Revert "[DAG] Rewrite areNonVolatileConsecutiveLoads to use BaseIndexOffset"

This reverts commit r306819 which appears be exposing underlying
issues in a stage1 ppc64be build

llvm-svn: 306820

2 files changed, 45 insertions, 20 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f41323bd08b..98553152117 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -34,7 +34,6 @@
 #include "llvm/CodeGen/MachineMemOperand.h"
 #include "llvm/CodeGen/MachineValueType.h"
 #include "llvm/CodeGen/RuntimeLibcalls.h"
-#include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
 #include "llvm/CodeGen/SelectionDAGNodes.h"
 #include "llvm/CodeGen/SelectionDAGTargetInfo.h"
 #include "llvm/CodeGen/ValueTypes.h"
@@ -7631,13 +7630,45 @@ bool SelectionDAG::areNonVolatileConsecutiveLoads(LoadSDNode *LD,
 
   SDValue Loc = LD->getOperand(1);
   SDValue BaseLoc = Base->getOperand(1);
-
-  auto BaseLocDecomp = BaseIndexOffset::match(BaseLoc, *this);
-  auto LocDecomp = BaseIndexOffset::match(Loc, *this);
-
-  int64_t Offset = 0;
-  if (BaseLocDecomp.equalBaseIndex(LocDecomp, *this, Offset))
-    return (Dist * Bytes == Offset);
+  if (Loc.getOpcode() == ISD::FrameIndex) {
+    if (BaseLoc.getOpcode() != ISD::FrameIndex)
+      return false;
+    const MachineFrameInfo &MFI = getMachineFunction().getFrameInfo();
+    int FI  = cast<FrameIndexSDNode>(Loc)->getIndex();
+    int BFI = cast<FrameIndexSDNode>(BaseLoc)->getIndex();
+    int FS  = MFI.getObjectSize(FI);
+    int BFS = MFI.getObjectSize(BFI);
+    if (FS != BFS || FS != (int)Bytes) return false;
+    return MFI.getObjectOffset(FI) == (MFI.getObjectOffset(BFI) + Dist*Bytes);
+  }
+
+  // Handle X + C.
+  if (isBaseWithConstantOffset(Loc)) {
+    int64_t LocOffset = cast<ConstantSDNode>(Loc.getOperand(1))->getSExtValue();
+    if (Loc.getOperand(0) == BaseLoc) {
+      // If the base location is a simple address with no offset itself, then
+      // the second load's first add operand should be the base address.
+      if (LocOffset == Dist * (int)Bytes)
+        return true;
+    } else if (isBaseWithConstantOffset(BaseLoc)) {
+      // The base location itself has an offset, so subtract that value from the
+      // second load's offset before comparing to distance * size.
+      int64_t BOffset =
+        cast<ConstantSDNode>(BaseLoc.getOperand(1))->getSExtValue();
+      if (Loc.getOperand(0) == BaseLoc.getOperand(0)) {
+        if ((LocOffset - BOffset) == Dist * (int)Bytes)
+          return true;
+      }
+    }
+  }
+  const GlobalValue *GV1 = nullptr;
+  const GlobalValue *GV2 = nullptr;
+  int64_t Offset1 = 0;
+  int64_t Offset2 = 0;
+  bool isGA1 = TLI->isGAPlusOffset(Loc.getNode(), GV1, Offset1);
+  bool isGA2 = TLI->isGAPlusOffset(BaseLoc.getNode(), GV2, Offset2);
+  if (isGA1 && isGA2 && GV1 == GV2)
+    return Offset1 == (Offset2 + Dist*Bytes);
   return false;
 }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
index cd256efd4c3..4e899ae6668 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -60,18 +60,12 @@ BaseIndexOffset BaseIndexOffset::match(SDValue Ptr, const SelectionDAG &DAG) {
   int64_t Offset = 0;
   bool IsIndexSignExt = false;
 
-  // Consume constant adds & ors with appropriate masking.
-  while (Base->getOpcode() == ISD::ADD || Base->getOpcode() == ISD::OR) {
-    if (auto *C = dyn_cast<ConstantSDNode>(Base->getOperand(1))) {
-      // Only consider ORs which act as adds.
-      if (Base->getOpcode() == ISD::OR &&
-          !DAG.MaskedValueIsZero(Base->getOperand(0), C->getAPIntValue()))
-        break;
-      Offset += C->getSExtValue();
-      Base = Base->getOperand(0);
-      continue;
-    }
-    break;
+  // Consume constant adds
+  while (Base->getOpcode() == ISD::ADD &&
+         isa<ConstantSDNode>(Base->getOperand(1))) {
+    int64_t POffset = cast<ConstantSDNode>(Base->getOperand(1))->getSExtValue();
+    Offset += POffset;
+    Base = Base->getOperand(0);
   }
 
   if (Base->getOpcode() == ISD::ADD) {