[llvm] r321364 - [DAG] Integrate findBaseOffset address analyses to BaseIndexOffset. NFCI.
Michael Kruse via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 22 10:45:46 PST 2017
Hi,
this commit caused the miscompilation of three test-suite programs:
LinearDependence-dbl.execution_time
tramp3d-v4.execution_time
pointer_member.execution_time
See:
http://lab.llvm.org:8011/builders/perf-x86_64-penryn-O3-polly-unprofitable/builds/10187
(Obsequi.execution_time was fixed by me in r321371)
Could you have a look why this NFCI commit caused this? Thank you.
Michael
2017-12-22 17:59 GMT+01:00 Nirav Dave via llvm-commits
<llvm-commits at lists.llvm.org>:
> Author: niravd
> Date: Fri Dec 22 08:59:09 2017
> New Revision: 321364
>
> URL: http://llvm.org/viewvc/llvm-project?rev=321364&view=rev
> Log:
> [DAG] Integrate findBaseOffset address analyses to BaseIndexOffset. NFCI.
>
> BaseIndexOffset supercedes findBaseOffset analysis save only Constant
> Pool addresses. Migrate analysis to BaseIndexOffset.
>
> Modified:
> llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=321364&r1=321363&r2=321364&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Fri Dec 22 08:59:09 2017
> @@ -17405,43 +17405,6 @@ SDValue DAGCombiner::buildSqrtEstimate(S
> return buildSqrtEstimateImpl(Op, Flags, false);
> }
>
> -/// Return true if base is a frame index, which is known not to alias with
> -/// anything but itself. Provides base object and offset as results.
> -static bool findBaseOffset(SDValue Ptr, SDValue &Base, int64_t &Offset,
> - const GlobalValue *&GV, const void *&CV) {
> - // Assume it is a primitive operation.
> - Base = Ptr; Offset = 0; GV = nullptr; CV = nullptr;
> -
> - // If it's an adding a simple constant then integrate the offset.
> - if (Base.getOpcode() == ISD::ADD) {
> - if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Base.getOperand(1))) {
> - Base = Base.getOperand(0);
> - Offset += C->getSExtValue();
> - }
> - }
> -
> - // Return the underlying GlobalValue, and update the Offset. Return false
> - // for GlobalAddressSDNode since the same GlobalAddress may be represented
> - // by multiple nodes with different offsets.
> - if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Base)) {
> - GV = G->getGlobal();
> - Offset += G->getOffset();
> - return false;
> - }
> -
> - // Return the underlying Constant value, and update the Offset. Return false
> - // for ConstantSDNodes since the same constant pool entry may be represented
> - // by multiple nodes with different offsets.
> - if (ConstantPoolSDNode *C = dyn_cast<ConstantPoolSDNode>(Base)) {
> - CV = C->isMachineConstantPoolEntry() ? (const void *)C->getMachineCPVal()
> - : (const void *)C->getConstVal();
> - Offset += C->getOffset();
> - return false;
> - }
> - // If it's any of the following then it can't alias with anything but itself.
> - return isa<FrameIndexSDNode>(Base);
> -}
> -
> /// Return true if there is any possibility that the two addresses overlap.
> bool DAGCombiner::isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) const {
> // If they are the same then they must be aliases.
> @@ -17483,39 +17446,16 @@ bool DAGCombiner::isAlias(LSBaseSDNode *
> return false;
> }
>
> - // FIXME: findBaseOffset and ConstantValue/GlobalValue/FrameIndex analysis
> - // modified to use BaseIndexOffset.
> -
> - // Gather base node and offset information.
> - SDValue Base0, Base1;
> - int64_t Offset0, Offset1;
> - const GlobalValue *GV0, *GV1;
> - const void *CV0, *CV1;
> - bool IsFrameIndex0 = findBaseOffset(Op0->getBasePtr(),
> - Base0, Offset0, GV0, CV0);
> - bool IsFrameIndex1 = findBaseOffset(Op1->getBasePtr(),
> - Base1, Offset1, GV1, CV1);
> -
> - // If they have the same base address, then check to see if they overlap.
> - if (Base0 == Base1 || (GV0 && (GV0 == GV1)) || (CV0 && (CV0 == CV1)))
> - return !((Offset0 + NumBytes0) <= Offset1 ||
> - (Offset1 + NumBytes1) <= Offset0);
> -
> - // It is possible for different frame indices to alias each other, mostly
> - // when tail call optimization reuses return address slots for arguments.
> - // To catch this case, look up the actual index of frame indices to compute
> - // the real alias relationship.
> - if (IsFrameIndex0 && IsFrameIndex1) {
> - MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
> - Offset0 += MFI.getObjectOffset(cast<FrameIndexSDNode>(Base0)->getIndex());
> - Offset1 += MFI.getObjectOffset(cast<FrameIndexSDNode>(Base1)->getIndex());
> - return !((Offset0 + NumBytes0) <= Offset1 ||
> - (Offset1 + NumBytes1) <= Offset0);
> - }
> -
> - // Otherwise, if we know what the bases are, and they aren't identical, then
> - // we know they cannot alias.
> - if ((IsFrameIndex0 || CV0 || GV0) && (IsFrameIndex1 || CV1 || GV1))
> + bool IsFI0 = isa<FrameIndexSDNode>(BasePtr0.getBase());
> + bool IsFI1 = isa<FrameIndexSDNode>(BasePtr1.getBase());
> + bool IsGV0 = isa<GlobalAddressSDNode>(BasePtr0.getBase());
> + bool IsGV1 = isa<GlobalAddressSDNode>(BasePtr1.getBase());
> + bool IsCV0 = isa<ConstantPoolSDNode>(BasePtr0.getBase());
> + bool IsCV1 = isa<ConstantPoolSDNode>(BasePtr1.getBase());
> +
> + // Matched types are already handled above. So if this is true they
> + // cannot alias.
> + if ((IsFI0 || IsGV0 || IsCV0) && (IsFI1 || IsGV1 || IsCV1))
> return false;
>
> // If we know required SrcValue1 and SrcValue2 have relatively large alignment
>
> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp?rev=321364&r1=321363&r2=321364&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp (original)
> +++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp Fri Dec 22 08:59:09 2017
> @@ -37,6 +37,23 @@ bool BaseIndexOffset::equalBaseIndex(Bas
> return true;
> }
>
> + // Match Constants
> + if (auto *A = dyn_cast<ConstantPoolSDNode>(Base))
> + if (auto *B = dyn_cast<ConstantPoolSDNode>(Other.Base)) {
> + bool IsMatch =
> + A->isMachineConstantPoolEntry() == B->isMachineConstantPoolEntry();
> + if (IsMatch) {
> + if (A->isMachineConstantPoolEntry())
> + IsMatch = A->getMachineCPVal() == B->getMachineCPVal();
> + else
> + IsMatch = A->getConstVal() == B->getConstVal();
> + }
> + if (IsMatch) {
> + Off += B->getOffset() - A->getOffset();
> + return true;
> + }
> + }
> +
> const MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
>
> // Match non-equal FrameIndexes - If both frame indices are fixed
>
>
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