[LLVMdev] Scheduled Instructions go missing

[Aran Clauson]

All,
	Please dissreguard.

Aran

On Wednesday 19 May 2010 10:13:57 Aran Clauson wrote:
> All,
> 	I'm working on a new scheduler.  I have a basic block
> for which my scheduler generates bad code.  The C code
> looks like
>
> int j, *p;
> if ((j = *p++) != 0) {...}
>
> My scheduler emits (x86, AT&T)
> mov p, %rax
> mov (%rax), %rax
> mov %rax, j
> addq $0x04, p
> je  ...
>
> Notice there is no test instruction.  The default list
> scheduler generates
>
> mov p, %rax
> mov (%rax), %rax
> mov %rax, j
> addq $0x04, p
> test  %rax
> je  ...
>
> The sequence generated by both schedulers after
> scheduling and before emission and they are the same. 
> Specifically, the test instruction is present in both
> sequences at the same point.
> 	I'm thinking that there is something I set in the
> SUnits, but I don't know what that would be.  Any ideas?
>
> Aran


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