Revert "[codeview] support more DW_OPs for more complete debug info"

This reverts commit e160912f53f047bc97e572add179e08e33f4df48.

llvm-svn: 311977

1 files changed, 86 insertions, 105 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index ed2c263d320..8879f6b1f3e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -949,103 +949,13 @@ void CodeViewDebug::collectVariableInfoFromMFTable(
   }
 }
 
-void CodeViewDebug::calculateRanges(
-    LocalVariable &Var, const DbgValueHistoryMap::InstrRanges &Ranges) {
-  const TargetRegisterInfo *TRI = Asm->MF->getSubtarget().getRegisterInfo();
-
-  // calculate the definition ranges.
-  for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
-    const InsnRange &Range = *I;
-    const MachineInstr *DVInst = Range.first;
-    assert(DVInst->isDebugValue() && "Invalid History entry");
-    // FIXME: Find a way to represent constant variables, since they are
-    // relatively common.
-    DbgVariableLocation Location;
-    bool Supported =
-        DbgVariableLocation::extractFromMachineInstruction(Location, *DVInst);
-
-    // Because we cannot express DW_OP_deref in CodeView directly,
-    // we use a trick: we encode the type as a reference to the
-    // real type.
-    if (Var.Deref) {
-      // When we're encoding the type as a reference to the original type,
-      // we need to remove a level of indirection from incoming locations.
-      // E.g. [RSP+8] with DW_OP_deref becomes [RSP+8],
-      // and [RCX+0] without DW_OP_deref becomes RCX.
-      if (!Location.Deref) {
-        if (Location.InMemory)
-          Location.InMemory = false;
-        else
-          Supported = false;
-      }
-    } else if (Location.Deref) {
-      // We've encountered a Deref range when we had not applied the
-      // reference encoding. Start over using reference encoding.
-      Var.Deref = true;
-      Var.DefRanges.clear();
-      calculateRanges(Var, Ranges);
-      return;
-    }
-
-    // If we don't know how to handle this range, skip past it.
-    if (!Supported || (Location.Offset && !Location.InMemory))
-      continue;
-
-    // Handle the two cases we can handle: indirect in memory and in register.
-    {
-      LocalVarDefRange DR;
-      DR.CVRegister = TRI->getCodeViewRegNum(Location.Register);
-      DR.InMemory = Location.InMemory;
-      DR.DataOffset = Location.Offset;
-      if (Location.FragmentInfo) {
-        DR.IsSubfield = true;
-        DR.StructOffset = Location.FragmentInfo->OffsetInBits / 8;
-      } else {
-        DR.IsSubfield = false;
-        DR.StructOffset = 0;
-      }
-
-      if (Var.DefRanges.empty() ||
-          Var.DefRanges.back().isDifferentLocation(DR)) {
-        Var.DefRanges.emplace_back(std::move(DR));
-      }
-    }
-
-    // Compute the label range.
-    const MCSymbol *Begin = getLabelBeforeInsn(Range.first);
-    const MCSymbol *End = getLabelAfterInsn(Range.second);
-    if (!End) {
-      // This range is valid until the next overlapping bitpiece. In the
-      // common case, ranges will not be bitpieces, so they will overlap.
-      auto J = std::next(I);
-      const DIExpression *DIExpr = DVInst->getDebugExpression();
-      while (J != E &&
-             !fragmentsOverlap(DIExpr, J->first->getDebugExpression()))
-        ++J;
-      if (J != E)
-        End = getLabelBeforeInsn(J->first);
-      else
-        End = Asm->getFunctionEnd();
-    }
-
-    // If the last range end is our begin, just extend the last range.
-    // Otherwise make a new range.
-    SmallVectorImpl<std::pair<const MCSymbol *, const MCSymbol *>> &R =
-        Var.DefRanges.back().Ranges;
-    if (!R.empty() && R.back().second == Begin)
-      R.back().second = End;
-    else
-      R.emplace_back(Begin, End);
-
-    // FIXME: Do more range combining.
-  }
-}
-
 void CodeViewDebug::collectVariableInfo(const DISubprogram *SP) {
   DenseSet<InlinedVariable> Processed;
   // Grab the variable info that was squirreled away in the MMI side-table.
   collectVariableInfoFromMFTable(Processed);
 
+  const TargetRegisterInfo *TRI = Asm->MF->getSubtarget().getRegisterInfo();
+
   for (const auto &I : DbgValues) {
     InlinedVariable IV = I.first;
     if (Processed.count(IV))
@@ -1068,7 +978,89 @@ void CodeViewDebug::collectVariableInfo(const DISubprogram *SP) {
     LocalVariable Var;
     Var.DIVar = DIVar;
 
-    calculateRanges(Var, Ranges);
+    // Calculate the definition ranges.
+    for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
+      const InsnRange &Range = *I;
+      const MachineInstr *DVInst = Range.first;
+      assert(DVInst->isDebugValue() && "Invalid History entry");
+      const DIExpression *DIExpr = DVInst->getDebugExpression();
+      bool InMemory = DVInst->getOperand(1).isImm();
+      bool IsSubfield = false;
+      unsigned StructOffset = 0;
+      // Recognize a +Offset expression.
+      int Offset = 0;
+      DIExpressionCursor Ops(DIExpr);
+      auto Op = Ops.peek();
+      if (Op && Op->getOp() == dwarf::DW_OP_plus_uconst) {
+        Offset = Op->getArg(0);
+        Ops.take();
+      }
+
+      // Handle fragments.
+      auto Fragment = Ops.getFragmentInfo();
+      if (Fragment) {
+        IsSubfield = true;
+        StructOffset = Fragment->OffsetInBits / 8;
+      }
+      // Ignore unrecognized exprs.
+      if (Ops.peek() && Ops.peek()->getOp() != dwarf::DW_OP_LLVM_fragment)
+        continue;
+      if (!InMemory && Offset)
+        continue;
+
+      // Bail if operand 0 is not a valid register. This means the variable is a
+      // simple constant, or is described by a complex expression.
+      // FIXME: Find a way to represent constant variables, since they are
+      // relatively common.
+      unsigned Reg =
+          DVInst->getOperand(0).isReg() ? DVInst->getOperand(0).getReg() : 0;
+      if (Reg == 0)
+        continue;
+
+      // Handle the two cases we can handle: indirect in memory and in register.
+      unsigned CVReg = TRI->getCodeViewRegNum(Reg);
+      {
+        LocalVarDefRange DR;
+        DR.CVRegister = CVReg;
+        DR.InMemory = InMemory;
+        DR.DataOffset = Offset;
+        DR.IsSubfield = IsSubfield;
+        DR.StructOffset = StructOffset;
+
+        if (Var.DefRanges.empty() ||
+            Var.DefRanges.back().isDifferentLocation(DR)) {
+          Var.DefRanges.emplace_back(std::move(DR));
+        }
+      }
+
+      // Compute the label range.
+      const MCSymbol *Begin = getLabelBeforeInsn(Range.first);
+      const MCSymbol *End = getLabelAfterInsn(Range.second);
+      if (!End) {
+        // This range is valid until the next overlapping bitpiece. In the
+        // common case, ranges will not be bitpieces, so they will overlap.
+        auto J = std::next(I);
+        while (J != E &&
+               !fragmentsOverlap(DIExpr, J->first->getDebugExpression()))
+          ++J;
+        if (J != E)
+          End = getLabelBeforeInsn(J->first);
+        else
+          End = Asm->getFunctionEnd();
+      }
+
+      // If the last range end is our begin, just extend the last range.
+      // Otherwise make a new range.
+      SmallVectorImpl<std::pair<const MCSymbol *, const MCSymbol *>> &Ranges =
+          Var.DefRanges.back().Ranges;
+      if (!Ranges.empty() && Ranges.back().second == Begin)
+        Ranges.back().second = End;
+      else
+        Ranges.emplace_back(Begin, End);
+
+      // FIXME: Do more range combining.
+    }
+
     recordLocalVariable(std::move(Var), InlinedAt);
   }
 }
@@ -1995,16 +1987,6 @@ TypeIndex CodeViewDebug::getTypeIndex(DITypeRef TypeRef, DITypeRef ClassTyRef) {
   return recordTypeIndexForDINode(Ty, TI, ClassTy);
 }
 
-TypeIndex CodeViewDebug::getTypeIndexForReferenceTo(DITypeRef TypeRef) {
-  DIType *Ty = TypeRef.resolve();
-  PointerRecord PR(getTypeIndex(Ty),
-                   getPointerSizeInBytes() == 8 ? PointerKind::Near64
-                                                : PointerKind::Near32,
-                   PointerMode::LValueReference, PointerOptions::None,
-                   Ty->getSizeInBits() / 8);
-  return TypeTable.writeKnownType(PR);
-}
-
 TypeIndex CodeViewDebug::getCompleteTypeIndex(DITypeRef TypeRef) {
   const DIType *Ty = TypeRef.resolve();
 
@@ -2112,8 +2094,7 @@ void CodeViewDebug::emitLocalVariable(const LocalVariable &Var) {
     Flags |= LocalSymFlags::IsOptimizedOut;
 
   OS.AddComment("TypeIndex");
-  TypeIndex TI = Var.Deref ? getTypeIndexForReferenceTo(Var.DIVar->getType())
-                           : getCompleteTypeIndex(Var.DIVar->getType());
+  TypeIndex TI = getCompleteTypeIndex(Var.DIVar->getType());
   OS.EmitIntValue(TI.getIndex(), 4);
   OS.AddComment("Flags");
   OS.EmitIntValue(static_cast<uint16_t>(Flags), 2);