[asan][test] Fix use-after-scope-capture test after D148269

[paulkirth]

Summary

After enabling ArgPromotion at lower opt levels, the body of this test
was optimized away, and the CHECK lines no longer functioned.

Setting -O0 is a hammer, but gets the test passing again, until code owners
can find a better solution.

[fmayer]

What's wrong with the fix I commited in D148376? We no longer assert the line.

[paulkirth]

ASAN doesn't trigger at all. There's no error. Main is basically empty, so FileCheck sees an empty stdin and errors out.

This is long after your patch landed:
https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8783802891855939169/overview

I see the same locally.

[paulkirth]

This is a dump of th IR by adding -S -emit-llvm to the command from lit. Main is pretty empty.

; ModuleID = '/usr/local/google/home/paulkirth/llvm-upstream/compiler-rt/test/asan/TestCases/use-after-scope-capture.cpp'
source_filename = "/usr/local/google/home/paulkirth/llvm-upstream/compiler-rt/test/asan/TestCases/use-after-scope-capture.cpp"
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"

@llvm.used = appending global [1 x ptr] [ptr @asan.module_ctor], section "llvm.metadata"
@llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 1, ptr @asan.module_ctor, ptr null }]

; Function Attrs: mustprogress nofree norecurse nosync nounwind sanitize_address willreturn memory(none) uwtable
define dso_local noundef i32 @main() local_unnamed_addr #0 personality ptr @__gxx_personality_v0 !dbg !10 {
entry:
  ret i32 0, !dbg !14
}

declare i32 @__gxx_personality_v0(...)

declare void @__asan_init()

; Function Attrs: nounwind uwtable
define internal void @asan.module_ctor() #1 {
  call void @__asan_init()
  call void @__asan_version_mismatch_check_v8()
  ret void
}

declare void @__asan_version_mismatch_check_v8()

attributes #0 = { mustprogress nofree norecurse nosync nounwind sanitize_address willreturn memory(none) uwtable "disable-tail-calls"="true" "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" }
attributes #1 = { nounwind uwtable "frame-pointer"="all" }

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
!llvm.ident = !{!9}

!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "Fuchsia clang version 17.0.0 ([e-mail]:llvm/llvm-project.git e3b378fad95196c721fc2258f325591f21595c81)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "/usr/local/google/home/paulkirth/llvm-upstream/compiler-rt/test/asan/TestCases/use-after-scope-capture.cpp", directory: "/usr/local/google/home/paulkirth/llvm-upstream/build", checksumkind: CSK_MD5, checksum: "5a3c1e2ee765a8c5617c785e93f76014")
!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 = !{!"Fuchsia clang version 17.0.0 ([e-mail]:llvm/llvm-project.git e3b378fad95196c721fc2258f325591f21595c81)"}
!10 = distinct !DISubprogram(name: "main", scope: !11, file: !11, line: 5, type: !12, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
!11 = !DIFile(filename: "compiler-rt/test/asan/TestCases/use-after-scope-capture.cpp", directory: "/usr/local/google/home/paulkirth/llvm-upstream", checksumkind: CSK_MD5, checksum: "5a3c1e2ee765a8c5617c785e93f76014")
!12 = !DISubroutineType(types: !13)
!13 = !{}
!14 = !DILocation(line: 18, column: 1, scope: !10)

[fmayer]

In D148396#4270351, @paulkirth wrote:

ASAN doesn't trigger at all. There's no error. Main is basically empty, so FileCheck sees an empty stdin and errors out.

This is long after your patch landed:
https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8783802891855939169/overview

I see the same locally.

Weird, it fixed it locally for me. Not sure why.

compiler-rt/test/asan/TestCases/use-after-scope-capture.cpp

-// RUN: %clangxx_asan -O1 %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O0 %s -o %t && not %run %t 2>&1 | FileCheck %s
 
 #include <functional>
 
 int main() {
   std::function<int()> f;
   {
     int x = 0;
     f = [&x]() __attribute__((noinline)) {