Quentin Colombet 7f77b29db7 [GlobalISel] Add a type to MachineInstr. ...

We actually need that information only for generic instructions, therefore it
would be nice not to have to pay the extra memory consumption for all
instructions. Especially because a typed non-generic instruction does not make
sense.

The question is then, is it possible to have that information in a union or
something?
My initial thought was that we could have a derived class GenericMachineInstr
with additional information, but in practice it makes little to no sense since
generic MachineInstrs are likely turned into non-generic ones by just switching
the opcode. In other words, we don't want to go through the process of creating
a new, non-generic MachineInstr, object each time we do this switch. The memory
benefit probably is not worth the extra compile time.

Another option would be to keep the type of the MachineInstr in a side table.
This would induce an extra indirection though.

Anyway, I will file a PR to discuss about it and remember we need to come back
to it at some point.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@260558 91177308-0d34-0410-b5e6-96231b3b80d8

2016-02-11 18:22:37 +00:00

..

llvm

[GlobalISel] Add a type to MachineInstr.

2016-02-11 18:22:37 +00:00

llvm-c

Add support for struct in C API test

2016-02-10 00:38:50 +00:00