[RISCV] ld.lld: error: relaxation not converged with openssl

[kraj]

With master as of e33aec8, LLD is unable to link openSSL test binary on RISCV32

Ends up with

riscv32-yoe-linux-musl-ld.lld: error: relaxation not converged

The reproducer is here - https://uclibc.org/~kraj/reproduce.tar

If I use -Wl,--no-relax then it works.

[kraj]

@asb @MaskRay any ideas ?

[MaskRay]

--- i/lld/ELF/Writer.cpp
+++ w/lld/ELF/Writer.cpp
@@ -1536,6 +1536,12 @@ template <class ELFT> void Writer<ELFT>::finalizeAddressDependentContent() {
       Err(ctx) << "address assignment did not converge";
       break;
     }
+    {
+      std::error_code ec;
+      using namespace llvm::sys::fs;
+      llvm::raw_fd_ostream os(("/t/"+Twine(pass)+".map").str(), ec, OF_None);
+      writeMapFile(ctx, os);
+    }

     if (ctx.arg.fixCortexA53Errata843419) {
       if (changed)

We are oscillating between two layouts.

% md5sum /t/*.map
c8bca48289cbeaa3e436deecac1a7ad4  /t/1.map
4562141383fe365290e6f31850785fdc  /t/2.map
99f7929a212f01c1be4ac8cc025ad6bc  /t/3.map
aa739e7a34b852545c0aaca3b09574b3  /t/4.map
ea985e3547b15d2d8cf8f6afc268cfe6  /t/5.map
28b4a075949f35af743f1b9efda826f3  /t/6.map
c710c05c752db8b14ff380a9ca824a98  /t/7.map
28b4a075949f35af743f1b9efda826f3  /t/8.map
...
28b4a075949f35af743f1b9efda826f3  /t/28.map
c710c05c752db8b14ff380a9ca824a98  /t/29.map

When pass is odd, the layout is good; when pass is even,

ld.lld: warning: address assignment did not converge 30
ld.lld: warning: mnt/b/yoe/master/build/tmp/work/riscv32-yoe-linux-musl/openssl/3.3.1/build/test/cmp_msg_test-bin-cmp_msg_test.o:(function test_cmp_create_pollreq: .text+0xe84): relocation R_RISCV_RVC_JUMP out of range: 2048 is not in [-2048, 2047]; references 'set_up'
>>> referenced by cmp_msg_test.c:567 (/usr/src/debug/openssl/3.3.1/../openssl-3.3.1/test/cmp_msg_test.c:567)
>>> defined in mnt/b/yoe/master/build/tmp/work/riscv32-yoe-linux-musl/openssl/3.3.1/build/test/cmp_msg_test-bin-cmp_msg_test.o

% fld.lld @response.txt
ld.lld: error: address assignment did not converge 30
mnt/b/yoe/master/build/tmp/work/riscv32-yoe-linux-musl/openssl/3.3.1/build/test/cmp_msg_test-bin-cmp_msg_test.o:(.text) offset:e6ba6 dest:e73a6 remove0:4 remove1:6
mnt/b/yoe/master/build/tmp/work/riscv32-yoe-linux-musl/openssl/3.3.1/build/test/cmp_msg_test-bin-cmp_msg_test.o:(.text) offset:e6d8c dest:1e6d8c remove0:4 remove1:0

---

Hack that resolves the oscillation issue

--- i/lld/ELF/Arch/RISCV.cpp
+++ w/lld/ELF/Arch/RISCV.cpp
@@ -738,7 +738,9 @@ static void relaxCall(Ctx &ctx, const InputSection &sec, size_t i, uint64_t loc,
   const uint32_t rd = extractBits(insnPair, 32 + 11, 32 + 7);
   const uint64_t dest =
       (r.expr == R_PLT_PC ? sym.getPltVA(ctx) : sym.getVA(ctx)) + r.addend;
-  const int64_t displace = dest - loc;
+  int64_t displace = dest - loc;
+  if (displace < 0)
+    displace -= 4;

   if (rvc && isInt<12>(displace) && rd == 0) {
     sec.relaxAux->relocTypes[i] = R_RISCV_RVC_JUMP;

[llvmbot]

@llvm/issue-subscribers-lld-elf

Author: Khem Raj (kraj)

With master as of e33aec8, LLD is unable to link openSSL test binary on RISCV32

Ends up with

riscv32-yoe-linux-musl-ld.lld: error: relaxation not converged

The reproducer is here - https://uclibc.org/~kraj/reproduce.tar

If I use -Wl,--no-relax then it works.

[MaskRay]

Local hack that helped me get a smaller reproduce
https://gist.github.com/MaskRay/ea0ada43fd8685e8dd0d82caaf097ceb