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Technical Support
On-Line Manuals
Compiler Reference Guide
Preface
Arm Compiler Tools Overview
armclang Reference
armclang Command-line Options
Summary of armclang command-line options
-C (armclang)
-c (armclang)
-D
-E
-e
-fbare-metal-pie
-fbracket-depth=N
-fcommon, -fno-common
-fdata-sections, -fno-data-sections
-ffast-math, -fno-fast-math
-ffixed-rN
-ffp-mode
-ffunction-sections, -fno-function-sections
-fident, -fno-ident
@file
-fldm-stm, -fno-ldm-stm
-fno-builtin
-fno-inline-functions
-flto, -fno-lto
-fexceptions, -fno-exceptions
-fomit-frame-pointer, -fno-omit-frame-pointer
-fpic, -fno-pic
-fropi, -fno-ropi
-fropi-lowering, -fno-ropi-lowering
-frwpi, -fno-rwpi
-frwpi-lowering, -fno-rwpi-lowering
-fsanitize
-fshort-enums, -fno-short-enums
-fshort-wchar, -fno-short-wchar
-fstack-protector, -fstack-protector-all, -fstack-
-fstrict-aliasing, -fno-strict-aliasing
-fsysv, -fno-sysv
-ftrapv
-fvectorize, -fno-vectorize
-fvisibility
-fwrapv
-g, -gdwarf-2, -gdwarf-3, -gdwarf-4 (armclang)
-I
-include
-L
-l
-M, -MM
-MD, -MMD
-MF
-MG
-MP
-MT
-march
-marm
-masm
-mbig-endian
-mbranch-protection
-mcmodel
-mcmse
-mcpu
-mexecute-only
-mfloat-abi
-mfpu
-mimplicit-it
-mlittle-endian
-mno-neg-immediates
-moutline, -mno-outline
-mpixolib
-munaligned-access, -mno-unaligned-access
-mthumb
-nostdlib
-nostdlibinc
-o (armclang)
-O (armclang)
-pedantic
-pedantic-errors
-Rpass
-S
-save-temps
-shared (armclang)
-std
--target
-U
-u (armclang)
-v (armclang)
--version (armclang)
--version_number (armclang)
--vsn (armclang)
-W
-Wl
-Xlinker
-x (armclang)
-###
Compiler-specific Keywords and Operators
Compiler-specific keywords and operators
__alignof__
__asm
__declspec attributes
__declspec(noinline)
__declspec(noreturn)
__declspec(nothrow)
__inline
__promise
__unaligned
Global named register variables
Compiler-specific Function, Variable, and Type Att
Function attributes
__attribute__((always_inline)) function attribute
__attribute__((cmse_nonsecure_call)) function attr
__attribute__((cmse_nonsecure_entry)) function att
__attribute__((const)) function attribute
__attribute__((constructor(priority))) function at
__attribute__((format_arg(string-index))) function
__attribute__((interrupt("type"))) function attrib
__attribute__((malloc)) function attribute
__attribute__((naked)) function attribute
__attribute__((noinline)) function attribute
__attribute__((nonnull)) function attribute
__attribute__((noreturn)) function attribute
__attribute__((nothrow)) function attribute
__attribute__((pcs("calling_convention"))) functio
__attribute__((pure)) function attribute
__attribute__((section("name"))) function attribut
__attribute__((unused)) function attribute
__attribute__((used)) function attribute
__attribute__((value_in_regs)) function attribute
__attribute__((visibility("visibility_type"))) fun
__attribute__((weak)) function attribute
__attribute__((weakref("target"))) function attrib
Type attributes
__attribute__((aligned)) type attribute
__attribute__((packed)) type attribute
__attribute__((transparent_union)) type attribute
Variable attributes
__attribute__((alias)) variable attribute
__attribute__((aligned)) variable attribute
__attribute__((deprecated)) variable attribute
__attribute__((packed)) variable attribute
__attribute__((section("name"))) variable attribut
__attribute__((unused)) variable attribute
__attribute__((used)) variable attribute
__attribute__((visibility("visibility_type"))) var
__attribute__((weak)) variable attribute
__attribute__((weakref("target"))) variable attrib
Compiler-specific Intrinsics
__breakpoint intrinsic
__current_pc intrinsic
__current_sp intrinsic
__disable_fiq intrinsic
__disable_irq intrinsic
__enable_fiq intrinsic
__enable_irq intrinsic
__force_stores intrinsic
__memory_changed intrinsic
__schedule_barrier intrinsic
__semihost intrinsic
__vfp_status intrinsic
Compiler-specific Pragmas
#pragma clang system_header
#pragma clang diagnostic
#pragma clang section
#pragma once
#pragma pack(...)
#pragma unroll[(n)], #pragma unroll_completely
#pragma weak symbol, #pragma weak symbol1 = symbol
Other Compiler-specific Features
ACLE support
Predefined macros
Inline functions
Half-precision floating-point data types
Half-precision floating-point number format
Half-precision floating-point intrinsics
Library support for _Float16 data type
BFloat16 floating-point number format
TT instruction intrinsics
Non-secure function pointer intrinsics
armclang Integrated Assembler
Syntax of assembly files for integrated assembler
Assembly expressions
Alignment directives
Data definition directives
String definition directives
Floating-point data definition directives
Section directives
Conditional assembly directives
Macro directives
Symbol binding directives
Org directive
AArch32 Target selection directives
AArch64 Target selection directives
Space-filling directives
Type directive
Integrated assembler support for the CSDB instruct
armclang Inline Assembler
Inline Assembly
File-scope inline assembly
Inline assembly statements within a function
Assembly string
Output and input operands
Clobber list
volatile
Inline assembly constraint strings
Constraint modifiers
Constraint codes
Constraint codes common to AArch32 state and AArch
Constraint codes for AArch32 state
Constraint codes for AArch64 state
Using multiple alternative operand constraints
Inline assembly template modifiers
Template modifiers common to AArch32 state and AAr
Template modifiers for AArch32 state
Template modifiers for AArch64 state
Forcing inline assembly operands into specific reg
Symbol references and branches into and out of inl
Duplication of labels in inline assembly statement
armlink Reference
fromelf Reference
armar Reference
armasm Legacy Assembler Reference
Appendixes
Constraint codes
| Non-Confidential |  PDF version | 101754_0613_00_en | ||
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| Home > armclang Reference > armclang Inline Assembler > Inline assembly constraint strings > Constraint codes | ||||
B8.4.2 Constraint codes
Constraint codes define how to pass an operand between assembly code and the surrounding C or C++ code.
There are three categories of constraint codes:
- Constant operands
- You can only use these operands as input operands, and they must be compile-time constants. Use where a value will be used as an immediate operand to an instruction. There are target-specific constraints that accept the immediate ranges suitable for different instructions.
- Register operands
- You can use these operands as both input and output operands. The compiler allocates a register to store the value. As there are a limited number of registers, it is possible to write an inline assembly statement for which there are not enough available registers. In this case, the compiler reports an error. The exact number of available registers varies depending on the target architecture and the optimization level.
- Memory operands
- You can use these operands as both input and output operands. Use them with load and store instructions. Usually a register is allocated to hold a pointer to the operand. As there are a limited number of registers, it is possible to write an inline assembly statement for which there are not enough available registers. In this case, the compiler reports an error. The exact number of available registers can vary depending on the target architecture and the optimization level.
There are some common constraints, which can be used in both AArch32 state and AArch64 state. Other constraints are specific to AArch32 state or AArch64 state. In AArch32 state, there are some constraints that vary depending on the selected instruction set.
| Non-Confidential | PDF version | 101754_0613_00_en |
| Copyright © 2019 Arm Limited or its affiliates. All rights reserved. |
| Home > armclang Reference > armclang Inline Assembler > Inline assembly constraint strings > Constraint codes |
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