[lld][test] Handle long build path

[thopre]

Summary

LLD test ELF/copy-relocation-zero-nonabs-addr.s fails when the build
path is too long. This is because the DT_NEEDED entry for the shared
library containing object foo encodes the full path to the library. When
the path gets too big, it pushes the beginning of .bss.rel.ro beyond the
expected address of the test and thus the section gets aligned to the
next suitable address.

This commit sets the soname to avoid the build path ending up in the
.dynstr section and thus push .bss.rel.ro further away.

[MaskRay]

lld/test/ELF/copy-relocation-zero-nonabs-addr.s

3

Add --soname=t (or any arbitrary string)

[thopre]

Use --soname instead of changing the CHECK

[thopre]

Update description

[thopre]

Use -l instead of passing library as input file

[thopre]

Sorry, the -soname approach did not solve it on our systems (actually we now have debug build all failing) because it adds a DT_SONAME entry on top of the DT_NEEDED which still contain a full path. How about using -l instead?

[thopre]

In D92598#2433322, @thopre wrote:

Sorry, the -soname approach did not solve it on our systems (actually we now have debug build all failing) because it adds a DT_SONAME entry on top of the DT_NEEDED which still contain a full path. How about using -l instead?

@MaskRay Ping?

[MaskRay]

In D92598#2433322, @thopre wrote:

Sorry, the -soname approach did not solve it on our systems (actually we now have debug build all failing) because it adds a DT_SONAME entry on top of the DT_NEEDED which still contain a full path. How about using -l instead?

You used it wrongly. You should use something like --soname=t instead of --soname=%t (%t will expand to the absolute path).

[thopre]

In D92598#2450552, @MaskRay wrote:

In D92598#2433322, @thopre wrote:

Sorry, the -soname approach did not solve it on our systems (actually we now have debug build all failing) because it adds a DT_SONAME entry on top of the DT_NEEDED which still contain a full path. How about using -l instead?

You used it wrongly. You should use something like --soname=t instead of --soname=%t (%t will expand to the absolute path).

I did, see version 2 of this diff which contained not --soname=t but --soname copy-relocation-zero-nonabs. The effect was *adding* a DT_SONAME entry but it did not change the value of the DT_NEEDED entry.

[MaskRay]

I'll fix and simplify the tests.

The idea is that shared objects for input should set soname. See the description of 0cfa72eaec134693105ec6916aa4692119337a3d

[thopre]

In D92598#2450556, @MaskRay wrote:

I'll fix and simplify the tests.

The idea is that shared objects for input should set soname. See the description of 0cfa72eaec134693105ec6916aa4692119337a3d

Is it "recent" (few months) behavior change? The system on which I tested the --soname is a few month behind master, so that could explain why it didn't work.

[thopre]

In D92598#2450557, @thopre wrote:

In D92598#2450556, @MaskRay wrote:

I'll fix and simplify the tests.

The idea is that shared objects for input should set soname. See the description of 0cfa72eaec134693105ec6916aa4692119337a3d

Is it "recent" (few months) behavior change? The system on which I tested the --soname is a few month behind master, so that could explain why it didn't work.

Doh I see what I did wrong, I changed the wrong ld line (the one creating the executable). I'll fix the testcase.

[thopre]

Use --soname on the right line

[MaskRay]

Fixed by 5d1c723b73aff4a33c4653b9f675cf18dea8c7d6
The tests were a bit confusing so they needed rewrite anyway.

[thopre]

In D92598#2450571, @MaskRay wrote:

Fixed by 5d1c723b73aff4a33c4653b9f675cf18dea8c7d6
The tests were a bit confusing so they needed rewrite anyway.

Thanks a lot. Abandoning revision then.

lld/test/ELF/copy-relocation-zero-nonabs-addr.s

 // REQUIRES: x86
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/copy-relocation-zero-nonabs-addr.s -o %t1.o
-// RUN: ld.lld -Ttext=0 -o %t2.so --script=%p/Inputs/copy-relocation-zero-nonabs-addr.script %t1.o -shared
+// RUN: ld.lld -Ttext=0 --soname=t2.so -o %t2.so --script=%p/Inputs/copy-relocation-zero-nonabs-addr.script %t1.o -shared
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t3.o
 // RUN: ld.lld %t2.so %t3.o -o %t4
 // RUN: llvm-readobj --symbols %t2.so | FileCheck --check-prefix=CHECKSO %s
 // RUN: llvm-readobj --symbols %t4 | FileCheck %s
 
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