GNU Compiler Collection (GCC) Internals: Data Output

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#### 17.20.2 Output of Data

Target Hook: const char * TARGET_ASM_BYTE_OP
Target Hook: const char * TARGET_ASM_ALIGNED_HI_OP
Target Hook: const char * TARGET_ASM_ALIGNED_SI_OP
Target Hook: const char * TARGET_ASM_ALIGNED_DI_OP
Target Hook: const char * TARGET_ASM_ALIGNED_TI_OP
Target Hook: const char * TARGET_ASM_UNALIGNED_HI_OP
Target Hook: const char * TARGET_ASM_UNALIGNED_SI_OP
Target Hook: const char * TARGET_ASM_UNALIGNED_DI_OP
Target Hook: const char * TARGET_ASM_UNALIGNED_TI_OP

  These hooks specify assembly directives for creating certain kinds of integer object. The `TARGET_ASM_BYTE_OP` directive creates a byte-sized object, the `TARGET_ASM_ALIGNED_HI_OP` one creates an aligned two-byte object, and so on. Any of the hooks may be `NULL`, indicating that no suitable directive is available.

  The compiler will print these strings at the start of a new line, followed immediately by the object’s initial value. In most cases, the string should contain a tab, a pseudo-op, and then another tab.

Target Hook: bool TARGET_ASM_INTEGER (rtx x, unsigned int size, int aligned_p)

  The `assemble_integer` function uses this hook to output an integer object. x is the object’s value, size is its size in bytes and aligned_p indicates whether it is aligned. The function should return `true` if it was able to output the object. If it returns false, `assemble_integer` will try to split the object into smaller parts.

  The default implementation of this hook will use the `TARGET_ASM_BYTE_OP` family of strings, returning `false` when the relevant string is `NULL`.

Target Hook: void TARGET_ASM_DECL_END (void)

  Define this hook if the target assembler requires a special marker to terminate an initialized variable declaration.

Target Hook: bool TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA (FILE *file, rtx x)

  A target hook to recognize rtx patterns that `output_addr_const` can’t deal with, and output assembly code to file corresponding to the pattern x. This may be used to allow machine-dependent `UNSPEC`s to appear within constants.

  If target hook fails to recognize a pattern, it must return `false`, so that a standard error message is printed. If it prints an error message itself, by calling, for example, `output_operand_lossage`, it may just return `true`.

Macro: ASM_OUTPUT_ASCII (stream, ptr, len)

  A C statement to output to the stdio stream stream an assembler instruction to assemble a string constant containing the len bytes at ptr. ptr will be a C expression of type `char *` and len a C expression of type `int`.

  If the assembler has a `.ascii` pseudo-op as found in the Berkeley Unix assembler, do not define the macro `ASM_OUTPUT_ASCII`.

Macro: ASM_OUTPUT_FDESC (stream, decl, n)

  A C statement to output word n of a function descriptor for decl. This must be defined if `TARGET_VTABLE_USES_DESCRIPTORS` is defined, and is otherwise unused.

Macro: CONSTANT_POOL_BEFORE_FUNCTION

  You may define this macro as a C expression. You should define the expression to have a nonzero value if GCC should output the constant pool for a function before the code for the function, or a zero value if GCC should output the constant pool after the function. If you do not define this macro, the usual case, GCC will output the constant pool before the function.

Macro: ASM_OUTPUT_POOL_PROLOGUE (file, funname, fundecl, size)

  A C statement to output assembler commands to define the start of the constant pool for a function. funname is a string giving the name of the function. Should the return type of the function be required, it can be obtained via fundecl. size is the size, in bytes, of the constant pool that will be written immediately after this call.

  If no constant-pool prefix is required, the usual case, this macro need not be defined.

Macro: ASM_OUTPUT_SPECIAL_POOL_ENTRY (file, x, mode, align, labelno, jumpto)

  A C statement (with or without semicolon) to output a constant in the constant pool, if it needs special treatment. (This macro need not do anything for RTL expressions that can be output normally.)

  The argument file is the standard I/O stream to output the assembler code on. x is the RTL expression for the constant to output, and mode is the machine mode (in case x is a ‘`const_int`’). align is the required alignment for the value x; you should output an assembler directive to force this much alignment.

  The argument labelno is a number to use in an internal label for the address of this pool entry. The definition of this macro is responsible for outputting the label definition at the proper place. Here is how to do this:

      (*targetm.asm_out.internal_label) (file, "LC", labelno);

  When you output a pool entry specially, you should end with a `goto` to the label jumpto. This will prevent the same pool entry from being output a second time in the usual manner.

  You need not define this macro if it would do nothing.

Macro: ASM_OUTPUT_POOL_EPILOGUE (file funname fundecl size)

  A C statement to output assembler commands to at the end of the constant pool for a function. funname is a string giving the name of the function. Should the return type of the function be required, you can obtain it via fundecl. size is the size, in bytes, of the constant pool that GCC wrote immediately before this call.

  If no constant-pool epilogue is required, the usual case, you need not define this macro.

Macro: IS_ASM_LOGICAL_LINE_SEPARATOR (C, STR)

  Define this macro as a C expression which is nonzero if C is used as a logical line separator by the assembler. STR points to the position in the string where C was found; this can be used if a line separator uses multiple characters.

  If you do not define this macro, the default is that only the character ‘`;`’ is treated as a logical line separator.

Target Hook: const char * TARGET_ASM_OPEN_PAREN
Target Hook: const char * TARGET_ASM_CLOSE_PAREN

  These target hooks are C string constants, describing the syntax in the assembler for grouping arithmetic expressions. If not overridden, they default to normal parentheses, which is correct for most assemblers.

These macros are provided by `real.h` for writing the definitions of `ASM_OUTPUT_DOUBLE` and the like:

Macro: REAL_VALUE_TO_TARGET_SINGLE (x, l)
Macro: REAL_VALUE_TO_TARGET_DOUBLE (x, l)
Macro: REAL_VALUE_TO_TARGET_LONG_DOUBLE (x, l)
Macro: REAL_VALUE_TO_TARGET_DECIMAL32 (x, l)
Macro: REAL_VALUE_TO_TARGET_DECIMAL64 (x, l)
Macro: REAL_VALUE_TO_TARGET_DECIMAL128 (x, l)

  These translate x, of type `REAL_VALUE_TYPE`, to the target’s floating point representation, and store its bit pattern in the variable l. For `REAL_VALUE_TO_TARGET_SINGLE` and `REAL_VALUE_TO_TARGET_DECIMAL32`, this variable should be a simple `long int`. For the others, it should be an array of `long int`. The number of elements in this array is determined by the size of the desired target floating point data type: 32 bits of it go in each `long int` array element. Each array element holds 32 bits of the result, even if `long int` is wider than 32 bits on the host machine.

  The array element values are designed so that you can print them out using `fprintf` in the order they should appear in the target machine’s memory.

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