[llvm] r321380 - Revert "[DAG] Integrate findBaseOffset address analyses to BaseIndexOffset. NFCI."
Nirav Dave via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 22 11:33:56 PST 2017
Author: niravd
Date: Fri Dec 22 11:33:56 2017
New Revision: 321380
URL: http://llvm.org/viewvc/llvm-project?rev=321380&view=rev
Log:
Revert "[DAG] Integrate findBaseOffset address analyses to BaseIndexOffset. NFCI."
which was causing miscompilations in for some test-suite components.
This reverts commit 3e9de9ff0f3162920a2a3cba51c7dc14b54b4d16.
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=321380&r1=321379&r2=321380&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Fri Dec 22 11:33:56 2017
@@ -17405,6 +17405,43 @@ 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.
@@ -17446,16 +17483,39 @@ bool DAGCombiner::isAlias(LSBaseSDNode *
return false;
}
- 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))
+ // 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))
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=321380&r1=321379&r2=321380&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp Fri Dec 22 11:33:56 2017
@@ -37,23 +37,6 @@ 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
More information about the llvm-commits
mailing list