Fix read-of-uninitialized introduced in r253277 exposed on some buildbots

[oota-llvm.git] / include / llvm / ADT / StringSwitch.h

diff --git a/include/llvm/ADT/StringSwitch.h b/include/llvm/ADT/StringSwitch.h
index 7ac0f60f287c5105eaef871e35f70ace3fed6142..42b0fc4bc441f68b2d55e0b70e4e63b6fec0fb29 100644 (file)
--- a/include/llvm/ADT/StringSwitch.h
+++ b/include/llvm/ADT/StringSwitch.h
@@ -14,6 +14,7 @@
 #define LLVM_ADT_STRINGSWITCH_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <cstring>
 
@@ -38,70 +39,125 @@ namespace llvm {
 ///   .Cases("violet", "purple", Violet)
 ///   .Default(UnknownColor);
 /// \endcode
-template<typename T>
+template<typename T, typename R = T>
 class StringSwitch {
   /// \brief The string we are matching.
   StringRef Str;
 
-  /// \brief The result of this switch statement, once known.
-  T Result;
-
-  /// \brief Set true when the result of this switch is already known; in this
-  /// case, Result is valid.
-  bool ResultKnown;
+  /// \brief The pointer to the result of this switch statement, once known,
+  /// null before that.
+  const T *Result;
 
 public:
-  explicit StringSwitch(StringRef Str)
-  : Str(Str), ResultKnown(false) { }
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  explicit StringSwitch(StringRef S)
+  : Str(S), Result(nullptr) { }
 
   template<unsigned N>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Case(const char (&S)[N], const T& Value) {
-    if (!ResultKnown && N-1 == Str.size() &&
+    if (!Result && N-1 == Str.size() &&
         (std::memcmp(S, Str.data(), N-1) == 0)) {
-      Result = Value;
-      ResultKnown = true;
+      Result = &Value;
+    }
+
+    return *this;
+  }
+
+  template<unsigned N>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch& EndsWith(const char (&S)[N], const T &Value) {
+    if (!Result && Str.size() >= N-1 &&
+        std::memcmp(S, Str.data() + Str.size() + 1 - N, N-1) == 0) {
+      Result = &Value;
+    }
+
+    return *this;
+  }
+
+  template<unsigned N>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  StringSwitch& StartsWith(const char (&S)[N], const T &Value) {
+    if (!Result && Str.size() >= N-1 &&
+        std::memcmp(S, Str.data(), N-1) == 0) {
+      Result = &Value;
     }
 
     return *this;
   }
 
   template<unsigned N0, unsigned N1>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
                       const T& Value) {
-    return Case(S0, Value).Case(S1, Value);
+    if (!Result && (
+        (N0-1 == Str.size() && std::memcmp(S0, Str.data(), N0-1) == 0) ||
+        (N1-1 == Str.size() && std::memcmp(S1, Str.data(), N1-1) == 0))) {
+      Result = &Value;
+    }
+
+    return *this;
   }
 
   template<unsigned N0, unsigned N1, unsigned N2>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
                       const char (&S2)[N2], const T& Value) {
-    return Case(S0, Value).Case(S1, Value).Case(S2, Value);
+    if (!Result && (
+        (N0-1 == Str.size() && std::memcmp(S0, Str.data(), N0-1) == 0) ||
+        (N1-1 == Str.size() && std::memcmp(S1, Str.data(), N1-1) == 0) ||
+        (N2-1 == Str.size() && std::memcmp(S2, Str.data(), N2-1) == 0))) {
+      Result = &Value;
+    }
+
+    return *this;
   }
 
   template<unsigned N0, unsigned N1, unsigned N2, unsigned N3>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
                       const char (&S2)[N2], const char (&S3)[N3],
                       const T& Value) {
-    return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value);
+    if (!Result && (
+        (N0-1 == Str.size() && std::memcmp(S0, Str.data(), N0-1) == 0) ||
+        (N1-1 == Str.size() && std::memcmp(S1, Str.data(), N1-1) == 0) ||
+        (N2-1 == Str.size() && std::memcmp(S2, Str.data(), N2-1) == 0) ||
+        (N3-1 == Str.size() && std::memcmp(S3, Str.data(), N3-1) == 0))) {
+      Result = &Value;
+    }
+
+    return *this;
   }
 
   template<unsigned N0, unsigned N1, unsigned N2, unsigned N3, unsigned N4>
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
   StringSwitch& Cases(const char (&S0)[N0], const char (&S1)[N1],
                       const char (&S2)[N2], const char (&S3)[N3],
                       const char (&S4)[N4], const T& Value) {
-    return Case(S0, Value).Case(S1, Value).Case(S2, Value).Case(S3, Value)
-      .Case(S4, Value);
+    if (!Result && (
+        (N0-1 == Str.size() && std::memcmp(S0, Str.data(), N0-1) == 0) ||
+        (N1-1 == Str.size() && std::memcmp(S1, Str.data(), N1-1) == 0) ||
+        (N2-1 == Str.size() && std::memcmp(S2, Str.data(), N2-1) == 0) ||
+        (N3-1 == Str.size() && std::memcmp(S3, Str.data(), N3-1) == 0) ||
+        (N4-1 == Str.size() && std::memcmp(S4, Str.data(), N4-1) == 0))) {
+      Result = &Value;
+    }
+
+    return *this;
   }
 
-  T Default(const T& Value) {
-    if (ResultKnown)
-      return Result;
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  R Default(const T& Value) const {
+    if (Result)
+      return *Result;
 
     return Value;
   }
 
-  operator T() {
-    assert(ResultKnown && "Fell off the end of a string-switch");
-    return Result;
+  LLVM_ATTRIBUTE_ALWAYS_INLINE
+  operator R() const {
+    assert(Result && "Fell off the end of a string-switch");
+    return *Result;
   }
 };