ARM Compiler toolchain v4.1 for µVision Using the Compiler

Using the Inline and Embedded Assemblers of the ARM Compiler
7.18 Expansion of inline assembler load and store instructions
The LDM, STM, LDRD, and STRD instructions might be replaced by equivalent ARM instructions. In
this case the compiler outputs a warning message informing you that it might expand
instructions. The warning can be suppressed with --diag_suppress.
Inline assembly code must be written in such a way that it does not depend on the number of
expected instructions or on the expected execution time for each specified instruction.
Instructions that normally place constraints on pairs of operand registers, such as LDRD and STRD,
are replaced by a sequence of instructions with equivalent functionality and without the
constraints. However, these might be recombined into LDRD and STRD instructions.
All LDM and STM instructions are expanded into a sequence of LDR and STR instructions with
equivalent effect. However, the compiler might subsequently recombine the separate
instructions into an LDM or STM during optimization.
7.18.1 See also
Concepts
• Inline assembler and instruction expansion in C and C++ code on page 7-21
• Compiler support for inline assembly language on page 7-4.
Reference
Compiler Reference:
• --diag_suppress=tag[,tag,...] on page 3-32.
ARM DUI 0375C Copyright © 2007-2008, 2011 ARM. All rights reserved. 7-23
ID061811
Non-Confidential