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Re: Register allocation trouble
Andrew Stubbs schrieb:
On 24/07/17 14:58, Georg-Johann Lay wrote:
Dunno if that works in all situation. For example, when the register
allocator is facing high register pressure and decides to spill the
target register, it uses the constraints of the matched insn.
That would be a memory to memory move, and therefore not valid in any
mov insn on many architectures. Are you sure that's a real thing?
Hard to tell, it depends on many gory details...
If the additional insn is a mov insn that only catches specific cases
by its predicates, then you have definitely a problem (more than 1 mov
insn per mode).
If it has an explicit mem: then the problems are completely different.
For example, it will also match volatile MEMs even for cases when
volatile_ok is false.
In general, it's hard to find test cases which show that something
breaks.
Who generates the additional insn?
Johann
Confused now.
Andrew