[LLVMdev] -debug tracing for fast isel

Michael Ilseman milseman at apple.com
Fri Mar 1 15:19:58 PST 2013

On Mar 1, 2013, at 2:37 PM, Eli Bendersky <eliben at google.com> wrote:

> Hello,
> Our SelectionDAG instruction selection mechanism prints out a very
> detailed and useful trace with the -debug option. Conversely, with -O0
> when fast isel is running, there is no equivalent output. Instead,
> debugging has to rely on -fast-isel-verbose2 which just prints out
> statistics at the end of the run and -fast-isel-abort to catch places
> when selection aborted. But even simple tracing of which instructions
> were matched with isel and where it bailed out (along with a simple
> reason for bailing out - i.e. "target could not lower arguments")
> could be very useful.


> Are there any objections to adding such tracing capabilities?
> Everything under DEBUG(), of course, just with the SelectionDAG -debug
> tracing.

That sounds great!

> Eli
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