llvm dev - May 2010 - [LLVMdev] Scheduled Instructions go missing

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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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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