RealView Compilation Tools Compiler Reference Guide - ARM ...

Compiler Command-line Options
See also
• -Aopt on page 2-2
• -Lopt on page 2-52
• --via=filename on page 2-92.
2.1.110 --split_ldm
This option instructs the compiler to split LDM and STM instructions into two or more LDM
or STM instructions.
When --split_ldm is selected, the maximum number of register transfers for an LDM or
STM instruction is limited to:
• five, for all STMs
• five, for LDMs that do not load the PC
• four, for LDMs that load the PC.
Where register transfers beyond these limits are required, multiple LDM or STM
instructions are used.
Note
This option is deprecated and will be removed in the next release.
Usage
The --split_ldm option can be used to reduce interrupt latency on ARM systems that:
• do not have a cache or a write buffer, for example, a cacheless ARM7TDMI
• use zero-wait-state, 32-bit memory.
Note
Using --split_ldm increases code size and decreases performance slightly.
Restrictions
• Inline assembler LDM and STM instructions are split by default when --split_ldm is
used. However, the compiler might subsequently recombine the separate
instructions into an LDM or STM.
• VFP FLDM or FSTM instructions are not split when --split_ldm is used.
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