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[ELF] - Eliminate AssertCommand.

Authored by grimar on Apr 9 2018, 4:27 AM.



Currently, LLD supports ASSERT as a separate command.

We support two forms now.

  1. Assign expression-view: . = ASSERT(0x100)

(old GNU ld required it and some scripts in the wild are still using
something like . = ASSERT((_end - _text <= (512 * 1024 * 1024)), "kernel image bigger than KERNEL_IMAGE_SIZE");

  1. Nowadays above is not a mandatory form and command-like form is commonly used:

ASSERT(<expr>, "text);

The return value of the ASSERT is Dot. That was implemented in D30171.
It looks like (2) is just a short version of (1) then.

GNU ld does *not* list ASSERT as a SECTIONS command:

Given above I think we can change ASSERT to be an assignment to Dot.
That makes the rest of the code much simpler.

Diff Detail


Event Timeline

grimar created this revision.Apr 9 2018, 4:27 AM
ruiu added inline comments.Apr 9 2018, 11:16 AM
764 ↗(On Diff #141614)

This change might be okay, but this function name has to be changed.

espindola accepted this revision.Apr 9 2018, 4:17 PM

I am OK with it once a name is agreed on. I would also be OK with readProvideOrAssignment since ASSERT can be viewed as a odd form of assignment.

765 ↗(On Diff #141614)

Add a comment saying that the Assert expression returns ., so this is just ". = .".

This revision is now accepted and ready to land.Apr 9 2018, 4:17 PM
grimar updated this revision to Diff 141815.Apr 10 2018, 3:09 AM
grimar marked 2 inline comments as done.
  • Addressed review comments.
764 ↗(On Diff #141614)

What about readAssignment? Since PROVIDE, HIDDEN and ASSERT are an a variants of assignment command.

grimar added a comment.EditedApr 23 2018, 7:08 AM

Ping. Rui?


It turns out there was one readAssignment already. Not sure how that happened when I posted the patch :/
I'll rename the original readAssignment to readSymbolAssignment as readAssignment introduced in this patch is a wider thing.

This revision was automatically updated to reflect the committed changes.