[DebugInfo] Fix faulty DIExpression::appendToStack assert (#85255)

The appendToStack() function asserts that no DW_OP_stack_value or
DW_OP_LLVM_fragment operations are present in the operations to be
appended. The function did that by iterating over all elements in the
array rather than just the operations, leading it to falsely asserting
on the following input produced by getExt(), since 159 (0x9f) is the
DWARF code for DW_OP_stack_value:

  {dwarf::DW_OP_LLVM_convert, 159, dwarf::DW_ATE_signed}

Fix this by using expr_op iterators.

Author: dstenb

llvm/lib/IR/DebugInfoMetadata.cpp

@@ -1880,11 +1880,12 @@ DIExpression *DIExpression::append(const DIExpression *Expr,
 DIExpression *DIExpression::appendToStack(const DIExpression *Expr,
                                           ArrayRef<uint64_t> Ops) {
   assert(Expr && !Ops.empty() && "Can't append ops to this expression");
-  assert(none_of(Ops,
-                 [](uint64_t Op) {
-                   return Op == dwarf::DW_OP_stack_value ||
-                          Op == dwarf::DW_OP_LLVM_fragment;
-                 }) &&
+  assert(std::none_of(expr_op_iterator(Ops.begin()),
+                      expr_op_iterator(Ops.end()),
+                      [](auto Op) {
+                        return Op.getOp() == dwarf::DW_OP_stack_value ||
+                               Op.getOp() == dwarf::DW_OP_LLVM_fragment;
+                      }) &&
          "Can't append this op");
 
   // Append a DW_OP_deref after Expr's current op list if it's non-empty and

llvm/unittests/IR/MetadataTest.cpp

@@ -3560,6 +3560,27 @@ TEST_F(DIExpressionTest, foldConstant) {
 #undef EXPECT_FOLD_CONST
 }
 
+TEST_F(DIExpressionTest, appendToStackAssert) {
+  DIExpression *Expr = DIExpression::get(Context, {});
+
+  // Verify that the DW_OP_LLVM_convert operands, which have the same values as
+  // DW_OP_stack_value and DW_OP_LLVM_fragment, do not get interpreted as such
+  // operations. This previously triggered an assert.
+  uint64_t FromSize = dwarf::DW_OP_stack_value;
+  uint64_t ToSize = dwarf::DW_OP_LLVM_fragment;
+  uint64_t Ops[] = {
+      dwarf::DW_OP_LLVM_convert, FromSize, dwarf::DW_ATE_signed,
+      dwarf::DW_OP_LLVM_convert, ToSize,   dwarf::DW_ATE_signed,
+  };
+  Expr = DIExpression::appendToStack(Expr, Ops);
+
+  uint64_t Expected[] = {
+      dwarf::DW_OP_LLVM_convert, FromSize, dwarf::DW_ATE_signed,
+      dwarf::DW_OP_LLVM_convert, ToSize,   dwarf::DW_ATE_signed,
+      dwarf::DW_OP_stack_value};
+  EXPECT_EQ(Expr->getElements(), ArrayRef<uint64_t>(Expected));
+}
+
 typedef MetadataTest DIObjCPropertyTest;
 
 TEST_F(DIObjCPropertyTest, get) {