[LLVMdev] Possible bug in LLC at -O1

[Anitha B Gollamudi]

On 20 November 2012 15:10, Anitha B Gollamudi <anitha.boyapati at gmail.com> wrote:
> Hi
>
> I am seeing an issue (compiled application seg faults) when llc is
> used at -O1. I first need to triage out which optimization/pass is
> responsible for the seg fault. As such I am following this strategy:
> disable gradually those passes at -O1 which do not exist at -O0. For
> this I used -pass-debug=Structure. [ diff pasted at the end for
> reference]
>
> The problem is I have used almost all -disable-* options from llc
> hidden help. Yet I could not make it equivalent to -O0. Here are my
> questions:
>
>
> 1. For some reason, I am not able to use -regalloc=fast at -O1. Gives
> the following error:
>
>    $ llc  -regalloc=fast -O1 -mcpu=bdver2 test.ll
>     LLVM ERROR: regalloc=... not currently supported with -O0
>
>   How do I switch to "fast" allocator at -O1?
>

<ping>

Not much help on register allocator issue either?


> 2. How do I disable following passes:
>       (a) Optimize for code generation
>       (b) Remove dead machine instructions
>       (c) Optimize machine instruction PHIs
>       (d) Remove unreachable machine basic blocks
>
> (Note that I am already using -disable-machine-dse, cse, -machine-sink
> , lsr ...)
>


-- 
 Anitha