Allow gep instructions to accept bare Python integers as indices.

[trbabb]

New feature: gep instructions can accept Python integers as indices, instead of requiring the client code to tediously construct ir.Constants around each index.

For example:

int32 = ir.IntType(32)
builder.gep(my_object, [int32(5), int32(0), int32(3)])

becomes

builder.gep(my_object, [5, 0, 3])

The width of each converted integer will be chosen to be the smallest number of 8-bit bytes that is a power of two and can represent the value.

It is permissible to intermix Python integers with IR instructions in the index list.

[esc]

@trbabb thank you for submitting this to the Numba issue tracker. I have added this to the 0.37.0 milestone. Also, it seems like there are some remaining flake8 issues to be resolved.

[trbabb]

Fixed the stray whitespace, but the overlong line is inlined SSA, which that file is already full of, and which I can't really truncate. What do I need to do to prevent that from failing the test?

[esc]

Fixed the stray whitespace, but the overlong line is inlined SSA, which that file is already full of, and which I can't really truncate. What do I need to do to prevent that from failing the test?

This should help: https://flake8.pycqa.org/en/3.1.1/user/ignoring-errors.html#in-line-ignoring-errors

[gmarkall]

Many thanks for the PR!

I like the idea of this change, but I think the changes to the tests need modifying. Instead of modifying an existing test case, could you add a new test case that tests accepting integers for the gep instruction (and a mix of integers and ir.Constant values) please?

[gmarkall]

Suggested change

	i_type = types.IntType(bits)
	i = i_type(i)
	i = types.IntType(bits)(i)

[gmarkall]

@trbabb Many thanks for the PR and your efforts so far!

I'm spending some time going through the llvmlite PR backlog, and I have a couple of questions on this PR:

• Do you plan to continue with this PR? If it's difficult for you to work on this PR for any reason, please let me know and we can look into whether / how to proceed further.
• If you're keen to continue - do you need any further advice on how to proceed?