DavidSpickett added a reviewer: DavidSpickett.
DavidSpickett added a comment.
Seems like a valid thing to do.
Is it a problem that maybe you read from address N to N+100 and the problem
address is actually at N+50, not N? I think you might be handling that already
but I didn't read all the logic just your additions. Maybe not an issue because
a lot of this is done in pages of memory, unlikely to be a <10 byte gap where
something fails (and you can manually flush the cache if that somehow happens).
> In this case, the elements often have the value 0, so lldb is trying to read
> memory at address 0, which fails, and the number of reads is quite large.
In this environment I guess they don't have a dynamic loader to have set the
ranges? So in Mac OS userspace, this wouldn't be a problem because the zero
page would be marked as always invalid, but they don't have that luxury.
And there's nothing stopping a bare metal program from mapping memory at 0, so
one can't just say 0 means invalid 100% of the time.
> doesn't address the fact that m_invalid_ranges is intended to track
> inaccessible memory that is invariant during the process lifetime.
Please add this as a comment, will be good to know if/when there are two lists
involved.
================
Comment at: lldb/source/Target/Memory.cpp:157
+ if (IsAddressUnreadable(addr)) {
+ error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64, addr);
+ return 0;
----------------
Should this be more specific like "failed because we know this is unreadable"
or "has previously failed to read"?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D134906/new/
https://reviews.llvm.org/D134906
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