Commit Graph

14 Commits

Author SHA1 Message Date
Rui Ueyama 54d2896852 [ELF] --wrap: Drop __real_ symbol from the symbol table
In D34993, we discussed and concluded that we should drop `__real_
symbol from the symbol table, but I did the opposite in D50569.
This patch is to drop `__real_` symbol.

MaskRay's note: omitting `__real_` is important if it is undefined:
otherwise a subsequent link may error due to the undefined `__real_` in .dynsym

Differential Revision: https://reviews.llvm.org/D51283
2020-05-27 16:58:00 -07:00
Fangrui Song f0374e7db2 [test] lld/test/: change llvm-objdump single-dash long options to double-dash options 2020-03-15 17:48:36 -07:00
Fangrui Song 71e2ca6e32 [llvm-objdump] -d: print `00000000 <foo>:` instead of `00000000 foo:`
The new behavior matches GNU objdump. A pair of angle brackets makes tests slightly easier.

`.foo:` is not unique and thus cannot be used in a `CHECK-LABEL:` directive.
Without `-LABEL`, the CHECK line can match the `Disassembly of section`
line and causes the next `CHECK-NEXT:` to fail.

```
Disassembly of section .foo:

0000000000001634 .foo:
```

Bdragon: <> has metalinguistic connotation. it just "feels right"

Reviewed By: rupprecht

Differential Revision: https://reviews.llvm.org/D75713
2020-03-05 18:05:28 -08:00
Fangrui Song b159906a9a [test] Change llvm-readobj -long-option to --long-option or well-known short options. NFC
Also change some options that have different semantics (cause confusion) in llvm-readelf mode:

-s => -S
-t => --symbols
-sd => --section-data

llvm-svn: 359651
2019-05-01 05:49:01 +00:00
Rui Ueyama 07b4536bb7 Change how we handle -wrap.
We have an issue with -wrap that the option doesn't work well when
renamed symbols get PLT entries. I'll explain what is the issue and
how this patch solves it.

For one -wrap option, we have three symbols: foo, wrap_foo and real_foo.
Currently, we use memcpy to overwrite wrapped symbols so that they get
the same contents. This works in most cases but doesn't when the relocation
processor sets some flags in the symbol. memcpy'ed symbols are just
aliases, so they always have to have the same contents, but the
relocation processor breaks that assumption.

r336609 is an attempt to fix the issue by memcpy'ing again after
processing relocations, so that symbols that are out of sync get the
same contents again. That works in most cases as well, but it breaks
ASan build in a mysterious way.

We could probably fix the issue by choosing symbol attributes that need
to be copied after they are updated. But it feels too complicated to me.

So, in this patch, I fixed it once and for all. With this patch, we no
longer memcpy symbols. All references to renamed symbols point to new
symbols after wrapSymbols() is done.

Differential Revision: https://reviews.llvm.org/D50569

llvm-svn: 340387
2018-08-22 07:02:26 +00:00
Fangrui Song d9c3c1cd9d [ELF] Uniquify --wrap list.
Summary: For --wrap foo --wrap foo, bfd/gold wrap the symbol only once but LLD would rotate it twice.

Reviewers: ruiu, espindola

Subscribers: emaste, arichardson, mgrang, llvm-commits

Differential Revision: https://reviews.llvm.org/D48298

llvm-svn: 334991
2018-06-18 22:32:15 +00:00
Rafael Espindola 97d05f95b9 Copy the visibility in copyFrom.
This is simpler and matches bfd's behavior on the changed test.

llvm-svn: 319248
2017-11-28 23:06:09 +00:00
Rafael Espindola 33e023070f Expand test a bit.
Also make it more reliable by not depending on the order of the
symbols.

This makes the next patch easier to read.

llvm-svn: 319246
2017-11-28 23:03:14 +00:00
Rafael Espindola b45c164fc2 Handle binding in --wrap.
Copying the binding seems reasonable and matches the bfd behavior.

llvm-svn: 319196
2017-11-28 18:02:22 +00:00
Rafael Espindola f07001e5fb Remove unused argument from RUN line.
llvm-svn: 317964
2017-11-11 01:56:45 +00:00
Rafael Espindola 469350810a Refine our --wrap implementation.
Before this patch we would copy foo into real_foo and wrap_foo into
foo. The net result is that __wrap_foo shows up twice in the symbol
table.

With this patch we:

* save a copy of __real_foo before copying foo.
* drop one of the __wrap_foo from the symbol table.
* if __real_foo was not undefined, add a *new* symbol with that content to
  the symbol table.

The net result is that

Anything using foo now uses __wrap_foo
Anything using __real_foo now uses foo.
Anything using __wrap_foo still does.

And the symbol table has foo, __wrap_foo and __real_foo (if defined).

Which I think is the desired behavior.

llvm-svn: 315097
2017-10-06 20:09:34 +00:00
Rafael Espindola cf00d4374e Fix PR33635.
This is a semantic revert of r306036.

We have to change the names, otherwise dynamic relocations will point
to the wrong name.

llvm-svn: 307110
2017-07-05 00:43:18 +00:00
Rui Ueyama 4402a39981 Keep the original symbol name when renamed.
Previously, when symbol A is renamed B, both A and B end up having
the same name. This is because name is a symbol's attribute, and
we memcpy symbols for symbol renaming.

This pathc saves the original symbol name and restore it after memcpy
to keep the original name.

This patch shouldn't change program's meaning, but names in symbol
tables make more sense than before.

llvm-svn: 306036
2017-06-22 17:30:19 +00:00
Rui Ueyama deb154001d ELF: Implement --wrap.
In this patch, all symbols are resolved normally and then wrap options
are applied. Renaming is implemented by mutating `Body` pointers of
Symbols. (As a result, Symtab.find(SymbolName)->getName() may return
a string that's different from SymbolName, but that is by design.
I designed the symbol and the symbol table to allow this kind of
operations.)

http://reviews.llvm.org/D15896

llvm-svn: 257075
2016-01-07 17:20:07 +00:00