Utils: Fix long small string

We used only 6 bit to save the short size but for SmallString with a size
over 64 it is not enough. So we have now to use a uint16 instead of a
uint8 if the size if over 64.

Change-Id: I53558e492b6cb40b739b23a8af83d192a2e11bd2
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/libs/clangbackendipc/clangbackendipc_global.h

@@ -55,7 +55,7 @@ namespace Utils {
 template <uint Size>
 class BasicSmallString;
 using SmallString = BasicSmallString<31>;
-using PathString = BasicSmallString<191>;
+using PathString = BasicSmallString<190>;
 }
 
 namespace ClangBackEnd {

src/libs/utils/smallstring.h

@@ -65,6 +65,11 @@ public:
     using const_reverse_iterator = std::reverse_iterator<const_iterator>;
     using size_type = std::size_t;
 
+    static_assert(Size < 64
+                ? sizeof(Internal::StringDataLayout<Size>) == Size + 1
+                : sizeof(Internal::StringDataLayout<Size>) == Size + 2,
+                  "Size is wrong");
+
     BasicSmallString() noexcept
         : m_data(Internal::StringDataLayout<Size>())
     {
@@ -498,7 +503,7 @@ public:
     constexpr static
     size_type shortStringCapacity() noexcept
     {
-        return BasicSmallStringLiteral<Size>::shortStringCapacity();
+        return Internal::StringDataLayout<Size>::shortStringCapacity();
     }
 
     size_type optimalCapacity(const size_type size)
@@ -897,6 +902,6 @@ std::vector<Type> clone(const std::vector<Type> &vector)
 }
 
 using SmallString = BasicSmallString<31>;
-using PathString = BasicSmallString<191>;
+using PathString = BasicSmallString<190>;
 
 } // namespace Utils

src/libs/utils/smallstringlayout.h

@@ -28,6 +28,7 @@
 #include <QtGlobal>
 
 #include <cstdint>
+#include <type_traits>
 
 #ifdef Q_CC_MSVC
 #   define ALIGNAS_16
@@ -41,7 +42,19 @@ namespace Internal {
 
 using size_type = std::size_t;
 
-template <uint MaximumShortStringDataAreaSize>
+template<bool Bool>
+struct block_type
+{
+    using type = uint8_t;
+};
+
+template<>
+struct block_type<false> {
+    using type = uint16_t;
+};
+
+template <uint MaximumShortStringDataAreaSize,
+          typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
 struct AllocatedLayout {
     struct Data {
         char *pointer;
@@ -49,12 +62,13 @@ struct AllocatedLayout {
         size_type capacity;
     } data;
     char dummy[MaximumShortStringDataAreaSize - sizeof(Data)];
-    std::uint8_t shortStringSize: 6;
+    BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
-    std::uint8_t isReadOnlyReference : 1;
+    BlockType isReadOnlyReference : 1;
-    std::uint8_t isReference : 1;
+    BlockType isReference : 1;
 };
 
-template <uint MaximumShortStringDataAreaSize>
+template <uint MaximumShortStringDataAreaSize,
+          typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
 struct ReferenceLayout {
     struct Data {
         const char *pointer;
@@ -62,23 +76,28 @@ struct ReferenceLayout {
         size_type capacity;
     } data;
     char dummy[MaximumShortStringDataAreaSize - sizeof(Data)];
-    std::uint8_t shortStringSize: 6;
+    BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
-    std::uint8_t isReadOnlyReference : 1;
+    BlockType isReadOnlyReference : 1;
-    std::uint8_t isReference : 1;
+    BlockType isReference : 1;
 };
 
-template <uint MaximumShortStringDataAreaSize>
+template <uint MaximumShortStringDataAreaSize,
+          typename BlockType = typename block_type<(MaximumShortStringDataAreaSize < 64)>::type>
 struct ShortStringLayout {
     char string[MaximumShortStringDataAreaSize];
-    std::uint8_t shortStringSize: 6;
+    BlockType shortStringSize : (sizeof(BlockType) * 8) - 2;
-    std::uint8_t isReadOnlyReference : 1;
+    BlockType isReadOnlyReference : 1;
-    std::uint8_t isReference : 1;
+    BlockType isReference : 1;
 };
 
 template <uint MaximumShortStringDataAreaSize>
 struct ALIGNAS_16 StringDataLayout {
     static_assert( MaximumShortStringDataAreaSize >= 15, "Size must be greater equal than 15 bytes!");
-    static_assert(((MaximumShortStringDataAreaSize + 1) % 16) == 0, "Size + 1 must be dividable by 16!");
+    static_assert(MaximumShortStringDataAreaSize < 64
+                ? ((MaximumShortStringDataAreaSize + 1) % 16) == 0
+                : ((MaximumShortStringDataAreaSize + 2) % 16) == 0,
+                  "Size + 1 must be dividable by 16 if under 64 and Size + 2 must be dividable by 16 if over 64!");
+
     StringDataLayout() noexcept = default;
 
     constexpr StringDataLayout(const char *string,
@@ -117,6 +136,14 @@ struct ALIGNAS_16 StringDataLayout {
 #endif
     }
 
+    constexpr static
+    size_type shortStringCapacity() noexcept
+    {
+        return MaximumShortStringDataAreaSize < 64
+             ? MaximumShortStringDataAreaSize - 1
+             : MaximumShortStringDataAreaSize - 2;
+    }
+
     union {
         AllocatedLayout<MaximumShortStringDataAreaSize> allocated;
         ReferenceLayout<MaximumShortStringDataAreaSize> reference;

src/libs/utils/smallstringliteral.h

@@ -89,7 +89,7 @@ public:
     constexpr static
     size_type shortStringCapacity() noexcept
     {
-        return sizeof(Internal::ShortStringLayout<Size>) - 2;
+        return Internal::StringDataLayout<Size>::shortStringCapacity();
     }
 
     bool isShortString() const noexcept

src/libs/utils/smallstringvector.h

@@ -154,5 +154,5 @@ private:
 };
 
 using SmallStringVector = BasicSmallStringVector<31>;
-using PathStringVector = BasicSmallStringVector<191>;
+using PathStringVector = BasicSmallStringVector<190>;
 } // namespace Utils;

src/tools/clangpchmanagerbackend/source/clangpchmanagerbackend_global.h

@@ -44,7 +44,7 @@ namespace Utils {
 template <uint Size>
 class BasicSmallString;
 using SmallString = BasicSmallString<31>;
-using PathString = BasicSmallString<191>;
+using PathString = BasicSmallString<190>;
 }
 
 namespace ClangBackEnd {

tests/unit/unittest/smallstring-test.cpp

@@ -33,6 +33,7 @@
 
 using namespace ::testing;
 
+using Utils::PathString;
 using Utils::SmallString;
 using Utils::SmallStringLiteral;
 using Utils::SmallStringView;
@@ -445,6 +446,15 @@ TEST(SmallString, SizeShortSmallString)
     ASSERT_THAT(size, 4);
 }
 
+TEST(SmallString, SizeShortPathString)
+{
+    SmallString shortPath("very very very very very very very very very very very long path which fits in the short memory");
+
+    auto size = shortPath.size();
+
+    ASSERT_THAT(size, 95);
+}
+
 TEST(SmallString, SizeLongSmallString)
 {
     auto longText = SmallString::fromUtf8("very very very very very very very very very very very long string");