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reland: [DAG] Fix PR45049: LegalizeTypes crash 

Sometimes LegalizeTypes knows about common subexpressions before SelectionDAG
does, leading to accidental SDValue removal before its reference count was
truly zero.

Differential Revision: https://reviews.llvm.org/D76994

Reviewed-By: bjope

Fixes: https://bugs.llvm.org/show_bug.cgi?id=45049

Reverted in 3ce77142a6 because the previous patch
broke the expensive-checks bots. The new patch removes the broken check.
This commit is contained in:
Jonathan Roelofs 2020-03-28 12:55:51 -06:00 committed by Jon Roelofs
parent d2f1cd5d97
commit 41f13f1f64
3 changed files with 37 additions and 13 deletions
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2
llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.cpp
View File

@ -178,6 +178,7 @@ void DAGTypeLegalizer::PerformExpensiveChecks() {
}
}
#ifndef NDEBUG
// Checked that NewNodes are only used by other NewNodes.
for (unsigned i = 0, e = NewNodes.size(); i != e; ++i) {
SDNode *N = NewNodes[i];
@ -185,6 +186,7 @@ void DAGTypeLegalizer::PerformExpensiveChecks() {
UI != UE; ++UI)
assert(UI->getNodeId() == NewNode && "NewNode used by non-NewNode!");
}
#endif
}
/// This is the main entry point for the type legalizer. This does a top-down

33
llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
View File

@ -159,7 +159,9 @@ private:
const SDValue &getSDValue(TableId &Id) {
RemapId(Id);
assert(Id && "TableId should be non-zero");
return IdToValueMap[Id];
auto I = IdToValueMap.find(Id);
assert(I != IdToValueMap.end() && "cannot find Id in map");
return I->second;
}
public:
@ -176,25 +178,30 @@ public:
bool run();
void NoteDeletion(SDNode *Old, SDNode *New) {
assert(Old != New && "node replaced with self");
for (unsigned i = 0, e = Old->getNumValues(); i != e; ++i) {
TableId NewId = getTableId(SDValue(New, i));
TableId OldId = getTableId(SDValue(Old, i));
if (OldId != NewId)
if (OldId != NewId) {
ReplacedValues[OldId] = NewId;
// Delete Node from tables.
// Delete Node from tables. We cannot do this when OldId == NewId,
// because NewId can still have table references to it in
// ReplacedValues.
IdToValueMap.erase(OldId);
PromotedIntegers.erase(OldId);
ExpandedIntegers.erase(OldId);
SoftenedFloats.erase(OldId);
PromotedFloats.erase(OldId);
SoftPromotedHalfs.erase(OldId);
ExpandedFloats.erase(OldId);
ScalarizedVectors.erase(OldId);
SplitVectors.erase(OldId);
WidenedVectors.erase(OldId);
}
ValueToIdMap.erase(SDValue(Old, i));
IdToValueMap.erase(OldId);
PromotedIntegers.erase(OldId);
ExpandedIntegers.erase(OldId);
SoftenedFloats.erase(OldId);
PromotedFloats.erase(OldId);
SoftPromotedHalfs.erase(OldId);
ExpandedFloats.erase(OldId);
ScalarizedVectors.erase(OldId);
SplitVectors.erase(OldId);
WidenedVectors.erase(OldId);
}
}

15
llvm/test/CodeGen/X86/legalize-types-remapid.ll
View File

@ -14,3 +14,18 @@ bb1:
store volatile i32 %t0.i0.cast.i1, i32* @c
ret void
}
define void @PR45049() local_unnamed_addr {
so_basic:
%a0 = load i1, i1* undef, align 1
%a1 = select i1 %a0, i542 4374501449566023848745004454235242730706338861786424872851541212819905998398751846447026354046107648, i542 0 ; constant is: i542 1 << 331
%a00 = zext i1 %a0 to i542
%a11 = shl i542 %a00, 331
%a2 = shl i542 %a00, 330
%a4 = or i542 %a1, %a2
%a05 = zext i1 %a0 to i488
%a55 = shl i488 %a05, 111
store i542 %a4, i542* undef, align 8
store i488 %a55, i488* undef, align 8
ret void
}