[lldb] Add a positive test for `getelementptr` constant args

[werat]

Summary

The IR interpreter supports const operands to the GetElementPtr IR
instruction, so it should be able to evaluate expression without JIT.

Follow up to https://reviews.llvm.org/D113498

[shafik]

Thank you! LGTM

lldb/test/API/lang/cpp/static_members/TestCPPStaticMembers.py

def test_no_crash_in_IR_arithmetic(self):
         self.assertTrue(value.GetError().Fail())
         self.assertIn(
             "Can't evaluate the expression without a running target",
             value.GetError().GetCString())
 
         # Evaluating the expression via JIT should work fine.
         value = self.target().EvaluateExpression(expr)
         self.assertSuccess(value.GetError())
+
+    # We fail to lookup static members on Windows.
+    @expectedFailureAll(oslist=["windows"])
+    def test_IR_interpreter_can_handle_getelementptr_constants_args(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "// stop in main", lldb.SBFileSpec("main.cpp"))
+
+        # This expression contains the following IR code:
+        # ... getelementptr inbounds [2 x i32], [2 x i32]* %4, i64 0, i64 0
+        expr = "arr[0]"
+
+        # The IR interpreter supports const operands to the `GetElementPtr` IR
+        # instruction, so it should be able to evaluate expression without JIT.
+        opts = lldb.SBExpressionOptions()
+        opts.SetAllowJIT(False)
+        value = self.target().EvaluateExpression(expr, opts)
+        self.assertSuccess(value.GetError())

lldb/test/API/lang/cpp/static_members/main.cpp

 
 long A::s_b = 2;
 int A::s_c = 3;
 
 int main() {
   A my_a;
   my_a.m_a = 1;
 
+  int arr[2]{0};
+
   my_a.access(); // stop in main
   return 0;
 }