[IR] Add a test case for stripDebugLocFromLoopID

[kazu]

Summary

This patch adds a test case for
5a68d6721d042d57d1b2fef5d1b2e40a1260c169.

The credit for the test case goes to David.

Fixes https://github.com/llvm/llvm-project/issues/57557

[aprantl]

llvm/test/DebugInfo/no-dicompileunit.ll

4

Can you also add a positive test? E.g.: CHECK: define {{.*}}@main otherwise this test will pass even if opt is a symlink to /bin/true

[kazu]

Add a positive test.

[kazu]

Please take a look. Thanks!

[kazu]

I'd appreciate a review. Thanks!

[kazu]

Please take a look. Thanks!

llvm/test/DebugInfo/no-dicompileunit.ll

+; RUN: opt -S -strip-debug -disable-debug-info-type-map < %s | FileCheck %s
+
+; CHECK: define {{.*}}@main
+; CHECK-NOT: DICompileUnit
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: noinline nounwind optnone uwtable
+define dso_local i32 @main() #0 !dbg !10 {
+entry:
+  %retval = alloca i32, align 4
+  %i = alloca i32, align 4
+  store i32 0, ptr %retval, align 4
+  store i32 0, ptr %i, align 4, !dbg !13
+  br label %for.cond, !dbg !13
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %0 = load i32, ptr %i, align 4, !dbg !13
+  %cmp = icmp slt i32 %0, 1, !dbg !13
+  br i1 %cmp, label %for.body, label %for.end, !dbg !13
+
+for.body:                                         ; preds = %for.cond
+  br label %for.inc, !dbg !14
+
+for.inc:                                          ; preds = %for.body
+  %1 = load i32, ptr %i, align 4, !dbg !13
+  %inc = add nsw i32 %1, 1, !dbg !13
+  store i32 %inc, ptr %i, align 4, !dbg !13
+  br label %for.cond, !dbg !13, !llvm.loop !15
+
+for.end:                                          ; preds = %for.cond
+  ret i32 0, !dbg !22
+}
+
+attributes #0 = { noinline nounwind optnone uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 16.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "foo.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, !"frame-pointer", i32 2}
+!9 = !{!"clang version 16.0.0"}
+!10 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !11, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !12)
+!11 = !DISubroutineType(types: !12)
+!12 = !{}
+!13 = !DILocation(line: 5, scope: !10)
+!14 = !DILocation(line: 7, scope: !10)
+!15 = distinct !{!15, !13, !14, !16, !17, !18}
+!16 = !{!"llvm.loop.mustprogress"}
+!17 = !{!"llvm.loop.vectorize.enable", i1 true}
+!18 = !{!"llvm.loop.vectorize.followup_all", !19}
+!19 = distinct !{!19, !13, !14, !16, !20, !21}
+!20 = !{!"llvm.loop.isvectorized"}
+!21 = !{!"llvm.loop.unroll.count", i32 1}
+!22 = !DILocation(line: 8, scope: !10)