[Lldb-commits] [PATCH] D61146: Set a CXXRecordDecl to not be passed in registers if DW_CC_pass_by_reference when loading from DWARF

Frederic Riss via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Wed May 1 10:24:07 PDT 2019

friss added a comment.

Correct me if I'm wrong, but the test seems overly complicated still. We are testing that we can get the return value of a type that needs to be passed by reference. Calling simple free function `Bounds bounds()` should trigger this code path, shouldn't it? I would be interested to know wether we do the right thing when passing such a struct by value in the source code too as Clang doesn't seem to differentiate return values and arguments. Something like:

  // This structure has a non-trivial copy constructor so
  // it needs to be passed by reference.
  struct PassByRef {
    PassByRef() = default;
    PassByRef(const PassByRef &p);
    int x = 11223344;
  PassByRef returnPassByRef() { return PassByRef(); }
  int takePassByRef(PassByRef p) {
      return p.x;
  int main() {
      PassByRef p = returnPassByRef();
      p.x = 42;
      return takePassByRef(returnPassByRef())' // Break here

Break on the return and evaluate `returnPassByRef()` and `takePassByRef(p)`.



More information about the lldb-commits mailing list