IR: Change inalloca's grammar a bit
The grammar for LLVM IR is not well specified in any document but seems
to obey the following rules:
- Attributes which have parenthesized arguments are never preceded by commas. This form of attribute is the only one which ever has optional arguments. However, not all of these attributes support optional arguments: 'thread_local' supports an optional argument but 'addrspace' does not. Interestingly, 'addrspace' is documented as being a "qualifier". What constitutes a qualifier? I cannot find a definition.
- Some attributes use a space between the keyword and the value. Examples of this form are 'align' and 'section'. These are always preceded by a comma.
- Otherwise, the attribute has no argument. These attributes do not have a preceding comma.
Sometimes an attribute goes before the instruction, between the
instruction and it's type, or after it's type. 'atomicrmw' has
'volatile' between the instruction and the type while 'call' has 'tail'
preceding the instruction.
With all this in mind, it seems most consistent for 'inalloca' on an
'inalloca' instruction to occur before between the instruction and the
type. Unlike the current formulation, there would be no preceding
comma. The combination 'alloca inalloca' doesn't look particularly
appetizing, perhaps a better spelling of 'inalloca' is down the road.