[JITLink][RISCV] Consider relaxable call edges for PLT edges

[jobnoorman]

Summary

For linker relaxation (D149526), a new edge kind (CallRelaxable) was
introduced. However, this new kind was not taken into account by
PerGraphGOTAndPLTStubsBuilder_ELF_riscv. This patch fixes this.

[StephenFan]

LGTM.

[Hahnfeld]

Thanks for the patch, this makes it work for me again!

llvm/lib/ExecutionEngine/JITLink/ELF_riscv.cpp

void fixGOTEdge(Edge &E, Symbol &GOTEntry) {
     // Replace the relocation pair (R_RISCV_GOT_HI20, R_RISCV_PCREL_LO12)
     // with (R_RISCV_PCREL_HI20, R_RISCV_PCREL_LO12)
     // Therefore, here just change the R_RISCV_GOT_HI20 to R_RISCV_PCREL_HI20
     E.setKind(R_RISCV_PCREL_HI20);
     E.setTarget(GOTEntry);
   }
 
   void fixPLTEdge(Edge &E, Symbol &PLTStubs) {
-    assert(E.getKind() == R_RISCV_CALL_PLT && "Not a R_RISCV_CALL_PLT edge?");
+    assert((E.getKind() == R_RISCV_CALL || E.getKind() == R_RISCV_CALL_PLT ||
+            E.getKind() == CallRelaxable) &&
+           "Not a PLT edge?");
     E.setKind(R_RISCV_CALL);
     E.setTarget(PLTStubs);
   }
 
   bool isExternalBranchEdge(Edge &E) const {
-    return (E.getKind() == R_RISCV_CALL || E.getKind() == R_RISCV_CALL_PLT) &&
+    return (E.getKind() == R_RISCV_CALL || E.getKind() == R_RISCV_CALL_PLT ||
+            E.getKind() == CallRelaxable) &&
            !E.getTarget().isDefined();
   }
 
 private:
   Section &getGOTSection() const {
     if (!GOTSection)
       GOTSection = &G.createSection("$__GOT", orc::MemProt::Read);
     return *GOTSection;

llvm/test/ExecutionEngine/JITLink/RISCV/ELF_riscv64_got_plt_reloc.s

 # RUN: rm -rf %t && mkdir -p %t
 # RUN: llvm-mc -triple=riscv64 -position-independent -filetype=obj \
 # RUN:     -o %t/elf_riscv64_got_plt_reloc.o %s
 # RUN: llvm-jitlink -noexec \
 # RUN:     -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
 # RUN:     -abs external_func=0x1 -abs external_data=0x2 \
 # RUN:     -check %s %t/elf_riscv64_got_plt_reloc.o
 
+## Run the same tests with relaxation enabled.
+# RUN: llvm-mc -triple=riscv64 -position-independent -filetype=obj \
+# RUN:     -mattr=+relax -o %t/elf_riscv64_got_plt_reloc.o %s
+# RUN: llvm-jitlink -noexec \
+# RUN:     -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN:     -abs external_func=0x1 -abs external_data=0x2 \
+# RUN:     -check %s %t/elf_riscv64_got_plt_reloc.o
 
         .text
         .file   "testcase.c"
 
 # Empty main entry point.
         .globl  main
         .p2align  1
         .type   main,@function