On Mon, Jul 27, 2020 at 09:53:31AM -0600, Martin Sebor via Gcc-patches wrote: > Return a pointer P to a NUL-terminated string containing > the sequence of bytes corresponding to the representation > of the object referred to by SRC (or a subsequence of such > bytes within it if SRC is a reference to an initialized > constant array plus some constant offset). > > I.e., c_getstr returns a STRING_CST for arbitrary non-string > constants. This enables optimizations like the by-pieces > expansion of calls to raw memory functions like memcpy, or > the folding of other raw memory calls like memchr with non- > string arguments. > > c_getstr relies on string_constant for that. Restricting > the latter function to just character types prevents these > optimizations for zero-initialized constants of other types. > A test case that shows the difference to the by-pieces > expansion goes something like this:
Having STRING_CST in the compiler with arbitrary array type is IMHO a very bad idea, so if you want something like that, you should come up with a different representation for that, not STRING_CSTs. Because most of the compiler assumes STRING_CSTs are what it says, string literals where elements are some kind of characters, don't have to be narrow, but better should be integral. Maybe returning a CONSTRUCTOR with no elements with the right type is a better idea for that, that in the compiler stands for zero initialized aggregate. Jakub