[llvm] r327303 - [SelectionDAG] Improve handling of dangling debug info
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Thu Mar 29 10:37:18 PDT 2018
I think you are right. I looked at the Statistics.cpp code and "source variables" means source variables with a DW_AT_locations or DW_AT_constant_value.
-- adrian
> On Mar 29, 2018, at 10:23 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
> But that shouldn't cause the DW_TAG_variable to not be present, right? we keep all the variables in the "variables" list off the subprogram to emit even in the case of optimizations eliminating a variable (then the variable is emitted, but without any DW_AT_location) - that was my understanding.
>
> On Thu, Mar 29, 2018 at 10:11 AM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>
>> On Mar 29, 2018, at 10:00 AM, David Blaikie <dblaikie at gmail.com <mailto:dblaikie at gmail.com>> wrote:
>>
>>
>>
>> On Thu, Mar 29, 2018 at 9:09 AM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>>
>>> On Mar 29, 2018, at 9:02 AM, David Blaikie <dblaikie at gmail.com <mailto:dblaikie at gmail.com>> wrote:
>>>
>>> Seeing about a 7.5% increase in (compressed) debug_loc (and 4.2% increase in debug_info) in one binary at Google.
>>
>> So I guess this is ... good news?
>>
>>>
>>> I haven't looked into it further - if you all think this is expected (an increase in debug location accuracy/granularity/etc would account for this sort of growth), I'm OK with it.
>>>
>>> If useful, I can look into some samples further - or you can (assuming an optimized Clang shows similar growth - I haven't checked yet).
>>
>> Would it be easy for you to run llvm-dwarfdump --statistics on before and after? That might tell us how many more variables are visible for the extra cost in size.
>>
>> Sure, in both cases llvm-dwarfdump printed:
>>
>> Location list overflows the debug_loc section.
>> error: failed to consume entire .debug_loc section
>>
>> The % improvements:
>>
>> Source functions: 0%
>> Inlined functions: 0%
>> Unique source variables: 11.19%
>> Source variables: 357.78%
>> Variables with locations: 15.09%
>> Scope bytes total: 8.39%
>> Scope bytes covered: 16.87%
>>
>> So what does the "source variables" mean? Changes to optimizations shouldn't increase the number of variables we put in the DWARF, right? (that's why there's the "variables" list off the subprogram - to keep track of variables even if they're totally optimized away)
>
> dwarfdump has no way of knowing what variables *should* be in the debug info, so if this patch added new DBG_VALUEs that were previously being dropped, we can see an increase in variables that were previously missing entirely because the only DBG_VALUE describing them was dropped by SDag.
>
> -- adrian
>>
>>>
>>> On Mon, Mar 12, 2018 at 11:05 AM Bjorn Pettersson via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>>> Author: bjope
>>> Date: Mon Mar 12 11:02:39 2018
>>> New Revision: 327303
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=327303&view=rev <http://llvm.org/viewvc/llvm-project?rev=327303&view=rev>
>>> Log:
>>> [SelectionDAG] Improve handling of dangling debug info
>>>
>>> Summary:
>>> 1) Make sure to discard dangling debug info if the variable (or
>>> variable fragment) is mapped to something new before we had a
>>> chance to resolve the dangling debug info.
>>>
>>> 2) When resolving debug info, make sure to bump the associated
>>> SDNodeOrder to ensure that the DBG_VALUE is emitted after the
>>> instruction that defines the value used in the DBG_VALUE.
>>> This will avoid a debug-use before def scenario as seen in
>>> https://bugs.llvm.org/show_bug.cgi?id=36417 <https://bugs.llvm.org/show_bug.cgi?id=36417>.
>>>
>>> The new test case, test/DebugInfo/X86/sdag-dangling-dbgvalue.ll,
>>> show some other limitations in how dangling debug info is
>>> handled in the SelectionDAG. Since we currently only support
>>> having one dangling dbg.value per Value, we will end up dropping
>>> debug info when there are more than one variable that is described
>>> by the same "dangling value".
>>>
>>> Reviewers: aprantl
>>>
>>> Reviewed By: aprantl
>>>
>>> Subscribers: aprantl, eraman, llvm-commits, JDevlieghere
>>>
>>> Tags: #debug-info
>>>
>>> Differential Revision: https://reviews.llvm.org/D44369 <https://reviews.llvm.org/D44369>
>>>
>>> Added:
>>> llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll
>>> Modified:
>>> llvm/trunk/include/llvm/IR/DebugInfoMetadata.h
>>> llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
>>> llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
>>> llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
>>> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
>>> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
>>> llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
>>>
>>> Modified: llvm/trunk/include/llvm/IR/DebugInfoMetadata.h
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/DebugInfoMetadata.h?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/DebugInfoMetadata.h?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/include/llvm/IR/DebugInfoMetadata.h (original)
>>> +++ llvm/trunk/include/llvm/IR/DebugInfoMetadata.h Mon Mar 12 11:02:39 2018
>>> @@ -2415,6 +2415,32 @@ public:
>>> static Optional<DIExpression *>
>>> createFragmentExpression(const DIExpression *Expr, unsigned OffsetInBits,
>>> unsigned SizeInBits);
>>> +
>>> + /// Determine the relative position of the fragments described by this
>>> + /// DIExpression and \p Other.
>>> + /// Returns -1 if this is entirely before Other, 0 if this and Other overlap,
>>> + /// 1 if this is entirely after Other.
>>> + int fragmentCmp(const DIExpression *Other) const {
>>> + auto Fragment1 = *getFragmentInfo();
>>> + auto Fragment2 = *Other->getFragmentInfo();
>>> + unsigned l1 = Fragment1.OffsetInBits;
>>> + unsigned l2 = Fragment2.OffsetInBits;
>>> + unsigned r1 = l1 + Fragment1.SizeInBits;
>>> + unsigned r2 = l2 + Fragment2.SizeInBits;
>>> + if (r1 <= l2)
>>> + return -1;
>>> + else if (r2 <= l1)
>>> + return 1;
>>> + else
>>> + return 0;
>>> + }
>>> +
>>> + /// Check if fragments overlap between this DIExpression and \p Other.
>>> + bool fragmentsOverlap(const DIExpression *Other) const {
>>> + if (!isFragment() || !Other->isFragment())
>>> + return true;
>>> + return fragmentCmp(Other) == 0;
>>> + }
>>> };
>>>
>>> /// Global variables.
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp Mon Mar 12 11:02:39 2018
>>> @@ -1107,7 +1107,7 @@ void CodeViewDebug::calculateRanges(
>>> auto J = std::next(I);
>>> const DIExpression *DIExpr = DVInst->getDebugExpression();
>>> while (J != E &&
>>> - !fragmentsOverlap(DIExpr, J->first->getDebugExpression()))
>>> + !DIExpr->fragmentsOverlap(J->first->getDebugExpression()))
>>> ++J;
>>> if (J != E)
>>> End = getLabelBeforeInsn(J->first);
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp Mon Mar 12 11:02:39 2018
>>> @@ -123,29 +123,6 @@ MCSymbol *DebugHandlerBase::getLabelAfte
>>> return LabelsAfterInsn.lookup(MI);
>>> }
>>>
>>> -int DebugHandlerBase::fragmentCmp(const DIExpression *P1,
>>> - const DIExpression *P2) {
>>> - auto Fragment1 = *P1->getFragmentInfo();
>>> - auto Fragment2 = *P2->getFragmentInfo();
>>> - unsigned l1 = Fragment1.OffsetInBits;
>>> - unsigned l2 = Fragment2.OffsetInBits;
>>> - unsigned r1 = l1 + Fragment1.SizeInBits;
>>> - unsigned r2 = l2 + Fragment2.SizeInBits;
>>> - if (r1 <= l2)
>>> - return -1;
>>> - else if (r2 <= l1)
>>> - return 1;
>>> - else
>>> - return 0;
>>> -}
>>> -
>>> -bool DebugHandlerBase::fragmentsOverlap(const DIExpression *P1,
>>> - const DIExpression *P2) {
>>> - if (!P1->isFragment() || !P2->isFragment())
>>> - return true;
>>> - return fragmentCmp(P1, P2) == 0;
>>> -}
>>> -
>>> /// If this type is derived from a base type then return base type size.
>>> uint64_t DebugHandlerBase::getBaseTypeSize(const DITypeRef TyRef) {
>>> DIType *Ty = TyRef.resolve();
>>> @@ -232,8 +209,8 @@ void DebugHandlerBase::beginFunction(con
>>> const DIExpression *Fragment = I->first->getDebugExpression();
>>> if (std::all_of(Ranges.begin(), I,
>>> [&](DbgValueHistoryMap::InstrRange Pred) {
>>> - return !fragmentsOverlap(
>>> - Fragment, Pred.first->getDebugExpression());
>>> + return !Fragment->fragmentsOverlap(
>>> + Pred.first->getDebugExpression());
>>> }))
>>> LabelsBeforeInsn[I->first] = Asm->getFunctionBegin();
>>> else
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h (original)
>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugHandlerBase.h Mon Mar 12 11:02:39 2018
>>> @@ -122,14 +122,6 @@ public:
>>> /// Return Label immediately following the instruction.
>>> MCSymbol *getLabelAfterInsn(const MachineInstr *MI);
>>>
>>> - /// Determine the relative position of the fragments described by P1 and P2.
>>> - /// Returns -1 if P1 is entirely before P2, 0 if P1 and P2 overlap, 1 if P1 is
>>> - /// entirely after P2.
>>> - static int fragmentCmp(const DIExpression *P1, const DIExpression *P2);
>>> -
>>> - /// Determine whether two variable fragments overlap.
>>> - static bool fragmentsOverlap(const DIExpression *P1, const DIExpression *P2);
>>> -
>>> /// If this type is derived from a base type then return base type size.
>>> static uint64_t getBaseTypeSize(const DITypeRef TyRef);
>>> };
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Mon Mar 12 11:02:39 2018
>>> @@ -919,8 +919,7 @@ bool DebugLocEntry::MergeValues(const De
>>> // sorted.
>>> for (unsigned i = 0, j = 0; i < Values.size(); ++i) {
>>> for (; j < Next.Values.size(); ++j) {
>>> - int res = DebugHandlerBase::fragmentCmp(
>>> - cast<DIExpression>(Values[i].Expression),
>>> + int res = cast<DIExpression>(Values[i].Expression)->fragmentCmp(
>>> cast<DIExpression>(Next.Values[j].Expression));
>>> if (res == 0) // The two expressions overlap, we can't merge.
>>> return false;
>>> @@ -983,7 +982,7 @@ DwarfDebug::buildLocationList(SmallVecto
>>> // If this fragment overlaps with any open ranges, truncate them.
>>> const DIExpression *DIExpr = Begin->getDebugExpression();
>>> auto Last = remove_if(OpenRanges, [&](DebugLocEntry::Value R) {
>>> - return fragmentsOverlap(DIExpr, R.getExpression());
>>> + return DIExpr->fragmentsOverlap(R.getExpression());
>>> });
>>> OpenRanges.erase(Last, OpenRanges.end());
>>>
>>>
>>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Mon Mar 12 11:02:39 2018
>>> @@ -12,6 +12,7 @@
>>> //===----------------------------------------------------------------------===//
>>>
>>> #include "SelectionDAGBuilder.h"
>>> +#include "SDNodeDbgValue.h"
>>> #include "llvm/ADT/APFloat.h"
>>> #include "llvm/ADT/APInt.h"
>>> #include "llvm/ADT/ArrayRef.h"
>>> @@ -1077,29 +1078,64 @@ void SelectionDAGBuilder::visit(unsigned
>>> }
>>> }
>>>
>>> +void SelectionDAGBuilder::dropDanglingDebugInfo(const DILocalVariable *Variable,
>>> + const DIExpression *Expr) {
>>> + SmallVector<const Value *, 4> ToRemove;
>>> + for (auto &DMI : DanglingDebugInfoMap) {
>>> + DanglingDebugInfo &DDI = DMI.second;
>>> + if (DDI.getDI()) {
>>> + const DbgValueInst *DI = DDI.getDI();
>>> + DIVariable *DanglingVariable = DI->getVariable();
>>> + DIExpression *DanglingExpr = DI->getExpression();
>>> + if (DanglingVariable == Variable &&
>>> + Expr->fragmentsOverlap(DanglingExpr)) {
>>> + DEBUG(dbgs() << "Dropping dangling debug info for " << *DI << "\n");
>>> + ToRemove.push_back(DMI.first);
>>> + }
>>> + }
>>> + }
>>> +
>>> + for (auto V : ToRemove)
>>> + DanglingDebugInfoMap[V] = DanglingDebugInfo();
>>> +}
>>> +
>>> // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
>>> // generate the debug data structures now that we've seen its definition.
>>> void SelectionDAGBuilder::resolveDanglingDebugInfo(const Value *V,
>>> SDValue Val) {
>>> DanglingDebugInfo &DDI = DanglingDebugInfoMap[V];
>>> - if (DDI.getDI()) {
>>> - const DbgValueInst *DI = DDI.getDI();
>>> - DebugLoc dl = DDI.getdl();
>>> - unsigned DbgSDNodeOrder = DDI.getSDNodeOrder();
>>> - DILocalVariable *Variable = DI->getVariable();
>>> - DIExpression *Expr = DI->getExpression();
>>> - assert(Variable->isValidLocationForIntrinsic(dl) &&
>>> - "Expected inlined-at fields to agree");
>>> - SDDbgValue *SDV;
>>> - if (Val.getNode()) {
>>> - if (!EmitFuncArgumentDbgValue(V, Variable, Expr, dl, false, Val)) {
>>> - SDV = getDbgValue(Val, Variable, Expr, dl, DbgSDNodeOrder);
>>> - DAG.AddDbgValue(SDV, Val.getNode(), false);
>>> - }
>>> + if (!DDI.getDI())
>>> + return;
>>> + const DbgValueInst *DI = DDI.getDI();
>>> + DebugLoc dl = DDI.getdl();
>>> + unsigned ValSDNodeOrder = Val.getNode()->getIROrder();
>>> + unsigned DbgSDNodeOrder = DDI.getSDNodeOrder();
>>> + DILocalVariable *Variable = DI->getVariable();
>>> + DIExpression *Expr = DI->getExpression();
>>> + assert(Variable->isValidLocationForIntrinsic(dl) &&
>>> + "Expected inlined-at fields to agree");
>>> + SDDbgValue *SDV;
>>> + if (Val.getNode()) {
>>> + if (!EmitFuncArgumentDbgValue(V, Variable, Expr, dl, false, Val)) {
>>> + DEBUG(dbgs() << "Resolve dangling debug info [order=" << DbgSDNodeOrder
>>> + << "] for:\n " << *DI << "\n");
>>> + DEBUG(dbgs() << " By mapping to:\n "; Val.dump());
>>> + // Increase the SDNodeOrder for the DbgValue here to make sure it is
>>> + // inserted after the definition of Val when emitting the instructions
>>> + // after ISel. An alternative could be to teach
>>> + // ScheduleDAGSDNodes::EmitSchedule to delay the insertion properly.
>>> + DEBUG(if (ValSDNodeOrder > DbgSDNodeOrder)
>>> + dbgs() << "changing SDNodeOrder from " << DbgSDNodeOrder
>>> + << " to " << ValSDNodeOrder << "\n");
>>> + SDV = getDbgValue(Val, Variable, Expr, dl,
>>> + std::max(DbgSDNodeOrder, ValSDNodeOrder));
>>> + DAG.AddDbgValue(SDV, Val.getNode(), false);
>>> } else
>>> - DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
>>> - DanglingDebugInfoMap[V] = DanglingDebugInfo();
>>> - }
>>> + DEBUG(dbgs() << "Resolved dangling debug info for " << *DI
>>> + << "in EmitFuncArgumentDbgValue\n");
>>> + } else
>>> + DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
>>> + DanglingDebugInfoMap[V] = DanglingDebugInfo();
>>> }
>>>
>>> /// getCopyFromRegs - If there was virtual register allocated for the value V
>>> @@ -5178,6 +5214,7 @@ SelectionDAGBuilder::visitIntrinsicCall(
>>> const DbgInfoIntrinsic &DI = cast<DbgInfoIntrinsic>(I);
>>> DILocalVariable *Variable = DI.getVariable();
>>> DIExpression *Expression = DI.getExpression();
>>> + dropDanglingDebugInfo(Variable, Expression);
>>> assert(Variable && "Missing variable");
>>>
>>> // Check if address has undef value.
>>> @@ -5209,10 +5246,11 @@ SelectionDAGBuilder::visitIntrinsicCall(
>>> // DBG_VALUE instructions. llvm.dbg.declare is handled as a frame index in
>>> // the MachineFunction variable table.
>>> if (FI != std::numeric_limits<int>::max()) {
>>> - if (Intrinsic == Intrinsic::dbg_addr)
>>> - DAG.AddDbgValue(DAG.getFrameIndexDbgValue(Variable, Expression, FI, dl,
>>> - SDNodeOrder),
>>> - getRoot().getNode(), isParameter);
>>> + if (Intrinsic == Intrinsic::dbg_addr) {
>>> + SDDbgValue *SDV = DAG.getFrameIndexDbgValue(Variable, Expression,
>>> + FI, dl, SDNodeOrder);
>>> + DAG.AddDbgValue(SDV, getRoot().getNode(), isParameter);
>>> + }
>>> return nullptr;
>>> }
>>>
>>> @@ -5256,6 +5294,7 @@ SelectionDAGBuilder::visitIntrinsicCall(
>>>
>>> DILocalVariable *Variable = DI.getVariable();
>>> DIExpression *Expression = DI.getExpression();
>>> + dropDanglingDebugInfo(Variable, Expression);
>>> const Value *V = DI.getValue();
>>> if (!V)
>>> return nullptr;
>>> @@ -5280,6 +5319,12 @@ SelectionDAGBuilder::visitIntrinsicCall(
>>> return nullptr;
>>> }
>>>
>>> + // TODO: When we get here we will either drop the dbg.value completely, or
>>> + // we try to move it forward by letting it dangle for awhile. So we should
>>> + // probably add an extra DbgValue to the DAG here, with a reference to
>>> + // "noreg", to indicate that we have lost the debug location for the
>>> + // variable.
>>> +
>>> if (!V->use_empty() ) {
>>> // Do not call getValue(V) yet, as we don't want to generate code.
>>> // Remember it for later.
>>>
>>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
>>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Mon Mar 12 11:02:39 2018
>>> @@ -671,6 +671,12 @@ public:
>>> /// emit CopyFromReg of the specified type Ty. Return empty SDValue() otherwise.
>>> SDValue getCopyFromRegs(const Value *V, Type *Ty);
>>>
>>> + /// If we have dangling debug info that describes \p Variable, or an
>>> + /// overlapping part of variable considering the \p Expr, then this method
>>> + /// weill drop that debug info as it isn't valid any longer.
>>> + void dropDanglingDebugInfo(const DILocalVariable *Variable,
>>> + const DIExpression *Expr);
>>> +
>>> // resolveDanglingDebugInfo - if we saw an earlier dbg_value referring to V,
>>> // generate the debug data structures now that we've seen its definition.
>>> void resolveDanglingDebugInfo(const Value *V, SDValue Val);
>>>
>>> Modified: llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll?rev=327303&r1=327302&r2=327303&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll?rev=327303&r1=327302&r2=327303&view=diff>
>>> ==============================================================================
>>> --- llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll (original)
>>> +++ llvm/trunk/test/DebugInfo/X86/dbg-value-inlined-parameter.ll Mon Mar 12 11:02:39 2018
>>> @@ -32,10 +32,10 @@
>>> ;CHECK-NEXT: DW_AT_call_line
>>>
>>> ;CHECK: DW_TAG_formal_parameter
>>> +;FIXME: Linux shouldn't drop this parameter either...
>>> ;CHECK-NOT: DW_TAG
>>> -;FIXME: Shouldn't drop this parameter...
>>> -;XCHECK: DW_AT_abstract_origin {{.*}} "sp"
>>> -;XCHECK: DW_TAG_formal_parameter
>>> +;DARWIN: DW_AT_abstract_origin {{.*}} "sp"
>>> +;DARWIN: DW_TAG_formal_parameter
>>> ;CHECK: DW_AT_abstract_origin {{.*}} "nums"
>>> ;CHECK-NOT: DW_TAG_formal_parameter
>>>
>>>
>>> Added: llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll
>>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll?rev=327303&view=auto <http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll?rev=327303&view=auto>
>>> ==============================================================================
>>> --- llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll (added)
>>> +++ llvm/trunk/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll Mon Mar 12 11:02:39 2018
>>> @@ -0,0 +1,201 @@
>>> +; RUN: llc %s -stop-before expand-isel-pseudos -o - | FileCheck %s
>>> +
>>> +;--------------------------------------------------------------------
>>> +; This test case is basically generated from the following C code.
>>> +; Compiled with "--target=x86_64-apple-darwin -S -g -O3" to get debug
>>> +; info for optimized code.
>>> +;
>>> +; struct SS {
>>> +; int a;
>>> +; int b;
>>> +; } S = { .a = 23, .b = -17 };
>>> +;
>>> +; int test1() {
>>> +; struct SS* foo1 = &S;
>>> +; return (int)foo1;
>>> +; }
>>> +;
>>> +; int test2() {
>>> +; struct SS* foo2 = &S;
>>> +; struct SS* bar2 = &S;
>>> +; return (int)foo2 + (int)bar2;
>>> +; }
>>> +;
>>> +; int test3() {
>>> +; struct SS* bar3 = &S;
>>> +; struct SS* foo3 = &S;
>>> +; return (int)foo3 + (int)bar3;
>>> +; }
>>> +;
>>> +; int test4() {
>>> +; struct SS* foo4 = &S;
>>> +; struct SS* bar4 = &S;
>>> +; foo = 0;
>>> +; return (int)foo4 + (int)bar4;
>>> +; }
>>> +;
>>> +; int test5() {
>>> +; struct SS* bar5 = &S;
>>> +; struct SS* foo5 = &S;
>>> +; foo5 = 0;
>>> +; return (int)foo5 + (int)bar5;
>>> +; }
>>> +;--------------------------------------------------------------------
>>> +
>>> +; CHECK: ![[FOO1:.*]] = !DILocalVariable(name: "foo1"
>>> +; CHECK: ![[BAR1:.*]] = !DILocalVariable(name: "bar1"
>>> +; CHECK: ![[FOO2:.*]] = !DILocalVariable(name: "foo2"
>>> +; CHECK: ![[BAR2:.*]] = !DILocalVariable(name: "bar2"
>>> +; CHECK: ![[FOO3:.*]] = !DILocalVariable(name: "bar3"
>>> +; CHECK: ![[BAR3:.*]] = !DILocalVariable(name: "foo3"
>>> +; CHECK: ![[FOO4:.*]] = !DILocalVariable(name: "foo4"
>>> +; CHECK: ![[BAR4:.*]] = !DILocalVariable(name: "bar4"
>>> +; CHECK: ![[FOO5:.*]] = !DILocalVariable(name: "bar5"
>>> +; CHECK: ![[BAR5:.*]] = !DILocalVariable(name: "foo5"
>>> +
>>> +
>>> +source_filename = "sdag-dangling-dbgvalue.c"
>>> +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
>>> +target triple = "x86_64-apple-macosx10.4.0"
>>> +
>>> +%struct.SS = type { i32, i32 }
>>> +
>>> + at S = global %struct.SS { i32 23, i32 -17 }, align 4, !dbg !0
>>> +
>>> +; Verify that the def comes before the debug-use for foo1.
>>> +; TODO: Currently dbg.value for bar1 is dropped(?), is that expected?
>>> +define i32 @test1() local_unnamed_addr #0 !dbg !17 {
>>> +; CHECK-LABEL: bb.0.entry1
>>> +; CHECK-NEXT: [[REG1:%[0-9]+]]:gr64 =
>>> +; CHECK-NEXT: DBG_VALUE debug-use [[REG1]], debug-use $noreg, ![[FOO1]], !DIExpression()
>>> +entry1:
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !20, metadata !DIExpression()), !dbg !23
>>> + call void @llvm.dbg.value(metadata %struct.SS* null, metadata !22, metadata !DIExpression()), !dbg !24
>>> + ret i32 ptrtoint (%struct.SS* @S to i32), !dbg !25
>>> +}
>>> +
>>> +; Verify that the def comes before the debug-use for bar2.
>>> +; TODO: Currently dbg.value for foo2 is dropped. Seems to be a bug. The
>>> +; SelectionDAGBuilder should support several dangling dbg.value for the
>>> +; same value.
>>> +define i32 @test2() local_unnamed_addr #0 !dbg !26 {
>>> +; CHECK-LABEL: bb.0.entry2
>>> +; CHECK-NEXT: [[REG2:%[0-9]+]]:gr64 =
>>> +; CHECK-NEXT: DBG_VALUE debug-use [[REG2]], debug-use $noreg, ![[BAR2]], !DIExpression()
>>> +entry2:
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !28, metadata !DIExpression()), !dbg !30
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !29, metadata !DIExpression()), !dbg !31
>>> + ret i32 add (i32 ptrtoint (%struct.SS* @S to i32), i32 ptrtoint (%struct.SS* @S to i32)), !dbg !32
>>> +}
>>> +
>>> +; Verify that the def comes before the debug-use for foo3.
>>> +; TODO: Currently dbg.value for bar3 is dropped. Seems to be a bug. The
>>> +; SelectionDAGBuilder should support several dangling dbg.value for the
>>> +; same value.
>>> +define i32 @test3() local_unnamed_addr #0 !dbg !33 {
>>> +; CHECK-LABEL: bb.0.entry3
>>> +; CHECK-NEXT: [[REG3:%[0-9]+]]:gr64 =
>>> +; CHECK-NEXT: DBG_VALUE debug-use [[REG3]], debug-use $noreg, ![[FOO3]], !DIExpression()
>>> +entry3:
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !36, metadata !DIExpression()), !dbg !38
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !35, metadata !DIExpression()), !dbg !37
>>> + ret i32 add (i32 ptrtoint (%struct.SS* @S to i32), i32 ptrtoint (%struct.SS* @S to i32)), !dbg !39
>>> +}
>>> +
>>> +; Verify that the def comes before the debug-use for bar4.
>>> +; TODO: Currently dbg.value for foo4 is dropped. It is set to null and not
>>> +; used. Just like in test1 it can be discussed if there should be a
>>> +; DBG_VALUE for foo4 here.
>>> +define i32 @test4() local_unnamed_addr #0 !dbg !40 {
>>> +; CHECK-LABEL: bb.0.entry4
>>> +; CHECK-NEXT: [[REG4:%[0-9]+]]:gr64 =
>>> +; CHECK-NEXT: DBG_VALUE debug-use [[REG4]], debug-use $noreg, ![[BAR4]], !DIExpression()
>>> +entry4:
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !42, metadata !DIExpression()), !dbg !44
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !43, metadata !DIExpression()), !dbg !45
>>> + call void @llvm.dbg.value(metadata %struct.SS* null, metadata !42, metadata !DIExpression()), !dbg !44
>>> + ret i32 ptrtoint (%struct.SS* @S to i32), !dbg !46
>>> +}
>>> +
>>> +; Verify that we do not get a DBG_VALUE that maps foo5 to @S here.
>>> +; TODO: At the moment we do not get any DBG_VALUE at all here. If
>>> +; SelectionDAGBuilder should support several dangling dbg.value for the
>>> +; same value it would be possible to at least get a DBG_VALUE for
>>> +; bar5.
>>> +; TODO: foo5 is set to null, and it is not really used. Just like in test1 it
>>> +; can be discussed if there should be a DBG_VALUE for foo5 here.
>>> +define i32 @test5() local_unnamed_addr #0 !dbg !47 {
>>> +; CHECK-LABEL: bb.0.entry5:
>>> +; CHECK-NOT: DBG_VALUE
>>> +; CHECK: RET
>>> +entry5:
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !49, metadata !DIExpression()), !dbg !51
>>> + call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !50, metadata !DIExpression()), !dbg !52
>>> + call void @llvm.dbg.value(metadata %struct.SS* null, metadata !50, metadata !DIExpression()), !dbg !52
>>> + ret i32 ptrtoint (%struct.SS* @S to i32), !dbg !53
>>> +}
>>> +
>>> +; Function Attrs: nounwind readnone speculatable
>>> +declare void @llvm.dbg.value(metadata, metadata, metadata) #1
>>> +
>>> +attributes #0 = { nounwind readnone uwtable }
>>> +attributes #1 = { nounwind readnone speculatable }
>>> +
>>> +!llvm.dbg.cu <http://llvm.dbg.cu/> = !{!2}
>>> +!llvm.module.flags = !{!12, !13, !14, !15}
>>> +!llvm.ident = !{!16}
>>> +
>>> +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
>>> +!1 = distinct !DIGlobalVariable(name: "S", scope: !2, file: !3, line: 4, type: !8, isLocal: false, isDefinition: true)
>>> +!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 7.0.0 (trunk 327229) (llvm/trunk 327239)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !5, globals: !7)
>>> +!3 = !DIFile(filename: "sdag-dangling-dbgvalue.c", directory: "/repo/uabbpet/llvm-master")
>>> +!4 = !{}
>>> +!5 = !{!6}
>>> +!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
>>> +!7 = !{!0}
>>> +!8 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "SS", file: !3, line: 1, size: 64, elements: !9)
>>> +!9 = !{!10, !11}
>>> +!10 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !8, file: !3, line: 2, baseType: !6, size: 32)
>>> +!11 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !8, file: !3, line: 3, baseType: !6, size: 32, offset: 32)
>>> +!12 = !{i32 2, !"Dwarf Version", i32 2}
>>> +!13 = !{i32 2, !"Debug Info Version", i32 3}
>>> +!14 = !{i32 1, !"wchar_size", i32 4}
>>> +!15 = !{i32 7, !"PIC Level", i32 2}
>>> +!16 = !{!"clang version 7.0.0 (trunk 327229) (llvm/trunk 327239)"}
>>> +!17 = distinct !DISubprogram(name: "test1", scope: !3, file: !3, line: 6, type: !18, isLocal: false, isDefinition: true, scopeLine: 6, isOptimized: true, unit: !2, variables: !19)
>>> +!18 = !DISubroutineType(types: !5)
>>> +!19 = !{!20, !22}
>>> +!20 = !DILocalVariable(name: "foo1", scope: !17, file: !3, line: 7, type: !21)
>>> +!21 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 64)
>>> +!22 = !DILocalVariable(name: "bar1", scope: !17, file: !3, line: 8, type: !21)
>>> +!23 = !DILocation(line: 7, column: 14, scope: !17)
>>> +!24 = !DILocation(line: 8, column: 14, scope: !17)
>>> +!25 = !DILocation(line: 9, column: 3, scope: !17)
>>> +!26 = distinct !DISubprogram(name: "test2", scope: !3, file: !3, line: 12, type: !18, isLocal: false, isDefinition: true, scopeLine: 12, isOptimized: true, unit: !2, variables: !27)
>>> +!27 = !{!28, !29}
>>> +!28 = !DILocalVariable(name: "foo2", scope: !26, file: !3, line: 13, type: !21)
>>> +!29 = !DILocalVariable(name: "bar2", scope: !26, file: !3, line: 14, type: !21)
>>> +!30 = !DILocation(line: 13, column: 14, scope: !26)
>>> +!31 = !DILocation(line: 14, column: 14, scope: !26)
>>> +!32 = !DILocation(line: 15, column: 3, scope: !26)
>>> +!33 = distinct !DISubprogram(name: "test3", scope: !3, file: !3, line: 18, type: !18, isLocal: false, isDefinition: true, scopeLine: 18, isOptimized: true, unit: !2, variables: !34)
>>> +!34 = !{!35, !36}
>>> +!35 = !DILocalVariable(name: "bar3", scope: !33, file: !3, line: 19, type: !21)
>>> +!36 = !DILocalVariable(name: "foo3", scope: !33, file: !3, line: 20, type: !21)
>>> +!37 = !DILocation(line: 19, column: 14, scope: !33)
>>> +!38 = !DILocation(line: 20, column: 14, scope: !33)
>>> +!39 = !DILocation(line: 21, column: 3, scope: !33)
>>> +!40 = distinct !DISubprogram(name: "test4", scope: !3, file: !3, line: 24, type: !18, isLocal: false, isDefinition: true, scopeLine: 24, isOptimized: true, unit: !2, variables: !41)
>>> +!41 = !{!42, !43}
>>> +!42 = !DILocalVariable(name: "foo4", scope: !40, file: !3, line: 25, type: !21)
>>> +!43 = !DILocalVariable(name: "bar4", scope: !40, file: !3, line: 26, type: !21)
>>> +!44 = !DILocation(line: 25, column: 14, scope: !40)
>>> +!45 = !DILocation(line: 26, column: 14, scope: !40)
>>> +!46 = !DILocation(line: 28, column: 3, scope: !40)
>>> +!47 = distinct !DISubprogram(name: "test5", scope: !3, file: !3, line: 31, type: !18, isLocal: false, isDefinition: true, scopeLine: 31, isOptimized: true, unit: !2, variables: !48)
>>> +!48 = !{!49, !50}
>>> +!49 = !DILocalVariable(name: "bar5", scope: !47, file: !3, line: 32, type: !21)
>>> +!50 = !DILocalVariable(name: "foo5", scope: !47, file: !3, line: 33, type: !21)
>>> +!51 = !DILocation(line: 32, column: 14, scope: !47)
>>> +!52 = !DILocation(line: 33, column: 14, scope: !47)
>>> +!53 = !DILocation(line: 35, column: 3, scope: !47)
>>>
>>>
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