[Interpreter] Filter out RISC-V +relax feature

[Hahnfeld]

Summary

JITLink for RISC-V does not implement linker relaxation and until now
only ignored the related alignment relocations. However, the logic has
a flaw and it is actually not valid to ignore them. Just disable the
feature to have less problems.

[v.g.vassilev]

This looks reasonable to me. Is there a way we could check when +relax start working to remember to re-add this feature?

clang/lib/Interpreter/IncrementalExecutor.cpp

46

Can you add a comment here why we skip this feature?

This change does not seem riscv-specific. Is that intentional?

[Hahnfeld]

Linker relaxation and proper alignment handling for RISC-V is implemented in https://reviews.llvm.org/D149526, so this isn't needed anymore.

clang/lib/Interpreter/IncrementalExecutor.cpp

 IncrementalExecutor::IncrementalExecutor(llvm::orc::ThreadSafeContext &TSC,
                                          llvm::Error &Err,
                                          const clang::TargetInfo &TI)
     : TSCtx(TSC) {
   using namespace llvm::orc;
   llvm::ErrorAsOutParameter EAO(&Err);
 
   auto JTMB = JITTargetMachineBuilder(TI.getTriple());
-  JTMB.addFeatures(TI.getTargetOpts().Features);
+  for (const auto &F : TI.getTargetOpts().Features) {
+    if (F == "+relax")
+      continue;
+    JTMB.getFeatures().AddFeature(F);
+  }
+
   LLJITBuilder Builder;
   Builder.setJITTargetMachineBuilder(JTMB);
   // Enable debugging of JIT'd code (only works on JITLink for ELF and MachO).
   Builder.setEnableDebuggerSupport(true);
 
   if (auto JitOrErr = Builder.create())
     Jit = std::move(*JitOrErr);
   else {