Info Catalog as: RISC-V-Options as: RISC-V-Dependent as: RISC-V-Formats

as: RISC-V-Directives

 
 9.37.2 RISC-V Directives
 ------------------------
 
 The following table lists all available RISC-V specific directives.
 
 '.align SIZE-LOG-2'
      Align to the given boundary, with the size given as log2 the number
      of bytes to align to.
 
 '.half VALUE'
 '.word VALUE'
 '.dword VALUE'
      Emits a half-word, word, or double-word value at the current
      position.
 
 '.dtprelword VALUE'
 '.dtpreldword VALUE'
      Emits a DTP-relative word (or double-word) at the current position.
      This is meant to be used by the compiler in shared libraries for
      DWARF debug info for thread local variables.
 
 '.bss'
      Sets the current section to the BSS section.
 
 '.uleb128 VALUE'
 '.sleb128 VALUE'
      Emits a signed or unsigned LEB128 value at the current position.
      This only accepts constant expressions, because symbol addresses
      can change with relaxation, and we don't support relocations to
      modify LEB128 values at link time.
 
 '.option ARGUMENT'
      Modifies RISC-V specific assembler options inline with the assembly
      code.  This is used when particular instruction sequences must be
      assembled with a specific set of options.  For example, since we
      relax addressing sequences to shorter GP-relative sequences when
      possible the initial load of GP must not be relaxed and should be
      emitted as something like
 
           	.option push
           	.option norelax
           	la gp, __global_pointer$
           	.option pop
 
      in order to produce after linker relaxation the expected
 
           	auipc gp, %pcrel_hi(__global_pointer$)
           	addi gp, gp, %pcrel_lo(__global_pointer$)
 
      instead of just
 
           	addi gp, gp, 0
 
      It's not expected that options are changed in this manner during
      regular use, but there are a handful of esoteric cases like the one
      above where users need to disable particular features of the
      assembler for particular code sequences.  The complete list of
      option arguments is shown below:
 
      'push'
      'pop'
           Pushes or pops the current option stack.  These should be used
           whenever changing an option in line with assembly code in
           order to ensure the user's command-line options are respected
           for the bulk of the file being assembled.
 
      'rvc'
      'norvc'
           Enables or disables the generation of compressed instructions.
           Instructions are opportunistically compressed by the RISC-V
           assembler when possible, but sometimes this behavior is not
           desirable.
 
      'pic'
      'nopic'
           Enables or disables position-independent code generation.
           Unless you really know what you're doing, this should only be
           at the top of a file.
 
      'relax'
      'norelax'
           Enables or disables relaxation.  The RISC-V assembler and
           linker opportunistically relax some code sequences, but
           sometimes this behavior is not desirable.
 
 '.insn VALUE'
 '.insn VALUE'
      This directive permits the numeric representation of an
      instructions and makes the assembler insert the operands according
      to one of the instruction formats for '.insn' (
      RISC-V-Formats).  For example, the instruction 'add a0, a1, a2'
      could be written as '.insn r 0x33, 0, 0, a0, a1, a2'.
 
 '.attribute TAG, VALUE'
      Set the object attribute TAG to VALUE.
 
      The TAG is either an attribute number, or one of the following:
      'Tag_RISCV_arch', 'Tag_RISCV_stack_align',
      'Tag_RISCV_unaligned_access', 'Tag_RISCV_priv_spec',
      'Tag_RISCV_priv_spec_minor', 'Tag_RISCV_priv_spec_revision'.
 

Info Catalog as: RISC-V-Options as: RISC-V-Dependent as: RISC-V-Formats