[Debuginfo][SROA] Need to handle dbg.value in SROA pass.

SROA pass processes debug info incorrecly if applied twice.
Specifically, after SROA works first time, instcombine converts dbg.declare
intrinsics into dbg.value. Inlining creates new opportunities for SROA,
so it is called again. This time it does not handle correctly previously
inserted dbg.value intrinsics.

Differential Revision: https://reviews.llvm.org/D64595

llvm-svn: 370906

llvm/lib/Transforms/Utils/Local.cpp

@@ -1378,7 +1378,12 @@ void llvm::ConvertDebugDeclareToDebugValue(DbgVariableIntrinsic *DII,
 /// Determine whether this alloca is either a VLA or an array.
 static bool isArray(AllocaInst *AI) {
   return AI->isArrayAllocation() ||
-    AI->getType()->getElementType()->isArrayTy();
+         (AI->getAllocatedType() && AI->getAllocatedType()->isArrayTy());
+}
+
+/// Determine whether this alloca is a structure.
+static bool isStructure(AllocaInst *AI) {
+  return AI->getAllocatedType() && AI->getAllocatedType()->isStructTy();
 }
 
 /// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
@@ -1403,7 +1408,7 @@ bool llvm::LowerDbgDeclare(Function &F) {
     // stored on the stack, while the dbg.declare can only describe
     // the stack slot (and at a lexical-scope granularity). Later
     // passes will attempt to elide the stack slot.
-    if (!AI || isArray(AI))
+    if (!AI || isArray(AI) || isStructure(AI))
       continue;
 
     // A volatile load/store means that the alloca can't be elided anyway.

llvm/test/DebugInfo/X86/sroa-after-inlining.ll

@@ -0,0 +1,139 @@
+; RUN: opt %s -sroa -instcombine -inline -instcombine -sroa -verify -S -o - | FileCheck %s
+;
+; This test checks that SROA pass processes debug info correctly if applied twice.
+; Specifically, after SROA works first time, instcombine converts dbg.declare
+; intrinsics into dbg.value. Inlining creates new opportunities for SROA,
+; so it is called again. This time it does not handle correctly previously
+; inserted dbg.value intrinsics: current SROA implementation while doing
+; "Migrate debug information from the old alloca to the new alloca(s)" handles
+; only dbg.declare intrinsic. In this case, original dbg.declare was lowered by
+; instcombine pass into dbg.value. When it comes into SROA second time, all dbg.value
+; intrinsics, inserted by instcombine pass before second SROA, just not updated
+; (though SROA was done). The fix is to not lower dbg.declare for structures.
+
+;
+; Hand-reduced from this example (-g -O -mllvm -disable-llvm-optzns -gno-column-info):
+;
+; struct S1 {
+;     int p1;
+;
+;     bool IsNull (  ) { return p1 == 0; }
+; };
+;
+; S1 foo ( void );
+;
+; int bar (  ) {
+;     S1 result = foo();
+;
+;     if (result.IsNull())
+;         return 0;
+;
+;     return result.p1 + 1;
+; }
+
+; CHECK: _Z3barv
+; CHECK: %[[RESULT:.*]] = call i32 @_Z3foov
+; CHECK: llvm.dbg.value(metadata i32 %[[RESULT]], metadata [[METADATA_IDX1:![0-9]+]]
+; CHECK: ret
+; CHECK: DICompileUnit
+; CHECK: [[METADATA_IDX1]] = !DILocalVariable(name: "result"
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.S1 = type { i32 }
+
+$_ZN2S16IsNullEv = comdat any
+
+define dso_local i32 @_Z3barv() !dbg !7 {
+entry:
+  %retval = alloca i32, align 4
+  %result = alloca %struct.S1, align 4
+  %cleanup.dest.slot = alloca i32, align 4
+  %0 = bitcast %struct.S1* %result to i8*, !dbg !21
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %0) #5, !dbg !21
+  call void @llvm.dbg.declare(metadata %struct.S1* %result, metadata !12, metadata !DIExpression()), !dbg !21
+  %call = call i32 @_Z3foov(), !dbg !21
+  %coerce.dive = getelementptr inbounds %struct.S1, %struct.S1* %result, i32 0, i32 0, !dbg !21
+  store i32 %call, i32* %coerce.dive, align 4, !dbg !21
+  %call1 = call zeroext i1 @_ZN2S16IsNullEv(%struct.S1* %result), !dbg !22
+  br i1 %call1, label %if.then, label %if.end, !dbg !24
+
+if.then:                                          ; preds = %entry
+  store i32 0, i32* %retval, align 4, !dbg !25
+  store i32 1, i32* %cleanup.dest.slot, align 4
+  br label %cleanup, !dbg !25
+
+if.end:                                           ; preds = %entry
+  %p1 = getelementptr inbounds %struct.S1, %struct.S1* %result, i32 0, i32 0, !dbg !26
+  %1 = load i32, i32* %p1, align 4, !dbg !26
+  %add = add nsw i32 %1, 1, !dbg !26
+  store i32 %add, i32* %retval, align 4, !dbg !26
+  store i32 1, i32* %cleanup.dest.slot, align 4
+  br label %cleanup, !dbg !26
+
+cleanup:                                          ; preds = %if.end, %if.then
+  %2 = bitcast %struct.S1* %result to i8*, !dbg !32
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %2) #5, !dbg !32
+  %3 = load i32, i32* %retval, align 4, !dbg !32
+  ret i32 %3, !dbg !32
+}
+
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+declare dso_local i32 @_Z3foov()
+
+define linkonce_odr dso_local zeroext i1 @_ZN2S16IsNullEv(%struct.S1* %this) #4 comdat align 2 !dbg !33 {
+entry:
+  %this.addr = alloca %struct.S1*, align 8
+  store %struct.S1* %this, %struct.S1** %this.addr, align 8
+  call void @llvm.dbg.declare(metadata %struct.S1** %this.addr, metadata !35, metadata !DIExpression()), !dbg !39
+  %this1 = load %struct.S1*, %struct.S1** %this.addr, align 8
+  %p1 = getelementptr inbounds %struct.S1, %struct.S1* %this1, i32 0, i32 0, !dbg !40
+  %0 = load i32, i32* %p1, align 4, !dbg !40
+  %cmp = icmp eq i32 %0, 0, !dbg !40
+  ret i1 %cmp, !dbg !40
+}
+
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture)
+
+!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", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "sroa-after-inlining.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"}
+!7 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !1, file: !1, line: 9, type: !8, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!12}
+!12 = !DILocalVariable(name: "result", scope: !7, file: !1, line: 10, type: !13)
+!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "S1", file: !1, line: 1, size: 32, flags: DIFlagTypePassByValue, elements: !14, identifier: "_ZTS2S1")
+!14 = !{!15, !16}
+!15 = !DIDerivedType(tag: DW_TAG_member, name: "p1", scope: !13, file: !1, line: 2, baseType: !10, size: 32)
+!16 = !DISubprogram(name: "IsNull", linkageName: "_ZN2S16IsNullEv", scope: !13, file: !1, line: 4, type: !17, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!17 = !DISubroutineType(types: !18)
+!18 = !{!19, !20}
+!19 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!20 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64, flags: DIFlagArtificial | DIFlagObjectPointer)
+!21 = !DILocation(line: 10, scope: !7)
+!22 = !DILocation(line: 12, scope: !23)
+!23 = distinct !DILexicalBlock(scope: !7, file: !1, line: 12)
+!24 = !DILocation(line: 12, scope: !7)
+!25 = !DILocation(line: 13, scope: !23)
+!26 = !DILocation(line: 15, scope: !7)
+!32 = !DILocation(line: 16, scope: !7)
+!33 = distinct !DISubprogram(name: "IsNull", linkageName: "_ZN2S16IsNullEv", scope: !13, file: !1, line: 4, type: !17, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !16, retainedNodes: !34)
+!34 = !{!35}
+!35 = !DILocalVariable(name: "this", arg: 1, scope: !33, type: !36, flags: DIFlagArtificial | DIFlagObjectPointer)
+!36 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64)
+!39 = !DILocation(line: 0, scope: !33)
+!40 = !DILocation(line: 4, scope: !33)