From 37676b50b62ac849876c7b9f55fb63a5f9776020 Mon Sep 17 00:00:00 2001
From: Davide Italiano <davide@freebsd.org>
Date: Mon, 17 Dec 2018 01:42:39 +0000
Subject: [PATCH] [EarlyCSE] If DI can't be salvaged, mark it as unavailable.

Fixes PR39874.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@349323 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/EarlyCSE.cpp           |  3 +-
 test/Transforms/EarlyCSE/debug-info-undef.ll | 69 ++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/EarlyCSE/debug-info-undef.ll

diff --git a/lib/Transforms/Scalar/EarlyCSE.cpp b/lib/Transforms/Scalar/EarlyCSE.cpp
index 11009d501a9..1f09979b338 100644
--- a/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -812,7 +812,8 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
         LLVM_DEBUG(dbgs() << "Skipping due to debug counter\n");
         continue;
       }
-      salvageDebugInfo(*Inst);
+      if (!salvageDebugInfo(*Inst))
+        replaceDbgUsesWithUndef(Inst);
       removeMSSA(Inst);
       Inst->eraseFromParent();
       Changed = true;
diff --git a/test/Transforms/EarlyCSE/debug-info-undef.ll b/test/Transforms/EarlyCSE/debug-info-undef.ll
new file mode 100644
index 00000000000..4615aa264b6
--- /dev/null
+++ b/test/Transforms/EarlyCSE/debug-info-undef.ll
@@ -0,0 +1,69 @@
+; RUN: opt -S %s -early-cse | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+@a = global i8 25, align 1, !dbg !0
+
+define signext i16 @b() !dbg !12 {
+entry:
+  call void @llvm.dbg.value(metadata i16 23680, metadata !17, metadata !DIExpression()), !dbg !18
+  %0 = load i8, i8* @a, align 1, !dbg !19, !tbaa !20
+  %conv = sext i8 %0 to i16, !dbg !19
+
+; CHECK: call void @llvm.dbg.value(metadata i16 undef, metadata !17, metadata !DIExpression()), !dbg !18
+; CHECK-NEXT:  call i32 (...) @optimize_me_not()
+
+  call void @llvm.dbg.value(metadata i16 %conv, metadata !17, metadata !DIExpression()), !dbg !18
+  %call = call i32 (...) @optimize_me_not(), !dbg !23
+  %1 = load i8, i8* @a, align 1, !dbg !24, !tbaa !20
+  %conv1 = sext i8 %1 to i16, !dbg !24
+  ret i16 %conv1, !dbg !25
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare i32 @optimize_me_not(...)
+
+define i32 @main() !dbg !26 {
+entry:
+  %call = call signext i16 @b(), !dbg !30
+  ret i32 0, !dbg !31
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9, !10}
+!llvm.ident = !{!11}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 8.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: GNU)
+!3 = !DIFile(filename: "patatino.c", directory: "/Users/davide/llvm-monorepo/llvm-mono/build/bin")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{i32 7, !"PIC Level", i32 2}
+!11 = !{!"clang version 8.0.0 "}
+!12 = distinct !DISubprogram(name: "b", scope: !3, file: !3, line: 2, type: !13, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !16)
+!13 = !DISubroutineType(types: !14)
+!14 = !{!15}
+!15 = !DIBasicType(name: "short", size: 16, encoding: DW_ATE_signed)
+!16 = !{!17}
+!17 = !DILocalVariable(name: "i", scope: !12, file: !3, line: 3, type: !15)
+!18 = !DILocation(line: 3, column: 9, scope: !12)
+!19 = !DILocation(line: 4, column: 7, scope: !12)
+!20 = !{!21, !21, i64 0}
+!21 = !{!"omnipotent char", !22, i64 0}
+!22 = !{!"Simple C/C++ TBAA"}
+!23 = !DILocation(line: 5, column: 3, scope: !12)
+!24 = !DILocation(line: 6, column: 10, scope: !12)
+!25 = !DILocation(line: 6, column: 3, scope: !12)
+!26 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 8, type: !27, scopeLine: 8, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!27 = !DISubroutineType(types: !28)
+!28 = !{!29}
+!29 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!30 = !DILocation(line: 8, column: 14, scope: !26)
+!31 = !DILocation(line: 8, column: 19, scope: !26)
-- 
2.11.0