[llvm] r198397 - Debug Info: Type Units: Simplify type hashing using IR-provided unique names.
David Blaikie
dblaikie at gmail.com
Thu Jan 2 20:20:26 PST 2014
Author: dblaikie
Date: Thu Jan 2 22:20:26 2014
New Revision: 198397
URL: http://llvm.org/viewvc/llvm-project?rev=198397&view=rev
Log:
Debug Info: Type Units: Simplify type hashing using IR-provided unique names.
What's good for LTO metadata size problems ought to be good for non-LTO
debug info size too, so let's rely on the same uniqueness in both cases.
If it's insufficient for non-LTO for whatever reason (since we now won't
be uniquing CU-local types or any C types - but these are likely to not
be the most significant contributors to type bloat) we should consider a
frontend solution that'll help both LTO and non-LTO alike, rather than
using DWARF-level DIE-hashing that only helps non-LTO debug info size.
It's also much simpler this way and benefits C++ even more since we can
deduplicate lexically separate definitions of the same C++ type since
they have the same mangled name.
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
llvm/trunk/test/DebugInfo/X86/c-type-units.ll
llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=198397&r1=198396&r2=198397&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Thu Jan 2 22:20:26 2014
@@ -58,11 +58,6 @@ static cl::opt<bool> UnknownLocations(
cl::desc("Make an absence of debug location information explicit."),
cl::init(false));
-static cl::opt<bool>
-GenerateODRHash("generate-odr-hash", cl::Hidden,
- cl::desc("Add an ODR hash to external type DIEs."),
- cl::init(false));
-
static cl::opt<bool> GenerateCUHash("generate-cu-hash", cl::Hidden,
cl::desc("Add the CU hash as the dwo_id."),
cl::init(false));
@@ -1019,41 +1014,6 @@ void DwarfDebug::collectDeadVariables()
}
}
-// Type Signature [7.27] and ODR Hash code.
-
-/// \brief Grabs the string in whichever attribute is passed in and returns
-/// a reference to it. Returns "" if the attribute doesn't exist.
-static StringRef getDIEStringAttr(DIE *Die, unsigned Attr) {
- DIEValue *V = Die->findAttribute(Attr);
-
- if (DIEString *S = dyn_cast_or_null<DIEString>(V))
- return S->getString();
-
- return StringRef("");
-}
-
-/// Return true if the current DIE is contained within an anonymous namespace.
-static bool isContainedInAnonNamespace(DIE *Die) {
- DIE *Parent = Die->getParent();
-
- while (Parent) {
- if (Parent->getTag() == dwarf::DW_TAG_namespace &&
- getDIEStringAttr(Parent, dwarf::DW_AT_name) == "")
- return true;
- Parent = Parent->getParent();
- }
-
- return false;
-}
-
-/// Test if the current CU language is C++ and that we have
-/// a named type that is not contained in an anonymous namespace.
-static bool shouldAddODRHash(DwarfTypeUnit *CU, DIE *Die) {
- return CU->getLanguage() == dwarf::DW_LANG_C_plus_plus &&
- getDIEStringAttr(Die, dwarf::DW_AT_name) != "" &&
- !isContainedInAnonNamespace(Die);
-}
-
void DwarfDebug::finalizeModuleInfo() {
// Collect info for variables that were optimized out.
collectDeadVariables();
@@ -3041,8 +3001,8 @@ void DwarfDebug::emitDebugStrDWO() {
OffSec, StrSym);
}
-void DwarfDebug::addDwarfTypeUnitType(uint16_t Language, DIE *RefDie,
- DICompositeType CTy) {
+void DwarfDebug::addDwarfTypeUnitType(uint16_t Language, StringRef Identifier,
+ DIE *RefDie, DICompositeType CTy) {
const DwarfTypeUnit *&TU = DwarfTypeUnits[CTy];
if (!TU) {
DIE *UnitDie = new DIE(dwarf::DW_TAG_type_unit);
@@ -3057,16 +3017,14 @@ void DwarfDebug::addDwarfTypeUnitType(ui
DIE *Die = NewTU->createTypeDIE(CTy);
- if (GenerateODRHash && shouldAddODRHash(NewTU, Die))
- NewTU->addUInt(UnitDie, dwarf::DW_AT_GNU_odr_signature,
- dwarf::DW_FORM_data8,
- DIEHash().computeDIEODRSignature(*Die));
- // FIXME: This won't handle circularly referential structures, as the DIE
- // may have references to other DIEs still under construction and missing
- // their signature. Hashing should walk through the signatures to their
- // referenced type, or possibly walk the precomputed hashes of related types
- // at the end.
- uint64_t Signature = DIEHash().computeTypeSignature(*Die);
+ MD5 Hash;
+ Hash.update(Identifier);
+ // ... take the least significant 8 bytes and return those. Our MD5
+ // implementation always returns its results in little endian, swap bytes
+ // appropriately.
+ MD5::MD5Result Result;
+ Hash.final(Result);
+ uint64_t Signature = *reinterpret_cast<uint64_t *>(Result + 8);
NewTU->setTypeSignature(Signature);
NewTU->setType(Die);
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h?rev=198397&r1=198396&r2=198397&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Thu Jan 2 22:20:26 2014
@@ -695,7 +695,8 @@ public:
/// \brief Add a DIE to the set of types that we're going to pull into
/// type units.
- void addDwarfTypeUnitType(uint16_t Language, DIE *Die, DICompositeType CTy);
+ void addDwarfTypeUnitType(uint16_t Language, StringRef Identifier, DIE *Die,
+ DICompositeType CTy);
/// \brief Add a label so that arange data can be generated for it.
void addArangeLabel(SymbolCU SCU) { ArangeLabels.push_back(SCU); }
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=198397&r1=198396&r2=198397&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Thu Jan 2 22:20:26 2014
@@ -928,41 +928,6 @@ DIE *DwarfUnit::createTypeDIE(DIComposit
return TyDIE;
}
-/// Return true if the type is appropriately scoped to be contained inside
-/// its own type unit.
-static bool isDwarfTypeUnitScoped(DIType Ty, const DwarfDebug *DD) {
- DIScope Parent = DD->resolve(Ty.getContext());
- while (Parent) {
- // Don't generate a hash for anything scoped inside a function.
- if (Parent.isSubprogram())
- return false;
- Parent = DD->resolve(Parent.getContext());
- }
- return true;
-}
-
-/// Return true if the type should be split out into a type unit.
-static bool shouldCreateDwarfTypeUnit(DICompositeType CTy,
- const DwarfDebug *DD) {
- if (!GenerateDwarfTypeUnits)
- return false;
-
- uint16_t Tag = CTy.getTag();
-
- switch (Tag) {
- case dwarf::DW_TAG_structure_type:
- case dwarf::DW_TAG_union_type:
- case dwarf::DW_TAG_enumeration_type:
- case dwarf::DW_TAG_class_type:
- // If this is a class, structure, union, or enumeration type
- // that is a definition (not a declaration), and not scoped
- // inside a function then separate this out as a type unit.
- return !CTy.isForwardDecl() && isDwarfTypeUnitScoped(CTy, DD);
- default:
- return false;
- }
-}
-
/// getOrCreateTypeDIE - Find existing DIE or create new DIE for the
/// given DIType.
DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) {
@@ -989,11 +954,13 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const
constructTypeDIE(*TyDIE, DIBasicType(Ty));
else if (Ty.isCompositeType()) {
DICompositeType CTy(Ty);
- if (shouldCreateDwarfTypeUnit(CTy, DD)) {
- DD->addDwarfTypeUnitType(getLanguage(), TyDIE, CTy);
- // Skip updating the accellerator tables since this is not the full type
- return TyDIE;
- }
+ if (GenerateDwarfTypeUnits && !Ty.isForwardDecl())
+ if (MDString *TypeId = CTy.getIdentifier()) {
+ DD->addDwarfTypeUnitType(getLanguage(), TypeId->getString(), TyDIE,
+ CTy);
+ // Skip updating the accellerator tables since this is not the full type
+ return TyDIE;
+ }
constructTypeDIE(*TyDIE, CTy);
} else {
assert(Ty.isDerivedType() && "Unknown kind of DIType");
Modified: llvm/trunk/test/DebugInfo/X86/c-type-units.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/c-type-units.ll?rev=198397&r1=198396&r2=198397&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/c-type-units.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/c-type-units.ll Thu Jan 2 22:20:26 2014
@@ -5,8 +5,9 @@
; struct foo {
; } f;
-; CHECK: DW_TAG_type_unit
-; CHECK-NEXT: DW_AT_language [DW_FORM_data2] (0x000c)
+; no known LLVM frontends produce appropriate unique identifiers for C types,
+; so we don't produce type units for them
+; CHECK-NOT: DW_TAG_type_unit
%struct.foo = type {}
Modified: llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll?rev=198397&r1=198396&r2=198397&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/generate-odr-hash.ll Thu Jan 2 22:20:26 2014
@@ -1,6 +1,6 @@
; REQUIRES: object-emission
-; RUN: llc %s -o %t -filetype=obj -O0 -generate-type-units -generate-odr-hash -mtriple=x86_64-unknown-linux-gnu
+; RUN: llc %s -o %t -filetype=obj -O0 -generate-type-units -mtriple=x86_64-unknown-linux-gnu
; RUN: llvm-dwarfdump %t | FileCheck %s
; Generated from:
@@ -46,18 +46,31 @@
; CHECK-LABEL: .debug_info contents:
; CHECK: Compile Unit: length = [[CU_SIZE:[0-9a-f]+]]
+; CHECK: DW_TAG_structure_type
+; CHECK-NEXT: DW_AT_signature
+; CHECK: DW_TAG_class_type
+; CHECK-NEXT: DW_AT_signature
+
+; Ensure the CU-local type 'walrus' is not placed in a type unit.
+; CHECK: DW_TAG_structure_type
+; CHECK-NEXT: debug_str{{.*}}"walrus"
+; CHECK-NEXT: DW_AT_byte_size
+; CHECK-NEXT: DW_AT_decl_file
+; CHECK-NEXT: DW_AT_decl_line
+
; CHECK-LABEL: .debug_types contents:
; Check that we generate a hash for bar and the value.
-; CHECK-LABEL: type_signature = 0x6a7ee3d400662e88
-; CHECK: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x200520c0d5b90eff)
+; CHECK-NOT: type_signature
+; CHECK-LABEL: type_signature = 0x1d02f3be30cc5688
; CHECK: DW_TAG_structure_type
; CHECK-NEXT: debug_str{{.*}}"bar"
; Check that we generate a hash for fluffy and the value.
-; CHECK-LABEL: type_signature = 0x139b2e1ea94afec7
-; CHECK: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x9a0124d5a0c21c52)
+; CHECK-NOT: type_signature
+; CHECK-LABEL: type_signature = 0xb04af47397402e77
+; CHECK-NOT: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x9a0124d5a0c21c52)
; CHECK: DW_TAG_namespace
; CHECK-NEXT: debug_str{{.*}}"echidna"
; CHECK: DW_TAG_namespace
@@ -67,34 +80,22 @@
; CHECK: DW_TAG_class_type
; CHECK-NEXT: debug_str{{.*}}"fluffy"
-; namespace and won't violate any ODR-ness.
-; CHECK-LABEL: type_signature = 0xc0d031d6449dbca7
-; CHECK: DW_TAG_type_unit
-; CHECK-NOT: NULL
-; We emit no hash for walrus since the type is contained in an anonymous
-; CHECK-NOT: DW_AT_GNU_odr_signature
-; CHECK: DW_TAG_structure_type
-; CHECK-NEXT: debug_str{{.*}}"walrus"
-; CHECK-NEXT: DW_AT_byte_size
-; CHECK-NEXT: DW_AT_decl_file
-; CHECK-NEXT: DW_AT_decl_line
-; CHECK: DW_TAG_subprogram
-
; Check that we generate a hash for wombat and the value, but not for the
; anonymous type contained within.
-; CHECK-LABEL: type_signature = 0x73776f130648b986
-; CHECK: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x685bcc220141e9d7)
+; CHECK-NOT: type_signature
+; CHECK-LABEL: type_signature = 0xfd756cee88f8a118
+; CHECK-NOT: DW_AT_GNU_odr_signature [DW_FORM_data8] (0x685bcc220141e9d7)
; CHECK: DW_TAG_structure_type
; CHECK-NEXT: debug_str{{.*}}"wombat"
-; CHECK-LABEL: type_signature = 0xbf6fc40e82583d7c
+; CHECK-NOT: type_signature
+; CHECK-LABEL: type_signature = 0xe94f6d3843e62d6b
; CHECK: DW_TAG_type_unit
; CHECK-NOT: NULL
-; Check that we generate no ODR hash for the anonymous type nested inside 'wombat'
; CHECK-NOT: DW_AT_GNU_odr_signature
; CHECK: DW_TAG_structure_type
; The signature for the outer 'wombat' type
-; CHECK: DW_AT_signature [DW_FORM_ref_sig8] (0x73776f130648b986)
+; CHECK: DW_AT_signature [DW_FORM_ref_sig8] (0xfd756cee88f8a118)
; CHECK: DW_TAG_structure_type
; CHECK-NOT: DW_AT_name
; CHECK-NOT: DW_AT_GNU_odr_signature
@@ -107,18 +108,16 @@
; Don't emit pubtype entries for type DIEs in the compile unit that just indirect to a type unit.
; CHECK-NEXT: unit_size = [[CU_SIZE]]
; CHECK-NEXT: Offset Name
+; CHECK-NEXT: "walrus"
; Type unit for 'bar'
-; CHECK-NEXT: unit_size = 0x0000002b
+; CHECK-NEXT: unit_size = 0x00000023
; CHECK-NEXT: Offset Name
; CHECK-NEXT: "bar"
-; CHECK-NEXT: unit_size = 0x00000065
+; CHECK-NEXT: unit_size = 0x0000005d
; CHECK-NEXT: Offset Name
; CHECK-NEXT: "int"
; CHECK-NEXT: "echidna::capybara::mongoose::fluffy"
-; CHECK-NEXT: unit_size = 0x0000003b
-; CHECK-NEXT: Offset Name
-; CHECK-NEXT: "walrus"
-; CHECK-NEXT: unit_size = 0x00000042
+; CHECK-NEXT: unit_size = 0x0000003a
; CHECK-NEXT: Offset Name
; CHECK-NEXT: "wombat"
; CHECK-NEXT: unit_size = 0x0000004b
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