[Lldb-commits] [lldb] [lldb] Fix Scalar::GetData for non-multiple-of-8-bits values (PR #90846)

[Pavel Labath via lldb-commits]

https://github.com/labath created https://github.com/llvm/llvm-project/pull/90846

It was aligning the byte size down. Now it aligns up. This manifested itself as SBTypeStaticField::GetConstantValue returning a zero-sized value for `bool` fields (because clang represents bool as a 1-bit value).

I've changed the code for float Scalars as well, although I'm not aware of floating point values that are not multiples of 8 bits.

>From 7336344b98881a5158d9d4d72af5c51ebd1e74e2 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Thu, 2 May 2024 10:49:13 +0000
Subject: [PATCH] [lldb] Fix Scalar::GetData for non-multiple-of-8-bits values

It was aligning the byte size down. Now it aligns up. This manifested
itself as SBTypeStaticField::GetConstantValue returning a zero-sized
value for `bool` fields (because clang represents bool as a 1-bit value).

I've changed the code for float Scalars as well, although I'm not aware
of floating point values that are not multiples of 8 bits.
---
 lldb/source/Utility/Scalar.cpp                |  4 +--
 lldb/test/API/python_api/type/TestTypeList.py | 11 +++++++
 lldb/test/API/python_api/type/main.cpp        |  1 +
 lldb/unittests/Utility/ScalarTest.cpp         | 30 +++++++++++++++++++
 4 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/lldb/source/Utility/Scalar.cpp b/lldb/source/Utility/Scalar.cpp
index e94fd459623665..c70c5e10799187 100644
--- a/lldb/source/Utility/Scalar.cpp
+++ b/lldb/source/Utility/Scalar.cpp
@@ -134,9 +134,9 @@ size_t Scalar::GetByteSize() const {
   case e_void:
     break;
   case e_int:
-    return (m_integer.getBitWidth() / 8);
+    return (m_integer.getBitWidth() + 7) / 8;
   case e_float:
-    return m_float.bitcastToAPInt().getBitWidth() / 8;
+    return (m_float.bitcastToAPInt().getBitWidth() + 7) / 8;
   }
   return 0;
 }
diff --git a/lldb/test/API/python_api/type/TestTypeList.py b/lldb/test/API/python_api/type/TestTypeList.py
index 81c44f7a39d61a..4dbfb06f8fc58c 100644
--- a/lldb/test/API/python_api/type/TestTypeList.py
+++ b/lldb/test/API/python_api/type/TestTypeList.py
@@ -52,6 +52,17 @@ def _find_static_field_in_Task_pointer(self, task_pointer):
         self.DebugSBValue(value)
         self.assertEqual(value.GetValueAsSigned(), 47)
 
+        static_constexpr_bool_field = task_type.GetStaticFieldWithName(
+            "static_constexpr_bool_field"
+        )
+        self.assertTrue(static_constexpr_bool_field)
+        self.assertEqual(static_constexpr_bool_field.GetName(), "static_constexpr_bool_field")
+        self.assertEqual(static_constexpr_bool_field.GetType().GetName(), "const bool")
+
+        value = static_constexpr_bool_field.GetConstantValue(self.target())
+        self.DebugSBValue(value)
+        self.assertEqual(value.GetValueAsUnsigned(), 1)
+
         static_mutable_field = task_type.GetStaticFieldWithName("static_mutable_field")
         self.assertTrue(static_mutable_field)
         self.assertEqual(static_mutable_field.GetName(), "static_mutable_field")
diff --git a/lldb/test/API/python_api/type/main.cpp b/lldb/test/API/python_api/type/main.cpp
index c86644d918279a..7384a3d8da16fb 100644
--- a/lldb/test/API/python_api/type/main.cpp
+++ b/lldb/test/API/python_api/type/main.cpp
@@ -28,6 +28,7 @@ class Task {
     union U {
     } u;
     static constexpr long static_constexpr_field = 47;
+    static constexpr bool static_constexpr_bool_field = true;
     static int static_mutable_field;
     Task(int i, Task *n):
         id(i),
diff --git a/lldb/unittests/Utility/ScalarTest.cpp b/lldb/unittests/Utility/ScalarTest.cpp
index 8d957d16593ee7..500cb8bb2286e0 100644
--- a/lldb/unittests/Utility/ScalarTest.cpp
+++ b/lldb/unittests/Utility/ScalarTest.cpp
@@ -13,8 +13,11 @@
 #include "lldb/Utility/Scalar.h"
 #include "lldb/Utility/Status.h"
 #include "lldb/Utility/StreamString.h"
+#include "lldb/lldb-enumerations.h"
+#include "llvm/ADT/APSInt.h"
 #include "llvm/Testing/Support/Error.h"
 
+#include <algorithm>
 #include <cmath>
 
 using namespace lldb_private;
@@ -163,6 +166,33 @@ TEST(ScalarTest, GetBytes) {
   ASSERT_EQ(0, memcmp(f, Storage, sizeof(f)));
 }
 
+TEST(ScalarTest, GetData) {
+  auto get_data = [](llvm::APSInt v) {
+    DataExtractor data;
+    Scalar(v).GetData(data);
+    return data.GetData().vec();
+  };
+
+  auto vec = [](std::initializer_list<uint8_t> l) {
+    std::vector<uint8_t> v(l.begin(), l.end());
+    if (endian::InlHostByteOrder() == lldb::eByteOrderLittle)
+      std::reverse(v.begin(), v.end());
+    return v;
+  };
+
+  EXPECT_THAT(
+      get_data(llvm::APSInt::getMaxValue(/*numBits=*/1, /*Unsigned=*/true)),
+      vec({0x01}));
+
+  EXPECT_THAT(
+      get_data(llvm::APSInt::getMaxValue(/*numBits=*/8, /*Unsigned=*/true)),
+      vec({0xff}));
+
+  EXPECT_THAT(
+      get_data(llvm::APSInt::getMaxValue(/*numBits=*/9, /*Unsigned=*/true)),
+      vec({0x01, 0xff}));
+}
+
 TEST(ScalarTest, SetValueFromData) {
   uint8_t a[] = {1, 2, 3, 4};
   Scalar s;