-@c Copyright (C) 1988-2017 Free Software Foundation, Inc.
+@c Copyright (C) 1988-2020 Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
* MIPS Coprocessors:: MIPS coprocessor support and how to customize it.
* PCH Target:: Validity checking for precompiled headers.
* C++ ABI:: Controlling C++ ABI changes.
+* D Language and ABI:: Controlling D ABI changes.
* Named Address Spaces:: Adding support for named address spaces
* Misc:: Everything else.
@end menu
@code{target_has_targetm_common=yes} in @file{config.gcc}; otherwise a
default definition is used.
+Similarly, there is a @code{targetdm} variable for hooks that are
+specific to the D language front end, documented as ``D Target Hook''.
+This is declared in @file{d/d-target.h}, the initializer
+@code{TARGETDM_INITIALIZER} in @file{d/d-target-def.h}. If targets
+initialize @code{targetdm} themselves, they should set
+@code{target_has_targetdm=yes} in @file{config.gcc}; otherwise a default
+definition is used.
+
@node Driver
@section Controlling the Compilation Driver, @file{gcc}
@cindex driver
@hook TARGET_OPTION_INIT_STRUCT
-@hook TARGET_OPTION_DEFAULT_PARAMS
-
@defmac SWITCHABLE_TARGET
Some targets need to switch between substantially different subtargets
during compilation. For example, the MIPS target has one subtarget for
@defmac MAX_OFILE_ALIGNMENT
Biggest alignment supported by the object file format of this machine.
Use this macro to limit the alignment which can be specified using the
-@code{__attribute__ ((aligned (@var{n})))} construct. If not defined,
-the default value is @code{BIGGEST_ALIGNMENT}.
+@code{__attribute__ ((aligned (@var{n})))} construct for functions and
+objects with static storage duration. The alignment of automatic
+objects may exceed the object file format maximum up to the maximum
+supported by GCC. If not defined, the default value is
+@code{BIGGEST_ALIGNMENT}.
On systems that use ELF, the default (in @file{config/elfos.h}) is
the largest supported 32-bit ELF section alignment representable on
-a 32-bit host e.g. @samp{(((uint64_t) 1 << 28) * 8)}.
+a 32-bit host e.g.@: @samp{(((uint64_t) 1 << 28) * 8)}.
On 32-bit ELF the largest supported section alignment in bits is
@samp{(0x80000000 * 8)}, but this is not representable on 32-bit hosts.
@end defmac
If a register has 0 in @code{CALL_USED_REGISTERS}, the compiler
automatically saves it on function entry and restores it on function
exit, if the register is used within the function.
+
+Exactly one of @code{CALL_USED_REGISTERS} and @code{CALL_REALLY_USED_REGISTERS}
+must be defined. Modern ports should define @code{CALL_REALLY_USED_REGISTERS}.
@end defmac
@defmac CALL_REALLY_USED_REGISTERS
Like @code{CALL_USED_REGISTERS} except this macro doesn't require
that the entire set of @code{FIXED_REGISTERS} be included.
(@code{CALL_USED_REGISTERS} must be a superset of @code{FIXED_REGISTERS}).
-This macro is optional. If not specified, it defaults to the value
-of @code{CALL_USED_REGISTERS}.
+
+Exactly one of @code{CALL_USED_REGISTERS} and @code{CALL_REALLY_USED_REGISTERS}
+must be defined. Modern ports should define @code{CALL_REALLY_USED_REGISTERS}.
@end defmac
+@cindex call-used register
+@cindex call-clobbered register
+@cindex call-saved register
+@hook TARGET_FNTYPE_ABI
+
+@hook TARGET_INSN_CALLEE_ABI
+
@cindex call-used register
@cindex call-clobbered register
@cindex call-saved register
@hook TARGET_HARD_REGNO_CALL_PART_CLOBBERED
+@hook TARGET_GET_MULTILIB_ABI_NAME
+
@findex fixed_regs
@findex call_used_regs
@findex global_regs
@hook TARGET_SECONDARY_MEMORY_NEEDED_MODE
+@hook TARGET_SELECT_EARLY_REMAT_MODES
+
@hook TARGET_CLASS_LIKELY_SPILLED_P
@hook TARGET_CLASS_MAX_NREGS
@hook TARGET_DWARF_HANDLE_FRAME_UNSPEC
+@hook TARGET_DWARF_POLY_INDETERMINATE_VALUE
+
@defmac INCOMING_FRAME_SP_OFFSET
A C expression whose value is an integer giving the offset, in bytes,
from the value of the stack pointer register to the top of the stack
debugging information like that provided by DWARF 2.
@end defmac
+@defmac DEFAULT_INCOMING_FRAME_SP_OFFSET
+Like @code{INCOMING_FRAME_SP_OFFSET}, but must be the same for all
+functions of the same ABI, and when using GAS @code{.cfi_*} directives
+must also agree with the default CFI GAS emits. Define this macro
+only if @code{INCOMING_FRAME_SP_OFFSET} can have different values
+between different functions of the same ABI or when
+@code{INCOMING_FRAME_SP_OFFSET} does not agree with GAS default CFI.
+@end defmac
+
@defmac ARG_POINTER_CFA_OFFSET (@var{fundecl})
A C expression whose value is an integer giving the offset, in bytes,
from the argument pointer to the canonical frame address (cfa). The
normally not need to override that default.
@end defmac
-@hook TARGET_STACK_CLASH_PROTECTION_FINAL_DYNAMIC_PROBE
+@hook TARGET_STACK_CLASH_PROTECTION_ALLOCA_PROBE_RANGE
@need 2000
@node Frame Registers
@end defmac
+@defmac DWARF_LAZY_REGISTER_VALUE (@var{regno}, @var{value})
+Define this macro if the target has pseudo DWARF registers whose
+values need to be computed lazily on demand by the unwinder (such as when
+referenced in a CFA expression). The macro returns true if @var{regno}
+is such a register and stores its value in @samp{*@var{value}} if so.
+@end defmac
+
@node Elimination
@subsection Eliminating Frame Pointer and Arg Pointer
@hook TARGET_REF_MAY_ALIAS_ERRNO
+@hook TARGET_TRANSLATE_MODE_ATTRIBUTE
+
@hook TARGET_SCALAR_MODE_SUPPORTED_P
@hook TARGET_VECTOR_MODE_SUPPORTED_P
+@hook TARGET_ARRAY_MODE
+
@hook TARGET_ARRAY_MODE_SUPPORTED_P
@hook TARGET_LIBGCC_FLOATING_MODE_SUPPORTED_P
@hook TARGET_SUPPORTS_SPLIT_STACK
+@hook TARGET_GET_VALID_OPTION_VALUES
+
@node Miscellaneous Register Hooks
@subsection Miscellaneous register hooks
@cindex miscellaneous register hooks
@hook TARGET_STORE_RETURNED_BOUNDS
-@hook TARGET_CHKP_FUNCTION_VALUE_BOUNDS
-
-@hook TARGET_SETUP_INCOMING_VARARG_BOUNDS
-
@node Trampolines
-@section Trampolines for Nested Functions
+@section Support for Nested Functions
+@cindex support for nested functions
@cindex trampolines for nested functions
-@cindex nested functions, trampolines for
-
-A @dfn{trampoline} is a small piece of code that is created at run time
-when the address of a nested function is taken. It normally resides on
-the stack, in the stack frame of the containing function. These macros
-tell GCC how to generate code to allocate and initialize a
-trampoline.
-
-The instructions in the trampoline must do two things: load a constant
-address into the static chain register, and jump to the real address of
-the nested function. On CISC machines such as the m68k, this requires
-two instructions, a move immediate and a jump. Then the two addresses
-exist in the trampoline as word-long immediate operands. On RISC
-machines, it is often necessary to load each address into a register in
-two parts. Then pieces of each address form separate immediate
-operands.
+@cindex descriptors for nested functions
+@cindex nested functions, support for
+
+Taking the address of a nested function requires special compiler
+handling to ensure that the static chain register is loaded when
+the function is invoked via an indirect call.
+
+GCC has traditionally supported nested functions by creating an
+executable @dfn{trampoline} at run time when the address of a nested
+function is taken. This is a small piece of code which normally
+resides on the stack, in the stack frame of the containing function.
+The trampoline loads the static chain register and then jumps to the
+real address of the nested function.
+
+The use of trampolines requires an executable stack, which is a
+security risk. To avoid this problem, GCC also supports another
+strategy: using descriptors for nested functions. Under this model,
+taking the address of a nested function results in a pointer to a
+non-executable function descriptor object. Initializing the static chain
+from the descriptor is handled at indirect call sites.
+
+On some targets, including HPPA and IA-64, function descriptors may be
+mandated by the ABI or be otherwise handled in a target-specific way
+by the back end in its code generation strategy for indirect calls.
+GCC also provides its own generic descriptor implementation to support the
+@option{-fno-trampolines} option. In this case runtime detection of
+function descriptors at indirect call sites relies on descriptor
+pointers being tagged with a bit that is never set in bare function
+addresses. Since GCC's generic function descriptors are
+not ABI-compliant, this option is typically used only on a
+per-language basis (notably by Ada) or when it can otherwise be
+applied to the whole program.
+
+Define the following hook if your backend either implements ABI-specified
+descriptor support, or can use GCC's generic descriptor implementation
+for nested functions.
+
+@hook TARGET_CUSTOM_FUNCTION_DESCRIPTORS
+
+The following macros tell GCC how to generate code to allocate and
+initialize an executable trampoline. You can also use this interface
+if your back end needs to create ABI-specified non-executable descriptors; in
+this case the "trampoline" created is the descriptor containing data only.
+
+The instructions in an executable trampoline must do two things: load
+a constant address into the static chain register, and jump to the real
+address of the nested function. On CISC machines such as the m68k,
+this requires two instructions, a move immediate and a jump. Then the
+two addresses exist in the trampoline as word-long immediate operands.
+On RISC machines, it is often necessary to load each address into a
+register in two parts. Then pieces of each address form separate
+immediate operands.
The code generated to initialize the trampoline must store the variable
parts---the static chain value and the function address---into the
@hook TARGET_TRAMPOLINE_ADJUST_ADDRESS
-@hook TARGET_CUSTOM_FUNCTION_DESCRIPTORS
-
Implementing trampolines is difficult on many machines because they have
separate instruction and data caches. Writing into a stack location
fails to clear the memory in the instruction cache, so when the program
@hook TARGET_LIBC_HAS_FUNCTION
+@hook TARGET_LIBC_HAS_FAST_FUNCTION
+
@defmac NEXT_OBJC_RUNTIME
Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
by default. This calling convention involves passing the object, the selector
@hook TARGET_VECTORIZE_VECTOR_ALIGNMENT_REACHABLE
-@hook TARGET_VECTORIZE_VEC_PERM_CONST_OK
-
-@hook TARGET_VECTORIZE_BUILTIN_CONVERSION
+@hook TARGET_VECTORIZE_VEC_PERM_CONST
@hook TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION
@hook TARGET_VECTORIZE_PREFERRED_SIMD_MODE
-@hook TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_SIZES
+@hook TARGET_VECTORIZE_SPLIT_REDUCTION
+
+@hook TARGET_VECTORIZE_AUTOVECTORIZE_VECTOR_MODES
+
+@hook TARGET_VECTORIZE_RELATED_MODE
@hook TARGET_VECTORIZE_GET_MASK_MODE
+@hook TARGET_VECTORIZE_EMPTY_MASK_IS_EXPENSIVE
+
@hook TARGET_VECTORIZE_INIT_COST
@hook TARGET_VECTORIZE_ADD_STMT_COST
@hook TARGET_SIMT_VF
+@hook TARGET_OMP_DEVICE_KIND_ARCH_ISA
+
@hook TARGET_GOACC_VALIDATE_DIMS
@hook TARGET_GOACC_DIM_LIMIT
@hook TARGET_GOACC_REDUCTION
+@hook TARGET_PREFERRED_ELSE_VALUE
+
@node Anchored Addresses
@section Anchored Addresses
@cindex anchored addresses
branch instruction must be used for some conditional branches. When
this happens, use the machine mode of the condition code register to
record different formats of the condition code register. Modes can
-also be used to record which compare instruction (e.g. a signed or an
+also be used to record which compare instruction (e.g.@: a signed or an
unsigned comparison) produced the condition codes.
If other modes than @code{CCmode} are required, add them to
@hook TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P
+@hook TARGET_ESTIMATED_POLY_VALUE
+
@node Scheduling
@section Adjusting the Instruction Scheduler
@hook TARGET_ASM_RELOC_RW_MASK
+@hook TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC
+
@hook TARGET_ASM_SELECT_SECTION
@defmac USE_SELECT_SECTION_FOR_FUNCTIONS
the jump-table.
@end defmac
+@hook TARGET_ASM_POST_CFI_STARTPROC
+
@hook TARGET_ASM_EMIT_UNWIND_LABEL
@hook TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL
selection in @var{align_jumps} in a @code{JUMP_ALIGN} implementation.
@end defmac
-@hook TARGET_ASM_JUMP_ALIGN_MAX_SKIP
-
@defmac LABEL_ALIGN_AFTER_BARRIER (@var{label})
The alignment (log base 2) to put in front of @var{label}, which follows
a @code{BARRIER}.
define the macro.
@end defmac
-@hook TARGET_ASM_LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP
-
@defmac LOOP_ALIGN (@var{label})
The alignment (log base 2) to put in front of @var{label} that heads
a frequently executed basic block (usually the header of a loop).
selection in @code{align_loops} in a @code{LOOP_ALIGN} implementation.
@end defmac
-@hook TARGET_ASM_LOOP_ALIGN_MAX_SKIP
-
@defmac LABEL_ALIGN (@var{label})
The alignment (log base 2) to put in front of @var{label}.
If @code{LABEL_ALIGN_AFTER_BARRIER} / @code{LOOP_ALIGN} specify a different alignment,
selection in @code{align_labels} in a @code{LABEL_ALIGN} implementation.
@end defmac
-@hook TARGET_ASM_LABEL_ALIGN_MAX_SKIP
-
@defmac ASM_OUTPUT_SKIP (@var{stream}, @var{nbytes})
A C statement to output to the stdio stream @var{stream} an assembler
instruction to advance the location counter by @var{nbytes} bytes.
produce when the user specifies just @option{-g}. Define
this if you have arranged for GCC to support more than one format of
debugging output. Currently, the allowable values are @code{DBX_DEBUG},
-@code{DWARF_DEBUG}, @code{DWARF2_DEBUG},
-@code{XCOFF_DEBUG}, @code{VMS_DEBUG}, and @code{VMS_AND_DWARF2_DEBUG}.
+@code{DWARF2_DEBUG}, @code{XCOFF_DEBUG}, @code{VMS_DEBUG},
+and @code{VMS_AND_DWARF2_DEBUG}.
When the user specifies @option{-ggdb}, GCC normally also uses the
value of this macro to select the debugging output format, but with two
tables, and hence is desirable if it works.
@end defmac
+@defmac DWARF2_ASM_VIEW_DEBUG_INFO
+Define this macro to be a nonzero value if the assembler supports view
+assignment and verification in @code{.loc}. If it does not, but the
+user enables location views, the compiler may have to fallback to
+internal line number tables.
+@end defmac
+
+@hook TARGET_RESET_LOCATION_VIEW
+
@hook TARGET_WANT_DEBUG_PUB_SECTIONS
@hook TARGET_DELAY_SCHED2
@defmac ASM_OUTPUT_DWARF_VMS_DELTA (@var{stream}, @var{size}, @var{label1}, @var{label2})
A C statement to issue assembly directives that create a difference
-between the two given labels in system defined units, e.g. instruction
+between the two given labels in system defined units, e.g.@: instruction
slots on IA64 VMS, using an integer of the given size.
@end defmac
@hook TARGET_INSERT_ATTRIBUTES
+@hook TARGET_HANDLE_GENERIC_ATTRIBUTE
+
@hook TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P
@hook TARGET_OPTION_VALID_ATTRIBUTE_P
@hook TARGET_CXX_DECL_MANGLING_CONTEXT
+@node D Language and ABI
+@section D ABI parameters
+@cindex parameters, d abi
+
+@hook TARGET_D_CPU_VERSIONS
+
+@hook TARGET_D_OS_VERSIONS
+
+@hook TARGET_D_CRITSEC_SIZE
+
@node Named Address Spaces
@section Adding support for named address spaces
@cindex named address spaces
@defmac WORD_REGISTER_OPERATIONS
Define this macro to 1 if operations between registers with integral mode
-smaller than a word are always performed on the entire register.
-Most RISC machines have this property and most CISC machines do not.
+smaller than a word are always performed on the entire register. To be
+more explicit, if you start with a pair of @code{word_mode} registers with
+known values and you do a subword, for example @code{QImode}, addition on
+the low part of the registers, then the compiler may consider that the
+result has a known value in @code{word_mode} too if the macro is defined
+to 1. Most RISC machines have this property and most CISC machines do not.
@end defmac
@hook TARGET_MIN_ARITHMETIC_PRECISION
@hook TARGET_MODE_REP_EXTENDED
+@hook TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P
+
@defmac STORE_FLAG_VALUE
A C expression describing the value returned by a comparison operator
with an integral mode and stored by a store-flag instruction
@hook TARGET_CXX_IMPLICIT_EXTERN_C
-@defmac NO_IMPLICIT_EXTERN_C
-Define this macro if the system header files support C++ as well as C@.
-This macro inhibits the usual method of using system header files in
-C++, which is to pretend that the file's contents are enclosed in
-@samp{extern "C" @{@dots{}@}}.
+@defmac SYSTEM_IMPLICIT_EXTERN_C
+Define this macro if the system header files do not support C++@.
+This macro handles system header files by pretending that system
+header files are enclosed in @samp{extern "C" @{@dots{}@}}.
@end defmac
@findex #pragma
@hook TARGET_EXPAND_BUILTIN
-@hook TARGET_BUILTIN_CHKP_FUNCTION
-@hook TARGET_CHKP_BOUND_TYPE
-@hook TARGET_CHKP_BOUND_MODE
-@hook TARGET_CHKP_MAKE_BOUNDS_CONSTANT
-@hook TARGET_CHKP_INITIALIZE_BOUNDS
-
@hook TARGET_RESOLVE_OVERLOADED_BUILTIN
+@hook TARGET_CHECK_BUILTIN_CALL
+
@hook TARGET_FOLD_BUILTIN
@hook TARGET_GIMPLE_FOLD_BUILTIN
@hook TARGET_GENERATE_VERSION_DISPATCHER_BODY
+@hook TARGET_PREDICT_DOLOOP_P
+
+@hook TARGET_HAVE_COUNT_REG_DECR_P
+
+@hook TARGET_DOLOOP_COST_FOR_GENERIC
+
+@hook TARGET_DOLOOP_COST_FOR_ADDRESS
+
@hook TARGET_CAN_USE_DOLOOP_P
@hook TARGET_INVALID_WITHIN_DOLOOP
lists.
@end defmac
-@defmac MODIFY_JNI_METHOD_CALL (@var{mdecl})
-Define this macro to a C expression representing a variant of the
-method call @var{mdecl}, if Java Native Interface (JNI) methods
-must be invoked differently from other methods on your target.
-For example, on 32-bit Microsoft Windows, JNI methods must be invoked using
-the @code{stdcall} calling convention and this macro is then
-defined as this expression:
-
-@smallexample
-build_type_attribute_variant (@var{mdecl},
- build_tree_list
- (get_identifier ("stdcall"),
- NULL))
-@end smallexample
-@end defmac
-
@hook TARGET_CANNOT_MODIFY_JUMPS_P
-@hook TARGET_BRANCH_TARGET_REGISTER_CLASS
-
-@hook TARGET_BRANCH_TARGET_REGISTER_CALLEE_SAVED
-
@hook TARGET_HAVE_CONDITIONAL_EXECUTION
@hook TARGET_GEN_CCMP_FIRST
@hook TARGET_CONVERT_TO_TYPE
+@hook TARGET_VERIFY_TYPE_CONTEXT
+
@defmac OBJC_JBLEN
This macro determines the size of the objective C jump buffer for the
NeXT runtime. By default, OBJC_JBLEN is defined to an innocuous value.
@end defmac
+@hook TARGET_HAVE_SPECULATION_SAFE_VALUE
+
+@hook TARGET_SPECULATION_SAFE_VALUE
+
@hook TARGET_RUN_TARGET_SELFTESTS
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