[Tests] Require zlib for zstd tests

[mariusz-sikora-at-amd]

Summary

Tests may fail on system without zlib

[jhenderson]

Could you explain a bit more about how these tests fail without zlib? I don't think they should rely on it, so if there are failures it means there's either a problem with the test or the implementation.

[mariusz-sikora-at-amd]

Sorry for not providing more details.
These tests may fail if zlib is installed on the system, but front end is explicitly disabling LLVM_ENABLE_ZLIB in cmake, then LIT tests will fail with information that LLVM_ENABLE_ZLIB has been disabled.

[jhenderson]

I'm fairly confident this is the wrong fix for the problem. ZSTD compression shouldn't require ZLIB support (and similarly ZLIB compression shouldn't require ZSTD support). Without looking too hard at the problem, my guess is that there's a bug in the check for whether the --compress-debug-sections option is supported or not. There may also be a lit bug, in that the REQUIRES directive for these compression formats should be based on what happened at cmake configuration time, not (only) on what's installed on the system, but I'm not really sure.

I haven't been involved with the recent compression changes really, so I've added a few people who have.

[MaskRay]

In D135437#3848749, @jhenderson wrote:

I'm fairly confident this is the wrong fix for the problem. ZSTD compression shouldn't require ZLIB support (and similarly ZLIB compression shouldn't require ZSTD support). Without looking too hard at the problem, my guess is that there's a bug in the check for whether the --compress-debug-sections option is supported or not. There may also be a lit bug, in that the REQUIRES directive for these compression formats should be based on what happened at cmake configuration time, not (only) on what's installed on the system, but I'm not really sure.

I haven't been involved with the recent compression changes really, so I've added a few people who have.

I agree with the analysis. https://reviews.llvm.org/D135744 is the proper fix.

The test/MC/ELF test works as intended, even if I enable zstd and disable zlib.

[mariusz-sikora-at-amd]

Closing this review. This issue will be fixed in review : https://reviews.llvm.org/D135744

llvm/test/MC/ELF/compress-debug-sections-zstd.s

 # REQUIRES: zstd
+# REQUIRES: zlib
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64 -compress-debug-sections=zstd %s -o %t
 # RUN: llvm-readelf -S %t | FileCheck %s --check-prefix=SEC
 # RUN: llvm-objdump -s %t | FileCheck %s
 
 ## Check that the large debug sections .debug_line and .debug_frame are compressed
 ## and have the SHF_COMPRESSED flag.
 # SEC: .nonalloc     PROGBITS [[#%x,]] [[#%x,]] [[#%x,]] 00     0 0  1

llvm/test/tools/llvm-objcopy/ELF/compress-debug-sections-zstd.test

 # REQUIRES: zstd
+# REQUIRES: zlib
 ## Test --compress-debug-sections=zstd and decompression.
 
 # RUN: yaml2obj %p/Inputs/compress-debug-sections.yaml -o %t && llvm-objcopy %t
 # RUN: llvm-objcopy --compress-debug-sections=zstd %t %t-zstd
 # RUN: llvm-objcopy --decompress-debug-sections %t-zstd %t-de
 # RUN: cmp %t %t-de
 
 # RUN: llvm-readelf -S -r -x .debug_foo %t-zstd | FileCheck %s --check-prefixes=CHECK,COMPRESSED