added lazy execution of ValueFlow via DISABLE_VALUEFLOW=2 environment variable

Author: firewave

lib/token.h

@@ -1162,6 +1162,8 @@ class CPPCHECKLIB Token {
     }
 
     const std::list<ValueFlow::Value>& values() const {
+        if (mTokensFrontBack && !mTokensFrontBack->list->isValuesSet())
+            mTokensFrontBack->list->setValues();
         return mImpl->mValues ? *mImpl->mValues : TokenImpl::mEmptyValueList;
     }
 

lib/tokenize.cpp

@@ -2796,6 +2796,7 @@ bool Tokenizer::simplifyTokens1(const std::string &configuration)
         createSymbolDatabase();
     }
 
+    // TODO: this accesses ValueFlow information before it has been generated
     if (mTimerResults) {
         Timer t("Tokenizer::simplifyTokens1::setValueType", mSettings->showtime, mTimerResults);
         mSymbolDatabase->setValueTypeInTokenList(true);
@@ -2819,11 +2820,7 @@ bool Tokenizer::simplifyTokens1(const std::string &configuration)
         }
     }
 
-    // TODO: do not run valueflow if no checks are being performed at all - e.g. unusedFunctions only
-    const char* disableValueflowEnv = std::getenv("DISABLE_VALUEFLOW");
-    const bool doValueFlow = !disableValueflowEnv || (std::strcmp(disableValueflowEnv, "1") != 0);
-
-    if (doValueFlow) {
+    auto setValues = [&](){
         if (mTimerResults) {
             Timer t("Tokenizer::simplifyTokens1::ValueFlow", mSettings->showtime, mTimerResults);
             ValueFlow::setValues(&list, mSymbolDatabase, mErrorLogger, mSettings);
@@ -2832,6 +2829,15 @@ bool Tokenizer::simplifyTokens1(const std::string &configuration)
         }
 
         mSymbolDatabase->setArrayDimensionsUsingValueFlow();
+    };
+
+    const char* disableValueflowEnv = std::getenv("DISABLE_VALUEFLOW");
+    const bool doLazyValueFlow = disableValueflowEnv && (std::strcmp(disableValueflowEnv, "2") == 0);
+    const bool doValueFlow = !disableValueflowEnv || (std::strcmp(disableValueflowEnv, "1") != 0);
+    if (doLazyValueFlow) {
+        list.setValuesFunc(std::move(setValues));
+    } else if (doValueFlow) {
+        setValues();
     }
 
     printDebugOutput(1);

lib/tokenlist.cpp

@@ -49,7 +49,9 @@ TokenList::TokenList(const Settings* settings) :
     mTokensFrontBack(),
     mSettings(settings),
     mIsC(false),
-    mIsCpp(false)
+    mIsCpp(false),
+    mValuesSet(false),
+    mInSetValues(false)
 {
     mTokensFrontBack.list = this;
     mKeywords.insert("asm");

lib/tokenlist.h

@@ -25,6 +25,7 @@
 
 #include <cstddef>
 #include <iosfwd>
+#include <functional>
 #include <string>
 #include <unordered_set>
 #include <vector>
@@ -207,6 +208,23 @@ class CPPCHECKLIB TokenList {
 
     bool isKeyword(const std::string &str) const;
 
+    void setValuesFunc(std::function<void()> f) {
+        mValuesFunc = std::move(f);
+    }
+
+    void setValues() const {
+        if (!mInSetValues && !mValuesSet && mValuesFunc) {
+            mInSetValues = true;
+            mValuesFunc();
+            mValuesSet = true;
+            mInSetValues = false;
+        }
+    }
+
+    bool isValuesSet() const {
+        return mValuesSet;
+    }
+
 private:
     void determineCppC();
 
@@ -227,6 +245,10 @@ class CPPCHECKLIB TokenList {
     /** File is known to be C/C++ code */
     bool mIsC;
     bool mIsCpp;
+
+    std::function<void()> mValuesFunc;
+    mutable bool mValuesSet;
+    mutable bool mInSetValues;
 };
 
 /// @}