ahatanak added inline comments.
================ Comment at: clang/test/CodeGenObjC/nontrivial-c-struct-property.m:89 + +// CHECK: call void @__destructor_8_s0(ptr %[[AGG_TMP_ENSURED]]) + ---------------- rjmccall wrote: > ahatanak wrote: > > rjmccall wrote: > > > It looks like we're copying `a` into a temporary and then copying out of > > > that temporary into the argument slot. I don't see any reason the extra > > > copy is required. > > > > > > Also, aren't non-trivial structs consumed as arguments? If so, this > > > would be an over-release. > > It isn't an over-release because, if the receiver isn't nil, temporary > > `AGG_TMP` is destructed in the callee and, if the receiver isn't nil, the > > temporary is destructed in the caller (by the call to > > `@__destructor_8_s0(ptr %[[AGG_TMP]])`). > > > > As you pointed out, the copy isn't needed if the result of the assignment > > isn't used. > Oh, is this second destructor call in conditionally-executed code? Can we > test for that, at least? The first copy constructor call is emitted when `emitPseudoObjectExpr` evaluates the `OpaqueValueExpr` that is the result expression. The second copy constructor call is emitted to copy the argument `*a` to the argument temporary. Since the result expression isn't used in this case, there isn't any reason to emit the first copy constructor call. If Sema marks the `OpaqueValueExpr` for the result expression as unique when the result is unused, CodeGen avoids emitting the first copy constructor. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D136639/new/ https://reviews.llvm.org/D136639 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
