[lld] [lld][LoongArch] Relax call36/tail36: R_LARCH_CALL36 (PR #123576)

[Fangrui Song via llvm-commits]

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@@ -830,6 +832,37 @@ static void relaxPCHi20Lo12(Ctx &ctx, const InputSection &sec, size_t i,
   remove = 4;
 }
 
+// Relax code sequence.
+// From:
+//   pcaddu18i $ra, %call36(foo)
+//   jirl $ra, $ra, 0
+// To:
+//   b/bl foo
+static void relaxCall36(Ctx &ctx, const InputSection &sec, size_t i,
+                        uint64_t loc, Relocation &r, uint32_t &remove) {
+  const uint64_t dest =
+      (r.expr == R_PLT_PC ? r.sym->getPltVA(ctx) : r.sym->getVA(ctx)) +
+      r.addend;
+
+  const int64_t displace = dest - loc;
+  // Check if the displace aligns 4 bytes or exceeds the range of b[l].
+  if ((displace & 0x3) != 0 || !isInt<28>(displace))
+    return;
+
+  const uint32_t nextInsn = read32le(sec.content().data() + r.offset + 4);
----------------
MaskRay wrote:

I still prefer that we remove the checks. We should avoid assert, when it is actually reachable.

If BFD wants to be guard against malformed input, that's ok. It's fine to diverge from it.

https://github.com/llvm/llvm-project/pull/123576