[llvm] [DWARF] Emit a minimal line-table for totally empty functions (PR #107267)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -0,0 +1,46 @@
+; RUN: llc %s -o - -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+;; Test that, even though there are no source locations attached to the foo
+;; function, we still give it the start-of-function source location of the
+;; definition line. Otherwise, this function would have no entry in the
+;; line table at all.
+
+; CHECK-LABEL: foo:
+; CHECK-NEXT:   .Lfunc_begin0:
+; CHECK-NEXT:   .file   0 "." "foobar.c"
+; CHECK-NEXT:   .loc    0 1 0
+
+define dso_local noundef i32 @foo(ptr nocapture noundef writeonly %bar) local_unnamed_addr !dbg !10 {
+entry:
+  store i32 0, ptr %bar, align 4
+  ret i32 0
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "foobar.c", directory: ".")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
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OCHyams wrote:

nit: I think we can remove these and their uses

https://github.com/llvm/llvm-project/pull/107267