Debug Info: remove duplication of DIEs when a DIE can be shared across CUs.

We add a map in DwarfDebug to map MDNodes that are shareable across CUs to the
corresponding DIEs: MDTypeNodeToDieMap. These DIEs can be shared across CUs,
that is why we keep the maps in DwarfDebug instead of CompileUnit.

We make the assumption that if a DIE is not added to an owner yet, we assume
it belongs to the current CU. Since DIEs for the type system are added to
their owners immediately after creation, and other DIEs belong to the current
CU, the assumption should be true.

A testing case is added to show that we only create a single DIE for a type
MDNode and we use ref_addr to refer to the type DIE.

We also add a testing case to show ref_addr relocations for non-darwin
platforms.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193779 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/DIE.cpp b/lib/CodeGen/AsmPrinter/DIE.cpp
index 334c10831612cfe55dc6d87fb987b8488e36aa05..69444285f4ec4691429c388174260f784187f557 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -115,13 +115,21 @@ DIE::~DIE() {
 /// Climb up the parent chain to get the compile unit DIE to which this DIE
 /// belongs.
 const DIE *DIE::getCompileUnit() const {
+  const DIE *Cu = getCompileUnitOrNull();
+  assert(Cu && "We should not have orphaned DIEs.");
+  return Cu;
+}
+
+/// Climb up the parent chain to get the compile unit DIE this DIE belongs
+/// to. Return NULL if DIE is not added to an owner yet.
+const DIE *DIE::getCompileUnitOrNull() const {
   const DIE *p = this;
   while (p) {
     if (p->getTag() == dwarf::DW_TAG_compile_unit)
       return p;
     p = p->getParent();
   }
-  llvm_unreachable("We should not have orphaned DIEs.");
+  return NULL;
 }
 
 DIEValue *DIE::findAttribute(uint16_t Attribute) {

diff --git a/lib/CodeGen/AsmPrinter/DIE.h b/lib/CodeGen/AsmPrinter/DIE.h
index 96a01327f769ff2407ee96ca2e99190a7fa44bc8..f4fa326ef67a49968a58efe553b833b8a14d9c6a 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DIE.h
+++ b/lib/CodeGen/AsmPrinter/DIE.h
@@ -149,6 +149,9 @@ namespace llvm {
     /// Climb up the parent chain to get the compile unit DIE this DIE belongs
     /// to.
     const DIE *getCompileUnit() const;
+    /// Similar to getCompileUnit, returns null when DIE is not added to an
+    /// owner yet.
+    const DIE *getCompileUnitOrNull() const;
     void setOffset(unsigned O) { Offset = O; }
     void setSize(unsigned S) { Size = S; }
 

diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 703e2c12d8d26196248ca109ef944dc8dbe03d90..575cf31eaa6a56fe4ac2f177ef7767b5ac9c87b9 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -98,6 +98,35 @@ int64_t CompileUnit::getDefaultLowerBound() const {
   return -1;
 }
 
+/// Check whether the DIE for this MDNode can be shared across CUs.
+static bool isShareableAcrossCUs(const MDNode *N) {
+  // When the MDNode can be part of the type system, the DIE can be
+  // shared across CUs.
+  return DIDescriptor(N).isType() ||
+         (DIDescriptor(N).isSubprogram() && !DISubprogram(N).isDefinition());
+}
+
+/// getDIE - Returns the debug information entry map slot for the
+/// specified debug variable. We delegate the request to DwarfDebug
+/// when the DIE for this MDNode can be shared across CUs. The mappings
+/// will be kept in DwarfDebug for shareable DIEs.
+DIE *CompileUnit::getDIE(const MDNode *N) const {
+  if (isShareableAcrossCUs(N))
+    return DD->getDIE(N);
+  return MDNodeToDieMap.lookup(N);
+}
+
+/// insertDIE - Insert DIE into the map. We delegate the request to DwarfDebug
+/// when the DIE for this MDNode can be shared across CUs. The mappings
+/// will be kept in DwarfDebug for shareable DIEs.
+void CompileUnit::insertDIE(const MDNode *N, DIE *D) {
+  if (isShareableAcrossCUs(N)) {
+    DD->insertDIE(N, D);
+    return;
+  }
+  MDNodeToDieMap.insert(std::make_pair(N, D));
+}
+
 /// addFlag - Add a flag that is true.
 void CompileUnit::addFlag(DIE *Die, dwarf::Attribute Attribute) {
   if (DD->getDwarfVersion() >= 4)
@@ -245,8 +274,21 @@ void CompileUnit::addDelta(DIE *Die, dwarf::Attribute Attribute, dwarf::Form For
 /// addDIEEntry - Add a DIE attribute data and value.
 ///
 void CompileUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry) {
-  // We currently only use ref4.
-  Die->addValue(Attribute, dwarf::DW_FORM_ref4, createDIEEntry(Entry));
+  addDIEEntry(Die, Attribute, createDIEEntry(Entry));
+}
+
+void CompileUnit::addDIEEntry(DIE *Die, dwarf::Attribute Attribute,
+                              DIEEntry *Entry) {
+  const DIE *DieCU = Die->getCompileUnitOrNull();
+  const DIE *EntryCU = Entry->getEntry()->getCompileUnitOrNull();
+  if (!DieCU)
+    // We assume that Die belongs to this CU, if it is not linked to any CU yet.
+    DieCU = getCUDie();
+  if (!EntryCU)
+    EntryCU = getCUDie();
+  Die->addValue(Attribute, EntryCU == DieCU ? dwarf::DW_FORM_ref4
+                                            : dwarf::DW_FORM_ref_addr,
+                Entry);
 }
 
 /// Create a DIE with the given Tag, add the DIE to its parent, and
@@ -882,7 +924,7 @@ void CompileUnit::addType(DIE *Entity, DIType Ty, dwarf::Attribute Attribute) {
   DIEEntry *Entry = getDIEEntry(Ty);
   // If it exists then use the existing value.
   if (Entry) {
-    Entity->addValue(Attribute, dwarf::DW_FORM_ref4, Entry);
+    addDIEEntry(Entity, Attribute, Entry);
     return;
   }
 
@@ -892,7 +934,7 @@ void CompileUnit::addType(DIE *Entity, DIType Ty, dwarf::Attribute Attribute) {
   // Set up proxy.
   Entry = createDIEEntry(Buffer);
   insertDIEEntry(Ty, Entry);
-  Entity->addValue(Attribute, dwarf::DW_FORM_ref4, Entry);
+  addDIEEntry(Entity, Attribute, Entry);
 
   // If this is a complete composite type then include it in the
   // list of global types.

diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 8e2d69de727dd5f27a6b7a6ec2799bdeb2225c36..a177d1910ba6c8cfecdbf930871ef8e7afa73d71 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -155,15 +155,19 @@ public:
   void addAccelType(StringRef Name, std::pair<DIE *, unsigned> Die);
 
   /// getDIE - Returns the debug information entry map slot for the
-  /// specified debug variable.
-  DIE *getDIE(const MDNode *N) const { return MDNodeToDieMap.lookup(N); }
+  /// specified debug variable. We delegate the request to DwarfDebug
+  /// when the MDNode can be part of the type system, since DIEs for
+  /// the type system can be shared across CUs and the mappings are
+  /// kept in DwarfDebug.
+  DIE *getDIE(const MDNode *N) const;
 
   DIEBlock *getDIEBlock() { return new (DIEValueAllocator) DIEBlock(); }
 
-  /// insertDIE - Insert DIE into the map.
-  void insertDIE(const MDNode *N, DIE *D) {
-    MDNodeToDieMap.insert(std::make_pair(N, D));
-  }
+  /// insertDIE - Insert DIE into the map. We delegate the request to DwarfDebug
+  /// when the MDNode can be part of the type system, since DIEs for
+  /// the type system can be shared across CUs and the mappings are
+  /// kept in DwarfDebug.
+  void insertDIE(const MDNode *N, DIE *D);
 
   /// addDie - Adds or interns the DIE to the compile unit.
   ///
@@ -224,6 +228,10 @@ public:
   ///
   void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIE *Entry);
 
+  /// addDIEEntry - Add a DIE attribute data and value.
+  ///
+  void addDIEEntry(DIE *Die, dwarf::Attribute Attribute, DIEEntry *Entry);
+
   /// addBlock - Add block data.
   ///
   void addBlock(DIE *Die, dwarf::Attribute Attribute, DIEBlock *Block);

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 771cb3215a326c027a6bdc3c8214694bc80b981d..d18b7a55d31e2713e7757ec0afcf6f8e77a6b78a 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2083,6 +2083,9 @@ void DwarfDebug::emitDIE(DIE *Die, ArrayRef<DIEAbbrev *> Abbrevs) {
                                          DwarfInfoSectionSym,
                                          DIEEntry::getRefAddrSize(Asm));
       } else {
+        // Make sure Origin belong to the same CU.
+        assert(Die->getCompileUnit() == Origin->getCompileUnit() &&
+               "The referenced DIE should belong to the same CU in ref4");
         Asm->EmitInt32(Addr);
       }
       break;

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 90ca2763e6b0a75122703c04d3b1751b0aa5b1cd..84fdcdd75e990d6cc5bb562e245971ed17d912f9 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -332,6 +332,11 @@ class DwarfDebug {
   // Maps a CU DIE with its corresponding CompileUnit.
   DenseMap <const DIE *, CompileUnit *> CUDieMap;
 
+  /// Maps MDNodes for type sysstem with the corresponding DIEs. These DIEs can
+  /// be shared across CUs, that is why we keep the map here instead
+  /// of in CompileUnit.
+  DenseMap<const MDNode *, DIE *> MDTypeNodeToDieMap;
+
   // Used to uniquely define abbreviations.
   FoldingSet<DIEAbbrev> AbbreviationsSet;
 
@@ -662,6 +667,13 @@ public:
   //
   DwarfDebug(AsmPrinter *A, Module *M);
 
+  void insertDIE(const MDNode *TypeMD, DIE *Die) {
+    MDTypeNodeToDieMap.insert(std::make_pair(TypeMD, Die));
+  }
+  DIE *getDIE(const MDNode *TypeMD) {
+    return MDTypeNodeToDieMap.lookup(TypeMD);
+  }
+
   /// \brief Emit all Dwarf sections that should come prior to the
   /// content.
   void beginModule();

diff --git a/test/DebugInfo/X86/ref_addr_relocation.ll b/test/DebugInfo/X86/ref_addr_relocation.ll
new file mode 100644 (file)
index 0000000..3c1221f
--- /dev/null
+++ b/test/DebugInfo/X86/ref_addr_relocation.ll
@@ -0,0 +1,70 @@
+; RUN: llc -filetype=asm -O0 -mtriple=x86_64-linux-gnu < %s | FileCheck %s
+; RUN: llc -filetype=obj -O0 %s -mtriple=x86_64-linux-gnu -o %t
+; RUN: llvm-dwarfdump %t | FileCheck %s -check-prefix=CHECK-DWARF
+
+; RUN: llc -filetype=obj %s -mtriple=x86_64-apple-darwin -o %t2
+; RUN: llvm-dwarfdump %t2 | FileCheck %s -check-prefix=DARWIN-DWARF
+
+; Testing case generated from:
+; clang++ tu1.cpp tu2.cpp -g -emit-llvm -c
+; llvm-link tu1.bc tu2.bc -o tu12.ll -S
+; cat hdr.h
+; struct foo {
+; };
+; cat tu1.cpp
+; #include "hdr.h"
+; foo f;
+; cat tu2.cpp
+; #include "hdr.h"
+; foo g;
+
+; Make sure we use relocation for ref_addr on non-darwin platforms.
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_TAG_variable
+; CHECK: .long [[TYPE:.*]] # DW_AT_type
+; CHECK: DW_TAG_structure_type
+; CHECK: debug_info_end0
+; CHECK: DW_TAG_compile_unit
+; CHECK-NOT: DW_TAG_structure_type
+; This variable's type is in the 1st CU.
+; CHECK: DW_TAG_variable
+; Make sure this is relocatable.
+; CHECK: .quad .Lsection_info+[[TYPE]] # DW_AT_type
+; CHECK-NOT: DW_TAG_structure_type
+; CHECK: debug_info_end1
+
+; CHECK-DWARF: DW_TAG_compile_unit
+; CHECK-DWARF: 0x[[ADDR:.*]]: DW_TAG_structure_type
+; CHECK-DWARF: DW_TAG_compile_unit
+; CHECK-DWARF: DW_TAG_variable
+; CHECK-DWARF: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[ADDR]])
+
+; DARWIN-DWARF: DW_TAG_compile_unit
+; DARWIN-DWARF: 0x[[ADDR:.*]]: DW_TAG_structure_type
+; DARWIN-DWARF: DW_TAG_compile_unit
+; DARWIN-DWARF: DW_TAG_variable
+; DARWIN-DWARF: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[ADDR]])
+
+%struct.foo = type { i8 }
+
+@f = global %struct.foo zeroinitializer, align 1
+@g = global %struct.foo zeroinitializer, align 1
+
+!llvm.dbg.cu = !{!0, !9}
+!llvm.module.flags = !{!14}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.4 (trunk 191799)", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !2, metadata !6, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu1.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"tu1.cpp", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786451, metadata !5, null, metadata !"foo", i32 1, i64 8, i64 8, i32 0, i32 0, null, metadata !2, i32 0, null, null, metadata !"_ZTS3foo"} ; [ DW_TAG_structure_type ] [foo] [line 1, size 8, align 8, offset 0] [def] [from ]
+!5 = metadata !{metadata !"./hdr.h", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!6 = metadata !{metadata !7}
+!7 = metadata !{i32 786484, i32 0, null, metadata !"f", metadata !"f", metadata !"", metadata !8, i32 2, metadata !4, i32 0, i32 1, %struct.foo* @f, null} ; [ DW_TAG_variable ] [f] [line 2] [def]
+!8 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu1.cpp]
+!9 = metadata !{i32 786449, metadata !10, i32 4, metadata !"clang version 3.4 (trunk 191799)", i1 false, metadata !"", i32 0, metadata !2, metadata !3, metadata !2, metadata !11, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu2.cpp] [DW_LANG_C_plus_plus]
+!10 = metadata !{metadata !"tu2.cpp", metadata !"/Users/manmanren/test-Nov/type_unique_air/ref_addr"}
+!11 = metadata !{metadata !12}
+!12 = metadata !{i32 786484, i32 0, null, metadata !"g", metadata !"g", metadata !"", metadata !13, i32 2, metadata !4, i32 0, i32 1, %struct.foo* @g, null} ; [ DW_TAG_variable ] [g] [line 2] [def]
+!13 = metadata !{i32 786473, metadata !10}        ; [ DW_TAG_file_type ] [/Users/manmanren/test-Nov/type_unique_air/ref_addr/tu2.cpp]
+!14 = metadata !{i32 2, metadata !"Dwarf Version", i32 2}

diff --git a/test/Linker/Inputs/type-unique-simple2-a.ll b/test/Linker/Inputs/type-unique-simple2-a.ll
index 20cfd5450539640c04f152ee483e8cc974f02489..50581267d5712cf638d985059f9281aa92397763 100644 (file)
--- a/test/Linker/Inputs/type-unique-simple2-a.ll
+++ b/test/Linker/Inputs/type-unique-simple2-a.ll
@@ -1,14 +1,18 @@
-; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
-; CHECK-NEXT: DW_AT_name {{.*}} = "int"
-; CHECK-NOT: DW_TAG_base_type
+; Make sure the backend generates a single DIE and uses ref_addr.
 ; CHECK: 0x[[BASE:.*]]: DW_TAG_structure_type
 ; CHECK-NEXT: DW_AT_name {{.*}} = "Base"
 ; CHECK-NOT: DW_TAG_structure_type
+; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "int"
+; CHECK-NOT: DW_TAG_base_type
+
+; CHECK: DW_TAG_compile_unit
 ; CHECK: DW_TAG_formal_parameter
 ; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[INT]])
 ; CHECK: DW_TAG_variable
 ; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[BASE]])
 
+; Make sure llvm-link only generates a single copy of the struct.
 ; LINK: DW_TAG_structure_type
 ; LINK-NOT: DW_TAG_structure_type
 

diff --git a/test/Linker/type-unique-simple-a.ll b/test/Linker/type-unique-simple-a.ll
index c8f9462d80db477960ca95d11f581e3ac2c4ad9d..808563f2939c329a01bb618d552691696681d010 100644 (file)
--- a/test/Linker/type-unique-simple-a.ll
+++ b/test/Linker/type-unique-simple-a.ll
@@ -1,7 +1,27 @@
-; RUN: llvm-link %s %p/type-unique-simple-b.ll -S -o - | FileCheck %s
+; REQUIRES: object-emission
 
-; CHECK: DW_TAG_structure_type
+; RUN: llvm-link %s %p/type-unique-simple-b.ll -S -o %t
+; RUN: cat %t | FileCheck %s -check-prefix=LINK
+; RUN: llc -filetype=obj -O0 < %t > %t2
+; RUN: llvm-dwarfdump -debug-dump=info %t2 | FileCheck %s
+
+; Make sure the backend generates a single DIE and uses ref_addr.
+; CHECK: 0x[[BASE:.*]]: DW_TAG_structure_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "Base"
 ; CHECK-NOT: DW_TAG_structure_type
+; CHECK: 0x[[INT:.*]]: DW_TAG_base_type
+; CHECK-NEXT: DW_AT_name {{.*}} = "int"
+; CHECK-NOT: DW_TAG_base_type
+
+; CHECK: DW_TAG_compile_unit
+; CHECK: DW_TAG_formal_parameter
+; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[INT]])
+; CHECK: DW_TAG_variable
+; CHECK: DW_AT_type [DW_FORM_ref_addr] {{.*}}[[BASE]])
+
+; Make sure llvm-link only generates a single copy of the struct.
+; LINK: DW_TAG_structure_type
+; LINK-NOT: DW_TAG_structure_type
 ; Content of header files:
 ; struct Base {
 ;   int a;

diff --git a/test/Linker/type-unique-simple2.ll b/test/Linker/type-unique-simple2.ll
index 83e4715bf0dbdba6ead0c0cf45acc9b249146b48..ead91df6da1569103e887b0b326447b32c6f3131 100644 (file)
--- a/test/Linker/type-unique-simple2.ll
+++ b/test/Linker/type-unique-simple2.ll
@@ -2,3 +2,5 @@
 
 ; RUN: llvm-link %S/Inputs/type-unique-simple2-a.ll %S/Inputs/type-unique-simple2-b.ll -S -o %t
 ; RUN: cat %t | FileCheck %S/Inputs/type-unique-simple2-a.ll -check-prefix=LINK
+; RUN: llc -filetype=obj -O0 < %t > %t2
+; RUN: llvm-dwarfdump -debug-dump=info %t2 | FileCheck %S/Inputs/type-unique-simple2-a.ll