[cfe-dev] missing info in `-print-before-all -print-after-all`

[Nick Desaulniers via cfe-dev]

Ah, I think my problem is due to loop unrolling.  So I guess the bug
is that loop unrolling doesn't print it's after results, ie.
the is no after corresponding to:
*** IR Dump Before Unroll loops ***
ie.
*** IR Dump After Unroll loops *** (is not printed)

On Tue, Jul 2, 2019 at 10:03 AM Nick Desaulniers
<ndesaulniers at google.com> wrote:
>
> Hello,
> I'm trying to run this through opt to see where a problematic change
> is being made:
> https://gist.github.com/nickdesaulniers/73aef95e9735a50765f654ebdcbb99dd
>
> I'm running this as:
> opt -O2 -print-before-all -print-after-all -verify-each
> generic.get_fixed_ranges.ll -S -o - 2>&1 | less
>
> Near
> *** IR Dump Before MergedLoadStoreMotion ***
> for the function
> @get_fixed_ranges
> I see a problematic callbr instruction:
> callbr void asm sideeffect "1:.byte
> 0x0f,0x1f,0x44,0x00,0\0A\09.pushsection __jump_table,  \22aw\22 \0A\09
> .balign 8 \0A\09.long 1b - ., ${2:l} - . \0A\09 .quad ${0:c} + ${1:c}
> - .\0A\09.popsection \0A\09",
> "i,i,X,~{dirflag},~{fpsr},~{flags}"(%struct.static_key* getelementptr
> inbounds (%struct.tracepoint, %struct.tracepoint*
> @__tracepoint_read_msr, i64 0, i32 1), i1 false, i8*
> blockaddress(@get_fixed_ranges, %20)) #6
>           to label %native_read_msr.exit31.1 [label %49], !srcloc !4
>
> The thing is, I can't find where this was introduced.  I would have
> expected it to be printed AFTER the result of some previous pass, but
> the previous pass looks like `Unroll loops`.
>
> I would have expected some pass to muck this up, at which point it
> would appear in an "AFTER" print out.  What I don't understand is that
> this bad transform first appears in a "BEFORE" transform printout.
>
> Am I holding it wrong?
> --
> Thanks,
> ~Nick Desaulniers



-- 
Thanks,
~Nick Desaulniers