On 02/22/2016 07:34 AM, Richard Biener wrote:
Hum, but then you get to "inifinite" compiles again when LRA is buggy
or the user presents it with an impossible to handle asm.
Neither should be happening in practice, even an impossible asm should
cause LRA to halt in some way or another.
In practice looping has occurred due to bugs in machine descriptions are
are typically seen during development/porting. Hence the desire to put
it under -fchecking for gcc-6 and possibly implement something smarter
for gcc-7 (where we'd track more precisely whether or not we're making
forward progress).
I don't think that's a good idea - maybe bumping the limit is the way to
go instead?
No, because one just needs to build a longer chain of insns needing
reloading.
30 constraint passes sounds excessive and a sign of a bug to me anyway.
Not really. If you look at the testcase and the chain of reloads, it's
legitimate. Essentially each pass exposes a case where spill a register
in an insn that previously had a register allocated.
Jeff
