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[SelectionDAG] Support multiple dangling debug info for one value
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Summary:
When building the selection DAG we sometimes need to postpone
the handling of a dbg.value until the value it should refer to
is created. This is done by using the DanglingDebugInfoMap.
In the past this map has been limited to hold one dangling
dbg.value per value. This patch removes that restriction.

Reviewers: aprantl, rnk, probinson, vsk

Reviewed By: aprantl

Subscribers: Ka-Ka, llvm-commits, JDevlieghere

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D44610

llvm-svn: 328084
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@bjope
bjope committed Mar 21, 2018
1 parent 95f7572 commit 5c25f88
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Showing 3 changed files with 59 additions and 65 deletions.
95 changes: 46 additions & 49 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View file
Expand Up @@ -1080,62 +1080,59 @@ void SelectionDAGBuilder::visit(unsigned Opcode, const User &I) {

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 &DDIMI : DanglingDebugInfoMap)
for (auto &DDI : DDIMI.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");
DDI = DanglingDebugInfo();
}
}
}
}

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())
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);
DanglingDebugInfoVector &DDIV = DanglingDebugInfoMap[V];
for (auto &DDI : DDIV) {
if (!DDI.getDI())
continue;
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() << "Resolved dangling debug info for " << *DI
<< "in EmitFuncArgumentDbgValue\n");
} else
DEBUG(dbgs() << "Resolved dangling debug info for " << *DI
<< "in EmitFuncArgumentDbgValue\n");
} else
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
DanglingDebugInfoMap[V] = DanglingDebugInfo();
DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
}
DanglingDebugInfoMap[V].clear();
}

/// getCopyFromRegs - If there was virtual register allocated for the value V
Expand Down Expand Up @@ -5330,7 +5327,7 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
// Do not call getValue(V) yet, as we don't want to generate code.
// Remember it for later.
DanglingDebugInfo DDI(&DI, dl, SDNodeOrder);
DanglingDebugInfoMap[V] = DDI;
DanglingDebugInfoMap[V].push_back(DDI);
return nullptr;
}

Expand Down
5 changes: 4 additions & 1 deletion llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
View file
Expand Up @@ -116,9 +116,12 @@ class SelectionDAGBuilder {
unsigned getSDNodeOrder() { return SDNodeOrder; }
};

/// DanglingDebugInfoVector - Helper type for DanglingDebugInfoMap.
typedef std::vector<DanglingDebugInfo> DanglingDebugInfoVector;

/// DanglingDebugInfoMap - Keeps track of dbg_values for which we have not
/// yet seen the referent. We defer handling these until we do see it.
DenseMap<const Value*, DanglingDebugInfo> DanglingDebugInfoMap;
DenseMap<const Value*, DanglingDebugInfoVector> DanglingDebugInfoMap;

public:
/// PendingLoads - Loads are not emitted to the program immediately. We bunch
Expand Down
24 changes: 9 additions & 15 deletions llvm/test/DebugInfo/X86/sdag-dangling-dbgvalue.ll
View file
Expand Up @@ -50,8 +50,8 @@
; 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"
; CHECK: ![[BAR5:.*]] = !DILocalVariable(name: "bar5"
; CHECK: ![[FOO5:.*]] = !DILocalVariable(name: "foo5"


source_filename = "sdag-dangling-dbgvalue.c"
Expand All @@ -74,27 +74,23 @@ entry1:
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.
; Verify that the def comes before the debug-use for foo2 and bar2.
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, ![[FOO2]], !DIExpression()
; 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.
; Verify that the def comes before the debug-use for foo3 and bar3.
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, ![[BAR3]], !DIExpression()
; 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
Expand All @@ -118,15 +114,13 @@ entry4:
}

; 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-NEXT: [[REG5:%[0-9]+]]:gr64 =
; CHECK-NEXT: DBG_VALUE debug-use [[REG5]], debug-use $noreg, ![[BAR5]], !DIExpression()
; CHECK-NOT: DBG_VALUE debug-use [[REG5]], debug-use $noreg, ![[FOO5]], !DIExpression()
; CHECK: RET
entry5:
call void @llvm.dbg.value(metadata %struct.SS* @S, metadata !49, metadata !DIExpression()), !dbg !51
Expand Down

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