The langref says the following. But I don't quite understand them. Can
somebody show some C code and how the corresponding debug info will be
encoded in the IR using DILexicalBlockFile? Thanks.
DILexicalBlockFile nodes are used to discriminate between sections of
a lexical block. The file: field can be changed to indicate textual
inclusion, or the discriminator: field can be used to discriminate
between control flow within a single block in the source language.
!0 = !DILexicalBlock(scope: !3, file: !4, line: 7, column: 35)
!1 = !DILexicalBlockFile(scope: !0, file: !4, discriminator: 0)
!2 = !DILexicalBlockFile(scope: !0, file: !4, discriminator: 1)