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Using the Inline and Embedded Assemblers of the AR
Compiler support for inline assembly language
Inline assembler support in the compiler
Restrictions on inline assembler support in the co
Inline assembly language syntax with the __asm key
Inline assembly language syntax with the asm keywo
Inline assembler rules for compiler keywords __asm
Restrictions on inline assembly operations in C an
Inline assembler register restrictions in C and C+
Inline assembler processor mode restrictions in C
Inline assembler Thumb instruction set restriction
Inline assembler Vector Floating-Point (VFP) restr
Inline assembler instruction restrictions in C and
Miscellaneous inline assembler restrictions in C a
Inline assembler and register access in C and C++
Inline assembler and the # constant expression spe
Inline assembler and instruction expansion in C an
Expansion of inline assembler instructions that us
Expansion of inline assembler load and store instr
Inline assembler effect on processor condition fla
Inline assembler operands in C and C++ code
Inline assembler expression operands in C and C++
Inline assembler register list operands in C and C
Inline assembler intermediate operands in C and C+
Inline assembler function calls and branches in C
Behavior of BL and SVC without optional lists in C
Inline assembler BL and SVC input parameter list i
Inline assembler BL and SVC output value list in C
Inline assembler BL and SVC corrupted register lis
Inline assembler branches and labels in C and C++
Inline assembler and virtual registers
Embedded assembler support in the compiler
Embedded assembler syntax in C and C++
Effect of compiler ARM and Thumb states on embedde
Restrictions on embedded assembly language functio
Compiler generation of embedded assembly language
Access to C and C++ compile-time constant expressi
Differences between expressions in embedded assemb
Manual overload resolution in embedded assembler
__offsetof_base keyword for related base classes i
Compiler-supported keywords for calling class memb
__mcall_is_virtual(D, f)
__mcall_is_in_vbase(D, f)
__mcall_offsetof_vbase(D, f)
__mcall_this_offset(D, f)
__vcall_offsetof_vfunc(D, f)
Calling nonstatic member functions in embedded ass
Calling a nonvirtual member function
Calling a virtual member function
Legacy inline assembler that accesses sp, lr, or p
Accessing sp (r13), lr (r14), and pc (r15) in lega
Differences in compiler support of inline and embe
Compiler User Guide
Expansion of inline assembler instructions that use constants
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| Home > Using the Inline and Embedded Assemblers of the ARM Compiler > Expansion of inline assembler instructions that use constants | |||
The constant in an instruction with a constant operand is not limited to the values permitted by the instruction. Instead, the compiler translates the instruction into a sequence of instructions with the same effect. For example:
ADD r0,r0,#1023
might be translated into:
ADD r0,r0,#1024SUB r0,r0,#1
Another example of expansion possibility is:
MOV rn,0x12345678
With the exception of coprocessor instructions, all ARM instructions
with a constant operand support instruction expansion. In addition,
the MUL instruction can be expanded into a sequence of
adds and shifts when the third operand is a constant.
The effect of updating the CPSR by an expanded
instruction is:
arithmetic instructions set the NZCV flags correctly
logical instructions:
set the NZ flags correctly
do not change the V flag
corrupt the C flag.
See also| Copyright © 2007-2008, 2011-2012 ARM. All rights reserved. | ARM DUI 0375D |
| Non-Confidential | ID062912 |
 PDF version | |
| Home > Using the Inline and Embedded Assemblers of the ARM Compiler > Expansion of inline assembler instructions that use constants |
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