DebugInfo: Gut DIExpression

Completely gut `DIExpression`, turning it into a simple wrapper around
`MDExpression *`.  There are two bits of magic left:

  - It's constructed from `const MDExpression*` but convertible to
    `MDExpression*`.
  - It's default-constructed to `nullptr`.

Otherwise, it should behave quite like a raw pointer.  Once I've done
the same to the rest of the `DIDescriptor` subclasses, I'll come back to
delete them entirely (and update call sites as necessary to deal with
the missing magic).

llvm-svn: 234832

2 files changed, 5 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index cecd29b1341..e8310d7f53e 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -4191,14 +4191,14 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
       // Create a piece expression describing the new partition or reuse AI's
       // expression if there is only one partition.
       DIExpression PieceExpr = Expr;
-      if (IsSplit || Expr.isBitPiece()) {
+      if (IsSplit || Expr->isBitPiece()) {
         // If this alloca is already a scalar replacement of a larger aggregate,
         // Piece.Offset describes the offset inside the scalar.
-        uint64_t Offset = Expr.isBitPiece() ? Expr.getBitPieceOffset() : 0;
+        uint64_t Offset = Expr->isBitPiece() ? Expr->getBitPieceOffset() : 0;
         uint64_t Start = Offset + Piece.Offset;
         uint64_t Size = Piece.Size;
-        if (Expr.isBitPiece()) {
-          uint64_t AbsEnd = Expr.getBitPieceOffset() + Expr.getBitPieceSize();
+        if (Expr->isBitPiece()) {
+          uint64_t AbsEnd = Expr->getBitPieceOffset() + Expr->getBitPieceSize();
           if (Start >= AbsEnd)
             // No need to describe a SROAed padding.
             continue;
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index cba77452061..a8f4c211009 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1121,8 +1121,7 @@ bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
     SmallVector<uint64_t, 4> NewDIExpr;
     NewDIExpr.push_back(dwarf::DW_OP_deref);
     if (DIExpr)
-      for (unsigned i = 0, n = DIExpr.getNumElements(); i < n; ++i)
-        NewDIExpr.push_back(DIExpr.getElement(i));
+      NewDIExpr.append(DIExpr->elements_begin(), DIExpr->elements_end());
     DIExpr = Builder.createExpression(NewDIExpr);
   }