[Clang] Don't use crtbegin/crtend when building for musl.

[al45tair]

musl doesn't supply crtbegin/crtend objects, so we don't want to try to link them there.

rdar://123436174

[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Alastair Houghton (al45tair)

Changes

musl doesn't supply crtbegin/crtend objects, so we don't want to try to link them there.

rdar://123436174

---

Full diff: https://github.com/llvm/llvm-project/pull/85089.diff

1 Files Affected:

• (modified) clang/lib/Driver/ToolChains/Gnu.cpp (+4-2)

diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index a9c9d2475809d7..7b7d9194a773ec 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -371,13 +371,15 @@ void tools::gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   const llvm::Triple::ArchType Arch = ToolChain.getArch();
   const bool isOHOSFamily = ToolChain.getTriple().isOHOSFamily();
   const bool isAndroid = ToolChain.getTriple().isAndroid();
+  const bool isMusl = ToolChain.getTriple().isMusl();
   const bool IsIAMCU = ToolChain.getTriple().isOSIAMCU();
   const bool IsVE = ToolChain.getTriple().isVE();
   const bool IsStaticPIE = getStaticPIE(Args, ToolChain);
   const bool IsStatic = getStatic(Args);
   const bool HasCRTBeginEndFiles =
-      ToolChain.getTriple().hasEnvironment() ||
-      (ToolChain.getTriple().getVendor() != llvm::Triple::MipsTechnologies);
+    !isMusl && (ToolChain.getTriple().hasEnvironment() ||
+                (ToolChain.getTriple().getVendor()
+                 != llvm::Triple::MipsTechnologies));
 
   ArgStringList CmdArgs;
 

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[MaskRay]

Thanks for working on musl but I don't think this is correct.
The compiler provides crtbegin/crtend files, not musl.
A musl-cross-make build does use crtbegin/crtend, though technically the files can be empty.
However, there is no point to diverge, and even when crtbegin/crtend files are empty, users can customize them to do other stuff (e.g. specifying the section order).

[al45tair]

The compiler provides crtbegin/crtend files, not musl.

Interesting. Looking at the LLVM repo, it seems compiler-rt might provide them, but I don't believe I have them in spite of building compiler-rt. I'll look at this again and see if maybe I need to tweak my compiler-rt build to get it to generate or install them in the right place.

[al45tair]

(I had assumed that they came from the C library, since that's where crt1.o comes from, but if they don't then it sounds like I just need to build them.)

[al45tair]

Regardless of who provides them, if someone is relying on this then this is the wrong change. Closing.