Index: lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -309,6 +309,8 @@
   // Local expression tree should go after the BLOCK.
   for (auto I = Header->getFirstTerminator(), E = Header->begin(); I != E;
        --I) {
+    if (std::prev(I)->isDebugInstr() || std::prev(I)->isPosition())
+      continue;
     if (WebAssembly::isChild(*std::prev(I), MFI))
       AfterSet.insert(&*std::prev(I));
     else
@@ -531,6 +533,8 @@
   // Local expression tree should go after the TRY.
   for (auto I = Header->getFirstTerminator(), E = Header->begin(); I != E;
        --I) {
+    if (std::prev(I)->isDebugInstr() || std::prev(I)->isPosition())
+      continue;
     if (WebAssembly::isChild(*std::prev(I), MFI))
       AfterSet.insert(&*std::prev(I));
     else
Index: test/CodeGen/WebAssembly/cfg-stackify-dbg-skip.mir
===================================================================
--- /dev/null
+++ test/CodeGen/WebAssembly/cfg-stackify-dbg-skip.mir
@@ -0,0 +1,255 @@
+# RUN: llc -mtriple=wasm32-unknown-unknown -run-pass wasm-cfg-stackify %s -o - | FileCheck %s
+
+
+# The test checks if "block" instruction was not inserted inside group of
+# of instructions that form a logical expression. In this case, the test
+# instructions contain DBG_VALUE between them.
+
+--- |
+  ; ModuleID = 'test/CodeGen/WebAssembly/cfg-stackify-dbg-skip.ll'
+  source_filename = "foo.3a1fbbbh-cgu.0"
+  target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+  target triple = "wasm32-unknown-unknown"
+  
+  ; Function Attrs: nounwind
+  define {}* @foo({ i8*, i32 }* nocapture, i32, i64) local_unnamed_addr #0 {
+  start:
+    %tmp.sroa.0.0.extract.trunc.i.i.i.i.i = trunc i64 %2 to i32
+    call void @llvm.dbg.value(metadata i32 %tmp.sroa.0.0.extract.trunc.i.i.i.i.i, metadata !34, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)), !dbg !48
+    %.sroa_cast1.i.i = bitcast { i8*, i32 }* %0 to i32*, !dbg !105
+    store i32 0, i32* %.sroa_cast1.i.i, align 4
+    %3 = icmp eq i32 %tmp.sroa.0.0.extract.trunc.i.i.i.i.i, 0
+    br i1 %3, label %bb9, label %bb2
+  
+  bb2:                                              ; preds = %start
+    %tmp.sroa.4.0.extract.shift.i.i.i.i.i = lshr i64 %2, 32
+    %tmp.sroa.4.0.extract.trunc.i.i.i.i.i = trunc i64 %tmp.sroa.4.0.extract.shift.i.i.i.i.i to i32
+    %4 = tail call i8* @malloc(i32 8)
+    %5 = getelementptr inbounds i8, i8* %4, i32 4
+    %6 = bitcast i8* %5 to i32*
+    store i32 %tmp.sroa.4.0.extract.trunc.i.i.i.i.i, i32* %6, align 4
+    %7 = bitcast i8* %4 to {}*
+    br label %bb9
+  
+  bb9:                                              ; preds = %bb2, %start
+    %data.sroa.0.0 = phi {}* [ %7, %bb2 ], [ inttoptr (i32 1 to {}*), %start ]
+    ret {}* %data.sroa.0.0
+  }
+  
+  ; Function Attrs: nounwind
+  declare noalias i8* @malloc(i32) unnamed_addr #0
+  
+  ; Function Attrs: nounwind readnone speculatable
+  declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+  
+  ; Function Attrs: nounwind
+  declare void @llvm.stackprotector(i8*, i8**) #0
+  
+  attributes #0 = { nounwind }
+  attributes #1 = { nounwind readnone speculatable }
+  
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!33}
+  
+  !0 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !1, producer: "clang LLVM (rustc version 1.30.0-dev)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3)
+  !1 = !DIFile(filename: "foo.rs", directory: "/misc/coresimd")
+  !2 = !{}
+  !3 = !{!4, !29, !31}
+  !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression())
+  !5 = distinct !DIGlobalVariable(name: "vtable", scope: null, file: !6, type: !7, isLocal: true, isDefinition: true)
+  !6 = !DIFile(filename: "<unknown>", directory: "")
+  !7 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "vtable", file: !6, align: 32, flags: DIFlagArtificial, elements: !2, vtableHolder: !8, identifier: "vtable")
+  !8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "PanicPayload<&str>", scope: !9, file: !6, size: 64, align: 32, elements: !12, identifier: "f20029ab88f79681a6fb4031dc880864")
+  !9 = !DINamespace(name: "begin_panic", scope: !10)
+  !10 = !DINamespace(name: "panicking", scope: !11)
+  !11 = !DINamespace(name: "std", scope: null)
+  !12 = !{!13}
+  !13 = !DIDerivedType(tag: DW_TAG_member, name: "inner", scope: !8, file: !6, baseType: !14, size: 64, align: 32)
+  !14 = distinct !DICompositeType(tag: DW_TAG_union_type, name: "Option<&str>", scope: !15, file: !6, size: 64, align: 32, elements: !17, identifier: "fa309c24fa29eafa7eabc3e820fdb228")
+  !15 = !DINamespace(name: "option", scope: !16)
+  !16 = !DINamespace(name: "core", scope: null)
+  !17 = !{!18}
+  !18 = !DIDerivedType(tag: DW_TAG_member, name: "RUST$ENCODED$ENUM$0$None", scope: !14, file: !6, baseType: !19, size: 64, align: 32)
+  !19 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Some", scope: !15, file: !6, size: 64, align: 32, elements: !20, identifier: "fa309c24fa29eafa7eabc3e820fdb228::Some")
+  !20 = !{!21}
+  !21 = !DIDerivedType(tag: DW_TAG_member, name: "__0", scope: !19, file: !6, baseType: !22, size: 64, align: 32)
+  !22 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "&str", file: !6, size: 64, align: 32, elements: !23, identifier: "111094d970b097647de579f9c509ef08")
+  !23 = !{!24, !27}
+  !24 = !DIDerivedType(tag: DW_TAG_member, name: "data_ptr", scope: !22, file: !6, baseType: !25, size: 32, align: 32)
+  !25 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const u8", baseType: !26, size: 32, align: 32)
+  !26 = !DIBasicType(name: "u8", size: 8, encoding: DW_ATE_unsigned)
+  !27 = !DIDerivedType(tag: DW_TAG_member, name: "length", scope: !22, file: !6, baseType: !28, size: 32, align: 32, offset: 32)
+  !28 = !DIBasicType(name: "usize", size: 32, encoding: DW_ATE_unsigned)
+  !29 = !DIGlobalVariableExpression(var: !30, expr: !DIExpression())
+  !30 = distinct !DIGlobalVariable(name: "vtable", scope: null, file: !6, type: !7, isLocal: true, isDefinition: true)
+  !31 = !DIGlobalVariableExpression(var: !32, expr: !DIExpression())
+  !32 = distinct !DIGlobalVariable(name: "vtable", scope: null, file: !6, type: !7, isLocal: true, isDefinition: true)
+  !33 = !{i32 2, !"Debug Info Version", i32 3}
+  !34 = !DILocalVariable(name: "z", scope: !35, file: !36, line: 357, type: !14, align: 4)
+  !35 = distinct !DILexicalBlock(scope: !37, file: !36, line: 357, column: 8)
+  !36 = !DIFile(filename: "/misc/libcore/ptr.rs", directory: "")
+  !37 = distinct !DISubprogram(name: "swap_nonoverlapping_one<core::option::Option<&str>>", linkageName: "_ZN4core3ptr23swap_nonoverlapping_one17h9b13106d1b81ade4E", scope: !38, file: !36, line: 353, type: !39, isLocal: true, isDefinition: true, scopeLine: 353, flags: DIFlagPrototyped, isOptimized: true, unit: !0, templateParams: !46, retainedNodes: !42)
+  !38 = !DINamespace(name: "ptr", scope: !16)
+  !39 = !DISubroutineType(types: !40)
+  !40 = !{null, !41, !41}
+  !41 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*mut core::option::Option<&str>", baseType: !14, size: 32, align: 32)
+  !42 = !{!43, !45, !34}
+  !43 = !DILocalVariable(name: "x", arg: 1, scope: !37, file: !44, line: 1, type: !41)
+  !44 = !DIFile(filename: "foo.rs", directory: "")
+  !45 = !DILocalVariable(name: "y", arg: 2, scope: !37, file: !44, line: 1, type: !41)
+  !46 = !{!47}
+  !47 = !DITemplateTypeParameter(name: "T", type: !14)
+  !48 = !DILocation(line: 357, column: 12, scope: !35, inlinedAt: !49)
+  !49 = distinct !DILocation(line: 637, column: 8, scope: !50, inlinedAt: !60)
+  !50 = distinct !DILexicalBlock(scope: !52, file: !51, line: 636, column: 4)
+  !51 = !DIFile(filename: "/misc/libcore/mem.rs", directory: "")
+  !52 = distinct !DISubprogram(name: "swap<core::option::Option<&str>>", linkageName: "_ZN4core3mem4swap17hf525fca8ad6e588dE", scope: !53, file: !51, line: 635, type: !54, isLocal: true, isDefinition: true, scopeLine: 635, flags: DIFlagPrototyped, isOptimized: true, unit: !0, templateParams: !46, retainedNodes: !57)
+  !53 = !DINamespace(name: "mem", scope: !16)
+  !54 = !DISubroutineType(types: !55)
+  !55 = !{null, !56, !56}
+  !56 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&mut core::option::Option<&str>", baseType: !14, size: 32, align: 32)
+  !57 = !{!58, !59}
+  !58 = !DILocalVariable(name: "x", arg: 1, scope: !52, file: !44, line: 1, type: !56)
+  !59 = !DILocalVariable(name: "y", arg: 2, scope: !52, file: !44, line: 1, type: !56)
+  !60 = distinct !DILocation(line: 695, column: 4, scope: !61, inlinedAt: !67)
+  !61 = distinct !DISubprogram(name: "replace<core::option::Option<&str>>", linkageName: "_ZN4core3mem7replace17he6f7041b81a6d845E", scope: !53, file: !51, line: 694, type: !62, isLocal: true, isDefinition: true, scopeLine: 694, flags: DIFlagPrototyped, isOptimized: true, unit: !0, templateParams: !46, retainedNodes: !64)
+  !62 = !DISubroutineType(types: !63)
+  !63 = !{!14, !56, !14}
+  !64 = !{!65, !66}
+  !65 = !DILocalVariable(name: "dest", arg: 1, scope: !61, file: !44, line: 1, type: !56)
+  !66 = !DILocalVariable(name: "src", arg: 2, scope: !61, file: !44, line: 1, type: !14)
+  !67 = distinct !DILocation(line: 858, column: 8, scope: !68, inlinedAt: !76)
+  !68 = distinct !DISubprogram(name: "take<&str>", linkageName: "_ZN38_$LT$core..option..Option$LT$T$GT$$GT$4take17ha569a64f962bb285E", scope: !14, file: !69, line: 857, type: !70, isLocal: true, isDefinition: true, scopeLine: 857, flags: DIFlagPrototyped, isOptimized: true, unit: !0, templateParams: !74, retainedNodes: !72)
+  !69 = !DIFile(filename: "/misc/libcore/option.rs", directory: "")
+  !70 = !DISubroutineType(types: !71)
+  !71 = !{!14, !56}
+  !72 = !{!73}
+  !73 = !DILocalVariable(name: "self", arg: 1, scope: !68, file: !44, line: 1, type: !56)
+  !74 = !{!75}
+  !75 = !DITemplateTypeParameter(name: "T", type: !22)
+  !76 = distinct !DILocation(line: 425, column: 29, scope: !77)
+  !77 = distinct !DISubprogram(name: "box_me_up<&str>", linkageName: "_ZN91_$LT$std..panicking..begin_panic..PanicPayload$LT$A$GT$$u20$as$u20$core..panic..BoxMeUp$GT$9box_me_up17h0db1ddc6159c8fb6E", scope: !79, file: !78, line: 424, type: !80, isLocal: true, isDefinition: true, scopeLine: 424, flags: DIFlagPrototyped, isOptimized: true, unit: !0, templateParams: !103, retainedNodes: !93)
+  !78 = !DIFile(filename: "/misc/libstd/panicking.rs", directory: "")
+  !79 = !DINamespace(name: "{{impl}}", scope: !9)
+  !80 = !DISubroutineType(types: !81)
+  !81 = !{!82, !92}
+  !82 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "*mut Any", scope: !83, file: !6, size: 64, align: 32, elements: !84, identifier: "53372fa6cb48d0d4ed09ef2b1dc9567c")
+  !83 = !DINamespace(name: "any", scope: !16)
+  !84 = !{!85, !87}
+  !85 = !DIDerivedType(tag: DW_TAG_member, name: "pointer", scope: !82, file: !6, baseType: !86, size: 32, align: 32, flags: DIFlagArtificial)
+  !86 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*mut u8", baseType: !26, size: 32, align: 32)
+  !87 = !DIDerivedType(tag: DW_TAG_member, name: "vtable", scope: !82, file: !6, baseType: !88, size: 32, align: 32, offset: 32, flags: DIFlagArtificial)
+  !88 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&[usize; 3]", baseType: !89, size: 32, align: 32)
+  !89 = !DICompositeType(tag: DW_TAG_array_type, baseType: !28, size: 96, align: 32, elements: !90)
+  !90 = !{!91}
+  !91 = !DISubrange(count: 3)
+  !92 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "&mut std::panicking::begin_panic::PanicPayload<&str>", baseType: !8, size: 32, align: 32)
+  !93 = !{!94, !95, !101}
+  !94 = !DILocalVariable(name: "self", arg: 1, scope: !77, file: !44, line: 1, type: !92)
+  !95 = !DILocalVariable(name: "data", scope: !96, file: !78, line: 425, type: !97, align: 4)
+  !96 = distinct !DILexicalBlock(scope: !77, file: !78, line: 425, column: 12)
+  !97 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "Box<Any>", scope: !83, file: !6, size: 64, align: 32, elements: !98, identifier: "9e5777c3b641846cf0b3f45ae396cc20")
+  !98 = !{!99, !100}
+  !99 = !DIDerivedType(tag: DW_TAG_member, name: "pointer", scope: !97, file: !6, baseType: !86, size: 32, align: 32, flags: DIFlagArtificial)
+  !100 = !DIDerivedType(tag: DW_TAG_member, name: "vtable", scope: !97, file: !6, baseType: !88, size: 32, align: 32, offset: 32, flags: DIFlagArtificial)
+  !101 = !DILocalVariable(name: "a", scope: !102, file: !78, line: 426, type: !22, align: 4)
+  !102 = distinct !DILexicalBlock(scope: !77, file: !78, line: 426, column: 27)
+  !103 = !{!104}
+  !104 = !DITemplateTypeParameter(name: "A", type: !22)
+  !105 = !DILocation(line: 358, column: 8, scope: !35, inlinedAt: !49)
+
+...
+---
+name:            foo
+alignment:       0
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: false
+registers:       
+  - { id: 0, class: i32, preferred-register: '' }
+  - { id: 1, class: i32, preferred-register: '' }
+  - { id: 2, class: i64, preferred-register: '' }
+  - { id: 3, class: i32, preferred-register: '' }
+  - { id: 4, class: i32, preferred-register: '' }
+  - { id: 5, class: i32, preferred-register: '' }
+  - { id: 6, class: i32, preferred-register: '' }
+  - { id: 7, class: i64, preferred-register: '' }
+  - { id: 8, class: i64, preferred-register: '' }
+  - { id: 9, class: i32, preferred-register: '' }
+  - { id: 10, class: i32, preferred-register: '' }
+  - { id: 11, class: i32, preferred-register: '' }
+  - { id: 12, class: i32, preferred-register: '' }
+  - { id: 13, class: i64, preferred-register: '' }
+  - { id: 14, class: i64, preferred-register: '' }
+  - { id: 15, class: i32, preferred-register: '' }
+  - { id: 16, class: i32, preferred-register: '' }
+  - { id: 17, class: i32, preferred-register: '' }
+  - { id: 18, class: i32, preferred-register: '' }
+  - { id: 19, class: i32, preferred-register: '' }
+  - { id: 20, class: i32, preferred-register: '' }
+  - { id: 21, class: i32, preferred-register: '' }
+  - { id: 22, class: i64, preferred-register: '' }
+  - { id: 23, class: i64, preferred-register: '' }
+  - { id: 24, class: i32, preferred-register: '' }
+liveins:         
+  - { reg: '$arguments', virtual-reg: '' }
+  - { reg: '$value_stack', virtual-reg: '' }
+frameInfo:       
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    0
+  adjustsStack:    false
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      
+stack:           
+constants:       
+body:             |
+  bb.0.start:
+    successors: %bb.2(0x30000000), %bb.1(0x50000000)
+  
+    %21:i32 = GET_LOCAL_I32 0, implicit-def $arguments
+    %11:i32 = CONST_I32 0, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    STORE_I32 2, 0, %21, %11, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack :: (store 4 into %ir..sroa_cast1.i.i)
+    %22:i64 = GET_LOCAL_I64 2, implicit-def $arguments
+    %18:i32 = I32_WRAP_I64 %22, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    DBG_VALUE debug-use %18, debug-use $noreg, !34, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !48
+    BR_UNLESS %bb.2, %18, implicit-def $arguments, implicit-def $value_stack, implicit $value_stack
+  
+  bb.1.bb2:
+    %15:i32 = CONST_I32 8, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    %20:i32 = CALL_I32 @malloc, %15, implicit-def dead $arguments, implicit $sp32, implicit $sp64, implicit-def $value_stack, implicit $value_stack
+    %19:i32 = TEE_LOCAL_I32 0, %20, implicit-def $arguments
+    %23:i64 = GET_LOCAL_I64 2, implicit-def $arguments
+    %13:i64 = CONST_I64 32, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    %14:i64 = SHR_U_I64 %23, %13, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    STORE32_I64 2, 4, %19, %14, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack :: (store 4 into %ir.6)
+    %24:i32 = GET_LOCAL_I32 0, implicit-def $arguments
+    RETURN_I32 %24, implicit-def dead $arguments
+  
+  bb.2:
+    %17:i32 = CONST_I32 1, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+    RETURN_I32 %17, implicit-def dead $arguments, implicit-def $value_stack, implicit $value_stack
+
+  ; CHECK: body:
+  ; CHECK: GET_LOCAL_I64
+  ; CHECK-NEXT: I32_WRAP_I64
+  ; CHECK-NEXT: DBG_VALUE
+  ; CHECK-NEXT: BLOCK
+  ; CHECK-NEXT: BR_UNLESS
+...