[LLVMdev] questions about memory dependence analysis

songlh songlh at cs.wisc.edu
Mon Oct 27 02:15:24 PDT 2014

Thanks a lot!



On 2014-10-26 23:05, Wei-Ren Chen wrote:
>>     I have tried memory dependence analysis. I found that load could 
>> have
>> def dependence on another load. How could this happen? And what does
>> clobber dependence mean?
>   For example, we may have two 32-bit register R0 and R1, and [R0,R1] 
> can
> be considered as one 64-bit register X1. When you load X1, this
> operation actually affect R0 and R1. If you have another load R0, we 
> can
> say those load instructions have dependence.
>   From the comment of the source code [1], clobber dependence means the
> content of some memory locations (X) that we cares is modified by a 
> store
> instruction, thus "load X" might have clobber dependence with the store
> instruction.
> HTH,
> chenwj
> [1]
> http://llvm.org/docs/doxygen/html/MemoryDependenceAnalysis_8h_source.html

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