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Fix combiner-aa issue with bases which are different, but can alias.
Previously, it treated GV+28 GV+0 as different bases, and assumed they could not alias. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82753 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -6089,11 +6089,12 @@ SDValue DAGCombiner::BuildUDIV(SDNode *N) {
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return S;
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}
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/// FindBaseOffset - Return true if base is known not to alias with anything
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/// but itself. Provides base object and offset as results.
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static bool FindBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset) {
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/// FindBaseOffset - Return true if base is a frame index, which is known not
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// to alias with anything but itself. Provides base object and offset as results.
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static bool FindBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset,
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GlobalValue *&GV, void *&CV) {
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// Assume it is a primitive operation.
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Base = Ptr; Offset = 0;
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Base = Ptr; Offset = 0; GV = 0; CV = 0;
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// If it's an adding a simple constant then integrate the offset.
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if (Base.getOpcode() == ISD::ADD) {
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@ -6102,11 +6103,27 @@ static bool FindBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset) {
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Offset += C->getZExtValue();
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}
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}
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// Return the underlying GlobalValue, and update the Offset. Return false
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// for GlobalAddressSDNode since the same GlobalAddress may be represented
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// by multiple nodes with different offsets.
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if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Base)) {
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GV = G->getGlobal();
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Offset += G->getOffset();
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return false;
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}
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// Return the underlying Constant value, and update the Offset. Return false
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// for ConstantSDNodes since the same constant pool entry may be represented
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// by multiple nodes with different offsets.
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if (ConstantPoolSDNode *C = dyn_cast<ConstantPoolSDNode>(Base)) {
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CV = C->isMachineConstantPoolEntry() ? (void *)C->getMachineCPVal()
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: (void *)C->getConstVal();
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Offset += C->getOffset();
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return false;
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}
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// If it's any of the following then it can't alias with anything but itself.
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return isa<FrameIndexSDNode>(Base) ||
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isa<ConstantPoolSDNode>(Base) ||
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isa<GlobalAddressSDNode>(Base);
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return isa<FrameIndexSDNode>(Base);
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}
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/// isAlias - Return true if there is any possibility that the two addresses
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@ -6123,16 +6140,19 @@ bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
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// Gather base node and offset information.
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SDValue Base1, Base2;
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int64_t Offset1, Offset2;
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bool KnownBase1 = FindBaseOffset(Ptr1, Base1, Offset1);
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bool KnownBase2 = FindBaseOffset(Ptr2, Base2, Offset2);
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GlobalValue *GV1, *GV2;
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void *CV1, *CV2;
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bool isFrameIndex1 = FindBaseOffset(Ptr1, Base1, Offset1, GV1, CV1);
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bool isFrameIndex2 = FindBaseOffset(Ptr2, Base2, Offset2, GV2, CV2);
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// If they have a same base address then...
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if (Base1 == Base2)
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// Check to see if the addresses overlap.
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// If they have a same base address then check to see if they overlap.
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if (Base1 == Base2 || (GV1 && (GV1 == GV2)) || (CV1 && (CV1 == CV2)))
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return !((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
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// If we know both bases then they can't alias.
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if (KnownBase1 && KnownBase2) return false;
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// If we know what the bases are, and they aren't identical, then we know they
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// cannot alias.
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if ((isFrameIndex1 || CV1 || GV1) && (isFrameIndex2 || CV2 || GV2))
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return false;
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// If we know required SrcValue1 and SrcValue2 have relatively large alignment
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// compared to the size and offset of the access, we may be able to prove they
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