+; RUN: opt < %s -S -simplifycfg | FileCheck %s
+
+; SimplifyCFG can hoist any common code in the 'then' and 'else' blocks to
+; the 'if' basic block.
+;
+; For the special case, when hoisting the terminator instruction, its debug
+; location keep references to its basic block, causing the debug information
+; to become ambiguous. It causes the debugger to display unreached lines.
+
+; Change the debug location associated with the hoisted instruction, to
+; the debug location from the insertion point in the 'if' block.
+
+; The insertion point is the previous non-debug instruction before the
+; terminator in the parent basic block of the hoisted instruction.
+
+; IR with '-g':
+;
+; [...]
+; %frombool = zext i1 %cmp to i8, !dbg !26
+; call void @llvm.dbg.value(metadata i8 %frombool, metadata !15, metadata !DIExpression()), !dbg !26
+; call void @llvm.dbg.value(metadata i32 0, metadata !17, metadata !DIExpression()), !dbg !27
+; br i1 %cmp, label %if.then, label %if.else
+; [...]
+;
+; Insertion point is: %frombool = zext i1 %cmp to i8, !dbg !26
+
+; IR generated with:
+; clang -S -g -gno-column-info -O2 -emit-llvm pr39187.cpp -o pr39187-g.ll -mllvm -opt-bisect-limit=10
+
+; // pr39187.cpp
+; int main() {
+; volatile int foo = 0;
+;
+; int beards = 0;
+; bool cond = foo == 4;
+; int bar = 0;
+; if (cond)
+; beards = 8;
+; else
+; beards = 4;
+;
+; volatile bool face = cond;
+;
+; return face ? beards : 0;
+; }
+
+; CHECK-LABEL: entry
+; CHECK: %foo = alloca i32, align 4
+; CHECK: %face = alloca i8, align 1
+; CHECK: %foo.0..sroa_cast = bitcast i32* %foo to i8*
+; CHECK: store volatile i32 0, i32* %foo, align 4
+; CHECK: %foo.0. = load volatile i32, i32* %foo, align 4, !dbg !16
+; CHECK: %cmp = icmp eq i32 %foo.0., 4, !dbg !16
+; CHECK: %frombool = zext i1 %cmp to i8, !dbg !16
+; CHECK: call void @llvm.dbg.value(metadata i8 %frombool, metadata !13, metadata !DIExpression()), !dbg !16
+; CHECK: call void @llvm.dbg.value(metadata i32 0, metadata !15, metadata !DIExpression()), !dbg !17
+; CHECK: %. = select i1 %cmp, i32 8, i32 4, !dbg !16
+
+; ModuleID = 'pr39187.cpp'
+source_filename = "pr39187.cpp"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux-gnu"
+
+; Function Attrs: norecurse nounwind uwtable
+define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
+entry:
+ %foo = alloca i32, align 4
+ %face = alloca i8, align 1
+ %foo.0..sroa_cast = bitcast i32* %foo to i8*
+ store volatile i32 0, i32* %foo, align 4
+ %foo.0. = load volatile i32, i32* %foo, align 4, !dbg !26
+ %cmp = icmp eq i32 %foo.0., 4, !dbg !26
+ %frombool = zext i1 %cmp to i8, !dbg !26
+ call void @llvm.dbg.value(metadata i8 %frombool, metadata !15, metadata !DIExpression()), !dbg !26
+ call void @llvm.dbg.value(metadata i32 0, metadata !17, metadata !DIExpression()), !dbg !27
+ br i1 %cmp, label %if.then, label %if.else
+
+if.then: ; preds = %entry
+ call void @llvm.dbg.value(metadata i32 8, metadata !14, metadata !DIExpression()), !dbg !25
+ br label %if.end
+
+if.else: ; preds = %entry
+ call void @llvm.dbg.value(metadata i32 4, metadata !14, metadata !DIExpression()), !dbg !25
+ br label %if.end
+
+if.end: ; preds = %if.else, %if.then
+ %beards.0 = phi i32 [ 8, %if.then ], [ 4, %if.else ]
+ store volatile i8 %frombool, i8* %face, align 1
+ %face.0. = load volatile i8, i8* %face, align 1
+ %0 = and i8 %face.0., 1
+ %tobool3 = icmp eq i8 %0, 0
+ %cond4 = select i1 %tobool3, i32 0, i32 %beards.0
+ ret i32 %cond4
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 346301)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "pr39187.cpp", directory: ".")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 8.0.0 (trunk 346301)"}
+!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!14, !15, !17}
+!14 = !DILocalVariable(name: "beards", scope: !7, file: !1, line: 4, type: !10)
+!15 = !DILocalVariable(name: "cond", scope: !7, file: !1, line: 5, type: !16)
+!16 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!17 = !DILocalVariable(name: "bar", scope: !7, file: !1, line: 6, type: !10)
+!25 = !DILocation(line: 4, scope: !7)
+!26 = !DILocation(line: 5, scope: !7)
+!27 = !DILocation(line: 6, scope: !7)