[llvm] [DebugInfo][RemoveDIs] Find types hidden in DbgRecords (PR #106547)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse created https://github.com/llvm/llvm-project/pull/106547

When serialising to textual IR, there can be constant Values referred to by DbgRecords that don't appear anywhere else, and have types hidden even deeper in side them. Enumerate these when enumerating all types.

Test by Mikael Holmén.

>From 7a084b4e4db71377a538363e6a7d73fc1acbbc10 Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Thu, 29 Aug 2024 13:28:11 +0100
Subject: [PATCH] [DebugInfo][RemoveDIs] Find types hidden in DbgRecords
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When serialising to textual IR, there can be constant Values referred to by
DbgRecords that don't appear anywhere else, and have types hidden even
deeper in side them. Enumerate these when enumerating all types.

Test by Mikael Holmén.
---
 llvm/lib/IR/TypeFinder.cpp                    | 11 +++++
 .../DebugInfo/type-finder-w-dbg-records.ll    | 43 +++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 llvm/test/DebugInfo/type-finder-w-dbg-records.ll

diff --git a/llvm/lib/IR/TypeFinder.cpp b/llvm/lib/IR/TypeFinder.cpp
index 003155a4af4877..d2ffe1ba77b4e3 100644
--- a/llvm/lib/IR/TypeFinder.cpp
+++ b/llvm/lib/IR/TypeFinder.cpp
@@ -88,6 +88,17 @@ void TypeFinder::run(const Module &M, bool onlyNamed) {
         for (const auto &MD : MDForInst)
           incorporateMDNode(MD.second);
         MDForInst.clear();
+
+        // Incorporate types hiding in variable-location information.
+        for (const auto &Dbg : I.getDbgRecordRange()) {
+          // Pick out records that have Values.
+          if (Dbg.getRecordKind() != DbgRecord::Kind::ValueKind)
+            continue;
+          const DbgVariableRecord &DVI = static_cast<const DbgVariableRecord &>(Dbg);
+          for (Value *V : DVI.location_ops()) {
+            incorporateValue(V);
+          }
+        }
       }
   }
 
diff --git a/llvm/test/DebugInfo/type-finder-w-dbg-records.ll b/llvm/test/DebugInfo/type-finder-w-dbg-records.ll
new file mode 100644
index 00000000000000..d2daabc40a3ac3
--- /dev/null
+++ b/llvm/test/DebugInfo/type-finder-w-dbg-records.ll
@@ -0,0 +1,43 @@
+; RUN: opt --passes=verify %s -o - -S | FileCheck %s
+
+;; Test that the type definitions are discovered when serialising to LLVM-IR,
+;; even if they're only present inside a DbgRecord, and thus not normally
+;; visible.
+
+; CHECK: %union.anon = type { %struct.a }
+; CHECK: %struct.a = type { i32 }
+
+; ModuleID = 'bbi-98372.ll'
+source_filename = "bbi-98372.ll"
+
+%union.anon = type { %struct.a }
+%struct.a = type { i32 }
+
+ at d = global [1 x { i16, i16 }] [{ i16, i16 } { i16 0, i16 undef }], align 1
+
+define void @e() {
+entry:
+    #dbg_value(ptr getelementptr inbounds ([1 x %union.anon], ptr @d, i32 0, i32 3), !7, !DIExpression(), !14)
+  ret void, !dbg !15
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "foo.c", directory: "/bar")
+!2 = !{i32 7, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 1}
+!5 = !{i32 7, !"frame-pointer", i32 2}
+!6 = !{!"clang"}
+!7 = !DILocalVariable(name: "f", scope: !8, file: !1, line: 8, type: !12)
+!8 = distinct !DISubprogram(name: "e", scope: !1, file: !1, line: 8, type: !9, scopeLine: 8, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!9 = !DISubroutineType(types: !10)
+!10 = !{null}
+!11 = !{!7}
+!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 16)
+!13 = !DIBasicType(name: "int", size: 16, encoding: DW_ATE_signed)
+!14 = !DILocation(line: 0, scope: !8)
+!15 = !DILocation(line: 8, column: 28, scope: !8)