptions
Enable syntactic support for structured exception handling in
-Objective-C, similar to what is offered by C++ and Java. This option
+Objective-C, similar to what is offered by C++. This option
is required to use the Objective-C keywords @code{@@try},
@code{@@throw}, @code{@@catch}, @code{@@finally} and
@code{@@synchronized}. This option is available with both the GNU
false positives.
@end table
+@item -Wstringop-overflow
+@itemx -Wstringop-overflow=@var{type}
+@opindex Wstringop-overflow
+@opindex Wno-stringop-overflow
+Warn for calls to string manipulation functions such as @code{memcpy} and
+@code{strcpy} that are determined to overflow the destination buffer. The
+optional argument is one greater than the type of Object Size Checking to
+perform to determine the size of the destination. @xref{Object Size Checking}.
+The argument is meaningful only for functions that operate on character arrays
+but not for raw memory functions like @code{memcpy} which always make use
+of Object Size type-0. The option also warns for calls that specify a size
+in excess of the largest possible object or at most @code{SIZE_MAX / 2} bytes.
+The option produces the best results with optimization enabled but can detect
+a small subset of simple buffer overflows even without optimization in
+calls to the GCC built-in functions like @code{__builtin_memcpy} that
+correspond to the standard functions. In any case, the option warns about
+just a subset of buffer overflows detected by the corresponding overflow
+checking built-ins. For example, the option will issue a warning for
+the @code{strcpy} call below because it copies at least 5 characters
+(the string @code{"blue"} including the terminating NUL) into the buffer
+of size 4.
+
+@smallexample
+enum Color @{ blue, purple, yellow @};
+const char* f (enum Color clr)
+@{
+ static char buf [4];
+ const char *str;
+ switch (clr)
+ @{
+ case blue: str = "blue"; break;
+ case purple: str = "purple"; break;
+ case yellow: str = "yellow"; break;
+ @}
+
+ return strcpy (buf, str); // warning here
+@}
+@end smallexample
+
+Option @option{-Wstringop-overflow=2} is enabled by default.
+
+@table @gcctabopt
+@item -Wstringop-overflow
+@item -Wstringop-overflow=1
+@opindex Wstringop-overflow
+@opindex Wno-stringop-overflow
+The @option{-Wstringop-overflow=1} option uses type-zero Object Size Checking
+to determine the sizes of destination objects. This is the default setting
+of the option. At this setting the option will not warn for writes past
+the end of subobjects of larger objects accessed by pointers unless the
+size of the largest surrounding object is known. When the destination may
+be one of several objects it is assumed to be the largest one of them. On
+Linux systems, when optimization is enabled at this setting the option warns
+for the same code as when the @code{_FORTIFY_SOURCE} macro is defined to
+a non-zero value.
+
+@item -Wstringop-overflow=2
+The @option{-Wstringop-overflow=2} option uses type-one Object Size Checking
+to determine the sizes of destination objects. At this setting the option
+will warn about overflows when writing to members of the largest complete
+objects whose exact size is known. It will, however, not warn for excessive
+writes to the same members of unknown objects referenced by pointers since
+they may point to arrays containing unknown numbers of elements.
+
+@item -Wstringop-overflow=3
+The @option{-Wstringop-overflow=3} option uses type-two Object Size Checking
+to determine the sizes of destination objects. At this setting the option
+warns about overflowing the smallest object or data member. This is the
+most restrictive setting of the option that may result in warnings for safe
+code.
+
+@item -Wstringop-overflow=4
+The @option{-Wstringop-overflow=4} option uses type-three Object Size Checking
+to determine the sizes of destination objects. At this setting the option
+will warn about overflowing any data members, and when the destination is
+one of several objects it uses the size of the largest of them to decide
+whether to issue a warning. Similarly to @option{-Wstringop-overflow=3} this
+setting of the option may result in warnings for benign code.
+@end table
+
@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{]}
@opindex Wsuggest-attribute=
@opindex Wno-suggest-attribute=
Warn about overriding virtual functions that are not marked with the override
keyword.
+@item -Walloc-zero
+@opindex Wno-alloc-zero
+@opindex Walloc-zero
+Warn about calls to allocation functions decorated with attribute
+@code{alloc_size} that specify zero bytes, including those to the built-in
+forms of the functions @code{aligned_alloc}, @code{alloca}, @code{calloc},
+@code{malloc}, and @code{realloc}. Because the behavior of these functions
+when called with a zero size differs among implementations (and in the case
+of @code{realloc} has been deprecated) relying on it may result in subtle
+portability bugs and should be avoided.
+
+@item -Walloc-size-larger-than=@var{n}
+Warn about calls to functions decorated with attribute @code{alloc_size}
+that attempt to allocate objects larger than the specified number of bytes,
+or where the result of the size computation in an integer type with infinite
+precision would exceed @code{SIZE_MAX / 2}. The option argument @var{n}
+may end in one of the standard suffixes designating a multiple of bytes
+such as @code{kB} and @code{KiB} for kilobyte and kibibyte, respectively,
+@code{MB} and @code{MiB} for magabyte and mebibyte, and so on.
+@xref{Function Attributes}.
+
@item -Walloca
@opindex Wno-alloca
@opindex Walloca
construct, known from C++, was introduced with ISO C99 and is by default
allowed in GCC@. It is not supported by ISO C90. @xref{Mixed Declarations}.
+@item -Wexpansion-to-defined
+@opindex Wexpansion-to-defined
+Warn whenever @samp{defined} is encountered in the expansion of a macro.
+This warning is also enabled by @option{-Wpedantic} and @option{-Wextra}.
+
@item -Wundef
@opindex Wundef
@opindex Wno-undef
etc. This does not stop errors for incorrect use of supported
attributes.
+@item -Wno-builtin-declaration-mismatch
+@opindex Wno-builtin-declaration-mismatch
+@opindex Wbuiltin-declaration-mismatch
+Warn if a built-in function is declared with the wrong signature.
+This warning is enabled by default.
+
@item -Wno-builtin-macro-redefined
@opindex Wno-builtin-macro-redefined
@opindex Wbuiltin-macro-redefined
@opindex fno-keep-inline-dllexport
This is a more fine-grained version of @option{-fkeep-inline-functions},
which applies only to functions that are declared using the @code{dllexport}
-attribute or declspec (@xref{Function Attributes,,Declaring Attributes of
-Functions}.)
+attribute or declspec. @xref{Function Attributes,,Declaring Attributes of
+Functions}.
@item -fkeep-inline-functions
@opindex fkeep-inline-functions
vectorization pass to handle these loops. This is enabled by default
if vectorization is enabled.
-@item -ftree-loop-if-convert-stores
-@opindex ftree-loop-if-convert-stores
-Attempt to also if-convert conditional jumps containing memory writes.
-This transformation can be unsafe for multi-threaded programs as it
-transforms conditional memory writes into unconditional memory writes.
-For example,
-@smallexample
-for (i = 0; i < N; i++)
- if (cond)
- A[i] = expr;
-@end smallexample
-is transformed to
-@smallexample
-for (i = 0; i < N; i++)
- A[i] = cond ? expr : A[i];
-@end smallexample
-potentially producing data races.
-
@item -ftree-loop-distribution
@opindex ftree-loop-distribution
Perform loop distribution. This flag can improve cache performance on
Disabled at level @option{-Os}.
-@item -fprintf-return-value
-@opindex fprintf-return-value
-Substitute constants for known return value of formatted output functions
-such as @code{sprintf}, @code{snprintf}, @code{vsprintf}, and @code{vsnprintf}
-(but not @code{printf} of @code{fprintf}). This transformation allows GCC
-to optimize or even eliminate branches based on the known return value of
-these functions called with arguments that are either constant, or whose
-values are known to be in a range that makes determining the exact return
-value possible. For example, both the branch and the body of the @code{if}
-statement (but not the call to @code{snprint}) can be optimized away when
-@code{i} is a 32-bit or smaller integer because the return value is guaranteed
-to be at most 8.
+@item -fno-printf-return-value
+@opindex fno-printf-return-value
+Do not substitute constants for known return value of formatted output
+functions such as @code{sprintf}, @code{snprintf}, @code{vsprintf}, and
+@code{vsnprintf} (but not @code{printf} of @code{fprintf}). This
+transformation allows GCC to optimize or even eliminate branches based
+on the known return value of these functions called with arguments that
+are either constant, or whose values are known to be in a range that
+makes determining the exact return value possible. For example, when
+@option{-fprintf-return-value} is in effect, both the branch and the
+body of the @code{if} statement (but not the call to @code{snprint})
+can be optimized away when @code{i} is a 32-bit or smaller integer
+because the return value is guaranteed to be at most 8.
@smallexample
char buf[9];
The @option{-fprintf-return-value} option relies on other optimizations
and yields best results with @option{-O2}. It works in tandem with the
@option{-Wformat-length} option. The @option{-fprintf-return-value}
-option is disabled by default.
+option is enabled by default.
@item -fno-peephole
@itemx -fno-peephole2
Enabled at levels @option{-O2}, @option{-O3}.
+@item -flimit-function-alignment
+If this option is enabled, the compiler tries to avoid unnecessarily
+overaligning functions. It attempts to instruct the assembler to align
+by the amount specified by @option{-falign-functions}, but not to
+skip more bytes than the size of the function.
+
@item -falign-labels
@itemx -falign-labels=@var{n}
@opindex falign-labels
@option{-ftree-vectorize}, and @option{ftree-loop-distribute-patterns}.
Before you can use this option, you must first generate profiling information.
-@xref{Optimize Options}, for information about the @option{-fprofile-generate}
-option.
+@xref{Instrumentation Options}, for information about the
+@option{-fprofile-generate} option.
By default, GCC emits an error message if the feedback profiles do not
match the source code. This error can be turned into a warning by using
@item -fexcess-precision=@var{style}
@opindex fexcess-precision
This option allows further control over excess precision on machines
-where floating-point registers have more precision than the IEEE
-@code{float} and @code{double} types and the processor does not
-support operations rounding to those types. By default,
-@option{-fexcess-precision=fast} is in effect; this means that
-operations are carried out in the precision of the registers and that
-it is unpredictable when rounding to the types specified in the source
-code takes place. When compiling C, if
-@option{-fexcess-precision=standard} is specified then excess
-precision follows the rules specified in ISO C99; in particular,
+where floating-point operations occur in a format with more precision or
+range than the IEEE standard and interchange floating-point types. By
+default, @option{-fexcess-precision=fast} is in effect; this means that
+operations may be carried out in a wider precision than the types specified
+in the source if that would result in faster code, and it is unpredictable
+when rounding to the types specified in the source code takes place.
+When compiling C, if @option{-fexcess-precision=standard} is specified then
+excess precision follows the rules specified in ISO C99; in particular,
both casts and assignments cause values to be rounded to their
semantic types (whereas @option{-ffloat-store} only affects
assignments). This option is enabled by default for C if a strict
@item -fsanitize=kernel-address
@opindex fsanitize=kernel-address
Enable AddressSanitizer for Linux kernel.
-The option enables @option{-fsanitize-address-use-after-scope}.
See @uref{https://github.com/google/kasan/wiki} for more details.
@item -fsanitize=thread
@opindex fbounds-check
For front ends that support it, generate additional code to check that
indices used to access arrays are within the declared range. This is
-currently only supported by the Java and Fortran front ends, where
-this option defaults to true and false respectively.
+currently only supported by the Fortran front end, where this option
+defaults to false.
@item -fcheck-pointer-bounds
@opindex fcheck-pointer-bounds
across different shared libraries. In that case, each of the libraries
as well as the application itself should use the shared @file{libgcc}.
-Therefore, the G++ and GCJ drivers automatically add
-@option{-shared-libgcc} whenever you build a shared library or a main
-executable, because C++ and Java programs typically use exceptions, so
-this is the right thing to do.
+Therefore, the G++ and driver automatically adds @option{-shared-libgcc}
+ whenever you build a shared library or a main executable, because C++
+ programs typically use exceptions, so this is the right thing to do.
If, instead, you use the GCC driver to create shared libraries, you may
find that they are not always linked with the shared @file{libgcc}.
costs at library load time.
However, if a library or main executable is supposed to throw or catch
-exceptions, you must link it using the G++ or GCJ driver, as appropriate
+exceptions, you must link it using the G++ driver, as appropriate
for the languages used in the program, or using the option
@option{-shared-libgcc}, such that it is linked with the shared
@file{libgcc}.
This option instructs the compiler to assume that signed arithmetic
overflow of addition, subtraction and multiplication wraps around
using twos-complement representation. This flag enables some optimizations
-and disables others. This option is enabled by default for the Java
-front end, as required by the Java language specification.
+and disables others.
The options @option{-ftrapv} and @option{-fwrapv} override each other, so using
@option{-ftrapv} @option{-fwrapv} on the command-line results in
@option{-fwrapv} being effective. Note that only active options override, so
performance of the code. Permissible values for this option are:
@samp{generic}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a57},
@samp{cortex-a72}, @samp{cortex-a73}, @samp{exynos-m1}, @samp{falkor},
-@samp{qdf24xx}, @samp{thunderx}, @samp{xgene1}, @samp{vulcan},
-@samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
+@samp{qdf24xx}, @samp{xgene1}, @samp{vulcan}, @samp{thunderx},
+@samp{thunderxt88}, @samp{thunderxt88p1}, @samp{thunderxt81},
+@samp{thunderxt83}, @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
@samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53}, @samp{native}.
The values @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
@table @samp
@opindex mA6
@opindex mARC600
-@item ARC600
@item arc600
Compile for ARC600. Aliases: @option{-mA6}, @option{-mARC600}.
-@item ARC601
@item arc601
@opindex mARC601
Compile for ARC601. Alias: @option{-mARC601}.
-@item ARC700
@item arc700
@opindex mA7
@opindex mARC700
Compile for ARC700. Aliases: @option{-mA7}, @option{-mARC700}.
This is the default when configured with @option{--with-cpu=arc700}@.
-@item ARCEM
@item arcem
Compile for ARC EM.
-@item ARCHS
@item archs
Compile for ARC HS.
+
+@item em
+@opindex em
+Compile for ARC EM cpu with no hardware extension.
+
+@item em4
+@opindex em4
+Compile for ARC EM4 cpu.
+
+@item em4_dmips
+@opindex em4_dmips
+Compile for ARC EM4 DMIPS cpu.
+
+@item em4_fpus
+@opindex em4_fpus
+Compile for ARC EM4 DMIPS cpu with single precision floating point
+extension.
+
+@item em4_fpuda
+@opindex em4_fpuda
+Compile for ARC EM4 DMIPS cpu with single precision floating point and
+double assists instructions.
+
+@item hs
+@opindex hs
+Compile for ARC HS cpu with no hardware extension, except the atomic
+instructions.
+
+@item hs34
+@opindex hs34
+Compile for ARC HS34 cpu.
+
+@item hs38
+@opindex hs38
+Compile for ARC HS38 cpu.
+
+@item hs38_linux
+@opindex hs38_linux
+Compile for ARC HS38 cpu with all hardware extensions on.
+
+@item arc600_norm
+@opindex arc600_norm
+Compile for ARC 600 cpu with norm instruction enabled.
+
+@item arc600_mul32x16
+@opindex arc600_mul32x16
+Compile for ARC 600 cpu with norm and mul32x16 instructions enabled.
+
+@item arc600_mul64
+@opindex arc600_mul64
+Compile for ARC 600 cpu with norm and mul64 instructions enabled.
+
+@item arc601_norm
+@opindex arc601_norm
+Compile for ARC 601 cpu with norm instruction enabled.
+
+@item arc601_mul32x16
+@opindex arc601_mul32x16
+Compile for ARC 601 cpu with norm and mul32x16 instructions enabled.
+
+@item arc601_mul64
+@opindex arc601_mul64
+Compile for ARC 601 cpu with norm and mul64 instructions enabled.
+
+@item nps400
+@opindex nps400
+Compile for ARC 700 on NPS400 chip.
+
@end table
@item -mdpfp
@item -mno-mpy
@opindex mno-mpy
-Do not generate mpy instructions for ARC700.
+Do not generate mpy instructions for ARC700. This instruction is
+deprecated.
@item -mmul32x16
@opindex mmul32x16
@item -mdsp-packa
@opindex mdsp-packa
Passed down to the assembler to enable the DSP Pack A extensions.
-Also sets the preprocessor symbol @code{__Xdsp_packa}.
+Also sets the preprocessor symbol @code{__Xdsp_packa}. This option is
+deprecated.
@item -mdvbf
@opindex mdvbf
Passed down to the assembler to enable the dual viterbi butterfly
-extension. Also sets the preprocessor symbol @code{__Xdvbf}.
+extension. Also sets the preprocessor symbol @code{__Xdvbf}. This
+option is deprecated.
@c ARC700 4.10 extension instruction
@item -mlock
@item -mmac-d16
@opindex mmac-d16
Passed down to the assembler. Also sets the preprocessor symbol
-@code{__Xxmac_d16}.
+@code{__Xxmac_d16}. This option is deprecated.
@item -mmac-24
@opindex mmac-24
Passed down to the assembler. Also sets the preprocessor symbol
-@code{__Xxmac_24}.
+@code{__Xxmac_24}. This option is deprecated.
@c ARC700 4.10 extension instruction
@item -mrtsc
@opindex mrtsc
Passed down to the assembler to enable the 64-bit Time-Stamp Counter
extension instruction. Also sets the preprocessor symbol
-@code{__Xrtsc}.
+@code{__Xrtsc}. This option is deprecated.
@c ARC700 4.10 extension instruction
@item -mswape
@opindex mtelephony
Passed down to the assembler to enable dual and single operand
instructions for telephony. Also sets the preprocessor symbol
-@code{__Xtelephony}.
+@code{__Xtelephony}. This option is deprecated.
@item -mxy
@opindex mxy
built for @w{@code{arc-linux-uclibc}} and @w{@code{arceb-linux-uclibc}}
targets.
-@item -mucb-mcount
-@opindex mucb-mcount
-Instrument with mcount calls as used in UCB code. I.e. do the
-counting in the callee, not the caller. By default ARC instrumentation
-counts in the caller.
-
@item -mvolatile-cache
@opindex mvolatile-cache
Use ordinarily cached memory accesses for volatile references. This is the
system is required to provide these functions. The default is
@option{-mno-apcs-stack-check}, since this produces smaller code.
-@c not currently implemented
-@item -mapcs-float
-@opindex mapcs-float
-Pass floating-point arguments using the floating-point registers. This is
-one of the variants of the APCS@. This option is recommended if the
-target hardware has a floating-point unit or if a lot of floating-point
-arithmetic is going to be performed by the code. The default is
-@option{-mno-apcs-float}, since the size of integer-only code is
-slightly increased if @option{-mapcs-float} is used.
-
@c not currently implemented
@item -mapcs-reentrant
@opindex mapcs-reentrant
@item -mfpu=@var{name}
@opindex mfpu
This specifies what floating-point hardware (or hardware emulation) is
-available on the target. Permissible names are: @samp{vfp}, @samp{vfpv3},
+available on the target. Permissible names are: @samp{vfpv2}, @samp{vfpv3},
@samp{vfpv3-fp16}, @samp{vfpv3-d16}, @samp{vfpv3-d16-fp16}, @samp{vfpv3xd},
-@samp{vfpv3xd-fp16}, @samp{neon}, @samp{neon-fp16}, @samp{vfpv4},
+@samp{vfpv3xd-fp16}, @samp{neon-vfpv3}, @samp{neon-fp16}, @samp{vfpv4},
@samp{vfpv4-d16}, @samp{fpv4-sp-d16}, @samp{neon-vfpv4},
@samp{fpv5-d16}, @samp{fpv5-sp-d16},
@samp{fp-armv8}, @samp{neon-fp-armv8} and @samp{crypto-neon-fp-armv8}.
+Note that @samp{neon} is an alias for @samp{neon-vfpv3} and @samp{vfp}
+is an alias for @samp{vfpv2}.
If @option{-msoft-float} is specified this specifies the format of
floating-point values.
ELF processor-specific section attribute @code{SHF_ARM_PURECODE}. This option
is only available when generating non-pic code for ARMv7-M targets.
+@item -mcmse
+@opindex mcmse
+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}.
@end table
@node AVR Options
Assume that all data in static storage can be accessed by LDS / STS
instructions. This option has only an effect on reduced Tiny devices like
-ATtiny40.
+ATtiny40. See also the @code{absdata}
+@ref{AVR Variable Attributes,variable attribute}.
@item -maccumulate-args
@opindex maccumulate-args
@opindex mpa-risc-2-0
Synonyms for @option{-march=1.0}, @option{-march=1.1}, and @option{-march=2.0} respectively.
+@item -mcaller-copies
+@opindex mcaller-copies
+The caller copies function arguments passed by hidden reference. This
+option should be used with care as it is not compatible with the default
+32-bit runtime. However, only aggregates larger than eight bytes are
+passed by hidden reference and the option provides better compatibility
+with OpenMP.
+
@item -mjump-in-delay
@opindex mjump-in-delay
This option is ignored and provided for compatibility purposes only.
Apply partitioned execution optimizations. This is the default when any
level of optimization is selected.
+@item -msoft-stack
+@opindex msoft-stack
+Generate code that does not use @code{.local} memory
+directly for stack storage. Instead, a per-warp stack pointer is
+maintained explicitly. This enables variable-length stack allocation (with
+variable-length arrays or @code{alloca}), and when global memory is used for
+underlying storage, makes it possible to access automatic variables from other
+threads, or with atomic instructions. This code generation variant is used
+for OpenMP offloading, but the option is exposed on its own for the purpose
+of testing the compiler; to generate code suitable for linking into programs
+using OpenMP offloading, use option @option{-mgomp}.
+
+@item -muniform-simt
+@opindex muniform-simt
+Switch to code generation variant that allows to execute all threads in each
+warp, while maintaining memory state and side effects as if only one thread
+in each warp was active outside of OpenMP SIMD regions. All atomic operations
+and calls to runtime (malloc, free, vprintf) are conditionally executed (iff
+current lane index equals the master lane index), and the register being
+assigned is copied via a shuffle instruction from the master lane. Outside of
+SIMD regions lane 0 is the master; inside, each thread sees itself as the
+master. Shared memory array @code{int __nvptx_uni[]} stores all-zeros or
+all-ones bitmasks for each warp, indicating current mode (0 outside of SIMD
+regions). Each thread can bitwise-and the bitmask at position @code{tid.y}
+with current lane index to compute the master lane index.
+
+@item -mgomp
+@opindex mgomp
+Generate code for use in OpenMP offloading: enables @option{-msoft-stack} and
+@option{-muniform-simt} options, and selects corresponding multilib variant.
+
@end table
@node PDP-11 Options
projects / gcc.git / blobdiff