[lldb] Add SBType::GetByteAlign (#90960)

lldb already mostly(*) tracks this information. This just makes it
available to the SB users.

(*) It does not do that for typedefs right now see llvm.org/pr90958

Author: labath

lldb/include/lldb/API/SBType.h

@@ -150,6 +150,8 @@ class SBType {
 
   uint64_t GetByteSize();
 
+  uint64_t GetByteAlign();
+
   bool IsPointerType();
 
   bool IsReferenceType();

lldb/source/API/SBType.cpp

@@ -25,6 +25,7 @@
 #include "lldb/Utility/Stream.h"
 
 #include "llvm/ADT/APSInt.h"
+#include "llvm/Support/MathExtras.h"
 
 #include <memory>
 #include <optional>
@@ -132,6 +133,18 @@ uint64_t SBType::GetByteSize() {
   return 0;
 }
 
+uint64_t SBType::GetByteAlign() {
+  LLDB_INSTRUMENT_VA(this);
+
+  if (!IsValid())
+    return 0;
+
+  std::optional<uint64_t> bit_align =
+      m_opaque_sp->GetCompilerType(/*prefer_dynamic=*/false)
+          .GetTypeBitAlign(nullptr);
+  return llvm::divideCeil(bit_align.value_or(0), 8);
+}
+
 bool SBType::IsPointerType() {
   LLDB_INSTRUMENT_VA(this);
 

lldb/test/API/python_api/type/TestTypeList.py

@@ -272,3 +272,24 @@ def test(self):
             self.assertTrue(int_enum_uchar)
             self.DebugSBType(int_enum_uchar)
             self.assertEqual(int_enum_uchar.GetName(), "unsigned char")
+
+    def test_GetByteAlign(self):
+        """Exercise SBType::GetByteAlign"""
+        self.build()
+        spec = lldb.SBModuleSpec()
+        spec.SetFileSpec(lldb.SBFileSpec(self.getBuildArtifact()))
+        module = lldb.SBModule(spec)
+        self.assertTrue(module)
+
+        # Invalid types should not crash.
+        self.assertEqual(lldb.SBType().GetByteAlign(), 0)
+
+        # Try a type with natural alignment.
+        void_ptr = module.GetBasicType(lldb.eBasicTypeVoid).GetPointerType()
+        self.assertTrue(void_ptr)
+        # Not exactly guaranteed by the spec, but should be true everywhere we
+        # care about.
+        self.assertEqual(void_ptr.GetByteSize(), void_ptr.GetByteAlign())
+
+        # And an over-aligned type.
+        self.assertEqual(module.FindFirstType("OverAlignedStruct").GetByteAlign(), 128)

lldb/test/API/python_api/type/main.cpp

@@ -50,6 +50,9 @@ enum EnumType {};
 enum class ScopedEnumType {};
 enum class EnumUChar : unsigned char {};
 
+struct alignas(128) OverAlignedStruct {};
+OverAlignedStruct over_aligned_struct;
+
 int main (int argc, char const *argv[])
 {
     Task *task_head = new Task(-1, NULL);