The libz compression library on SystemZ by default makes use of the
platform's hardware-accelerated compression facility. This is much
faster than the regular software implementation, but often results in
slightly different outputs. This causes failures with the
compressed-debug-level test case.
To fix this, run this test while setting the DFLTCC environment
variable to zero, which prevents use of hardware compression and falls
back to the software implementation. (This should not have any effect
on other platforms.)
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D149273
The previous data had the same length with compression levels 1 and 6
for zlib 1.2.8. Adjust the test to work for this library version. I've
also tested this with zlib 1.2.7 and zlib 1.2.11.
Currently LLD always use zlib compression level 6.
This patch changes it to use 1 for -O0, -O1 and 6 for -O2.
It fixes https://bugs.llvm.org/show_bug.cgi?id=44089.
There was also a thread in llvm-dev on this topic:
https://lists.llvm.org/pipermail/llvm-dev/2018-August/125020.html
Here is a table with results of building clang mentioned there:
```
Level Time Size
0 0m17.128s 2045081496 Z_NO_COMPRESSION
1 0m31.471s 922618584 Z_BEST_SPEED
2 0m32.659s 903642376
3 0m36.749s 890805856
4 0m41.532s 876697184
5 0m48.383s 862778576
6 1m3.176s 855251640 Z_DEFAULT_COMPRESSION
7 1m15.335s 853755920
8 2m0.561s 852497560
9 2m33.972s 852397408 Z_BEST_COMPRESSION
```
It shows that it is probably not reasonable to use values greater than 6.
Differential revision: https://reviews.llvm.org/D70658
