[PATCH] D105528: [RuntimeDyldChecker] Support offset in decode_operand expr

[Lang Hames via Phabricator via llvm-commits]

lhames added a comment.

In D105528#2861144 <https://reviews.llvm.org/D105528#2861144>, @jrtc27 wrote:

> Why can't you just add a label for the instruction you want to test?

Actually I really like the idea of allowing offsets here. Avoiding artificial labels has two benefits: improved readability, and clearer layout control on MachO where labels implicitly start new subsections.

> This is just (named_data - test_pcrel32) & 0xfff sign-extended from 12 to 64 bits. The + 0x800 for the HI is to compensate for the sign extension for the LO, feeding it back into the LO calculation is backwards and results in circular reasoning.

I don't know RISCV, so I defer to Jessica here.

Side note: Some comparisons may be easier to express with the bit-slicing operator. E.g. this example from MachO_arm64_relocations.s:

  # jitlink-check: decode_operand(test_local_call, 0)[25:0] = (named_func - test_local_call)[27:2]
          .globl  test_local_call
          .p2align  2
  test_local_call:
          bl   named_func

Please address Jessica's feedback, but otherwise LGTM. Thanks Stephen!



================
Comment at: llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp:240-247
+    case BinOpToken::Add:
+    case BinOpToken::Sub: {
+      EvalResult Number;
+      std::tie(Number, RemainingExpr) = evalNumberExpr(RemainingExpr);
+      Offset =
+          BinOp == BinOpToken::Add ? Number.getValue() : -Number.getValue();
+      break;
----------------
You should error out for the other binop tokens with an unexpected token error.


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https://reviews.llvm.org/D105528