From 41e546b231af7f317b84d2b342125cea73a1bb46 Mon Sep 17 00:00:00 2001
From: Keno Fischer <kfischer@college.harvard.edu>
Date: Sun, 6 Dec 2015 23:05:38 +0000
Subject: [PATCH] [Verifier] Fix !dbg validation if Scope is the Subprogram

Summary:
We are inserting both Scope and SP into the Seen map and check whether
it was already there in which case we skip the validation (the idea
being that we already checked this Subprogram before). However,
if (Scope == SP) as MDNodes, then inserting the Scope, will trigger
the Seen check causing us to incorrectly not validate this !dbg
attachment. Fix this by not performing the SP Seen check if Scope == SP

Reviewers: pcc, dexonsmith, dblaikie

Subscribers: dblaikie, llvm-commits

Differential Revision: http://reviews.llvm.org/D14697

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254887 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/IR/Verifier.cpp                  |  5 ++++-
 test/CodeGen/X86/2010-05-28-Crash.ll |  2 +-
 test/Verifier/func-dbg.ll            | 25 +++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 test/Verifier/func-dbg.ll

diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index 5cbb597ca26..96b8a779577 100644
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -1814,7 +1814,10 @@ void Verifier::visitFunction(const Function &F) {
         continue;
 
       DISubprogram *SP = Scope ? Scope->getSubprogram() : nullptr;
-      if (SP && !Seen.insert(SP).second)
+
+      // Scope and SP could be the same MDNode and we don't want to skip
+      // validation in that case
+      if (SP && ((Scope != SP) && !Seen.insert(SP).second))
         continue;
 
       // FIXME: Once N is canonical, check "SP == &N".
diff --git a/test/CodeGen/X86/2010-05-28-Crash.ll b/test/CodeGen/X86/2010-05-28-Crash.ll
index 678f1befad1..7967d45c2ee 100644
--- a/test/CodeGen/X86/2010-05-28-Crash.ll
+++ b/test/CodeGen/X86/2010-05-28-Crash.ll
@@ -16,7 +16,7 @@ declare void @llvm.dbg.value(metadata, i64, metadata, metadata) nounwind readnon
 define i32 @bar(i32 %x) nounwind optsize ssp !dbg !8 {
 entry:
   tail call void @llvm.dbg.value(metadata i32 %x, i64 0, metadata !7, metadata !DIExpression()), !dbg !DILocation(scope: !8)
-  tail call void @llvm.dbg.value(metadata i32 1, i64 0, metadata !0, metadata !DIExpression()) nounwind, !dbg !DILocation(scope: !1)
+  tail call void @llvm.dbg.value(metadata i32 1, i64 0, metadata !0, metadata !DIExpression()) nounwind, !dbg !DILocation(scope: !1, inlinedAt: !DILocation(scope: !8))
   %0 = tail call i32 (...) @zoo(i32 1) nounwind, !dbg !12 ; <i32> [#uses=1]
   %1 = add nsw i32 %0, %x, !dbg !13               ; <i32> [#uses=1]
   ret i32 %1, !dbg !13
diff --git a/test/Verifier/func-dbg.ll b/test/Verifier/func-dbg.ll
new file mode 100644
index 00000000000..e56de94d18c
--- /dev/null
+++ b/test/Verifier/func-dbg.ll
@@ -0,0 +1,25 @@
+; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s
+
+define i32 @foo() !dbg !4 {
+entry:
+  ret i32 0, !dbg !6
+}
+
+define i32 @bar() !dbg !5 {
+entry:
+; CHECK: !dbg attachment points at wrong subprogram for function
+  ret i32 0, !dbg !6
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: 0, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
+!1 = !DIFile(filename: "dwarf-test.c", directory: "test")
+!2 = !{}
+!3 = !{!4, !5}
+!4 = distinct !DISubprogram(name: "foo", scope: !0, isDefinition: true)
+!5 = distinct !DISubprogram(name: "bar", scope: !0, isDefinition: true)
+!6 = !DILocation(line: 7, scope: !4)
+!7 = !{i32 2, !"Dwarf Version", i32 3}
+!8 = !{i32 1, !"Debug Info Version", i32 3}
-- 
2.34.1