[all-commits] [llvm/llvm-project] ada137: [MC] Remove unneeded MCDataFragment check from Att...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ada137a4c2a292c34927f0f22bd4c6fba4d3df87
      https://github.com/llvm/llvm-project/commit/ada137a4c2a292c34927f0f22bd4c6fba4d3df87
  Author: Fangrui Song <i at maskray.me>
  Date:   2023-06-18 (Sun, 18 Jun 2023)

  Changed paths:
    M llvm/lib/MC/MCExpr.cpp

  Log Message:
  -----------
  [MC] Remove unneeded MCDataFragment check from AttemptToFoldSymbolOffsetDifference

If FA == FB, we can use SA.getOffset() - SB.getOffset() even if FA is
not a MCDataFragment, as the only case this can be problematic
(different offsets for a variable-size fragment) is invalid/unreachable.
If FA != FB, the `if (FI->getKind() != MCFragment::FT_Data)` check below
can bail out correctly.

This change will help Mach-O fold more expressions. For ELF this is NFC,
unless evaluateFixup has a bug that would evaluate an expression
differently.