Fix #12182 (speedup valueFlow by only running valueFlowNumber once) (#5678)

Author: danmar

lib/valueflow.cpp

@@ -1042,6 +1042,16 @@ static void setTokenValue(Token* tok,
         }
     }
 
+    // C++ init
+    else if (parent->str() == "{" && Token::simpleMatch(parent->previous(), "= {") && Token::simpleMatch(parent->link(), "} ;")) {
+        const Token* lhs = parent->previous()->astOperand1();
+        if (lhs && lhs->valueType()) {
+            if (lhs->valueType()->isIntegral() || lhs->valueType()->isFloat() || (lhs->valueType()->pointer > 0 && value.isIntValue())) {
+                setTokenValue(parent, value, settings);
+            }
+        }
+    }
+
     else if (Token::Match(parent, ":: %name%") && parent->astOperand2() == tok) {
         setTokenValue(parent, value, settings);
     }
@@ -1335,16 +1345,12 @@ static Token * valueFlowSetConstantValue(Token *tok, const Settings *settings, b
         if (!tok->isTemplateArg())
             value.setKnown();
         setTokenValue(tok->next(), std::move(value), settings);
-    } else if (Token::Match(tok, "%name% = {") && tok->variable() &&
-               (tok->variable()->isPointer() || (tok->variable()->valueType() && tok->variable()->valueType()->isIntegral()))) {
-        if (Token::simpleMatch(tok->tokAt(3), "}")) {
+    } else if (Token::simpleMatch(tok, "= { } ;")) {
+        const Token* lhs = tok->astOperand1();
+        if (lhs && lhs->valueType() && (lhs->valueType()->isIntegral() || lhs->valueType()->pointer > 0)) {
             ValueFlow::Value value(0);
             value.setKnown();
-            setTokenValue(tok->tokAt(2), std::move(value), settings);
-        } else if (tok->tokAt(2)->astOperand1() && tok->tokAt(2)->astOperand1()->hasKnownIntValue()) {
-            ValueFlow::Value value(tok->tokAt(2)->astOperand1()->getKnownIntValue());
-            value.setKnown();
-            setTokenValue(tok->tokAt(2), std::move(value), settings);
+            setTokenValue(tok->next(), std::move(value), settings);
         }
     }
     return tok->next();
@@ -9448,7 +9454,6 @@ void ValueFlow::setValues(TokenList& tokenlist,
         VFA(valueFlowUnknownFunctionReturn(tokenlist, settings)),
         VFA(valueFlowGlobalConstVar(tokenlist, settings)),
         VFA(valueFlowEnumValue(symboldatabase, settings)),
-        VFA(valueFlowNumber(tokenlist, settings)),
         VFA(valueFlowGlobalStaticVar(tokenlist, settings)),
         VFA(valueFlowPointerAlias(tokenlist, settings)),
         VFA(valueFlowLifetime(tokenlist, errorLogger, settings)),

test/cli/test-other.py

@@ -191,6 +191,77 @@ def test_slow_long_line(tmpdir):
     cppcheck([filename]) # should not take more than ~1 second
 
 
+@pytest.mark.timeout(60)
+def test_slow_large_constant_expression(tmpdir):
+    # 12182
+    filename = os.path.join(tmpdir, 'hang.c')
+    with open(filename, 'wt') as f:
+        f.write("""
+#define FLAG1 0
+#define FLAG2 0
+#define FLAG3 0
+#define FLAG4 0
+#define FLAG5 0
+#define FLAG6 0
+#define FLAG7 0
+#define FLAG8 0
+#define FLAG9 0
+#define FLAG10 0
+#define FLAG11 0
+#define FLAG12 0
+#define FLAG13 0
+#define FLAG14 0
+#define FLAG15 0
+#define FLAG16 0
+#define FLAG17 0
+#define FLAG18 0
+#define FLAG19 0
+#define FLAG20 0
+#define FLAG21 0
+#define FLAG22 0
+#define FLAG23 0
+#define FLAG24 0
+
+#define maxval(x, y) ((x) > (y) ? (x) : (y))
+
+#define E_SAMPLE_SIZE   maxval( FLAG1,                \
+                                  maxval( FLAG2,      \
+                                  maxval( FLAG3,      \
+                                  maxval( FLAG4,      \
+                                  maxval( FLAG5,      \
+                                  maxval( FLAG6,      \
+                                  maxval( FLAG7,      \
+                                  maxval( FLAG8,      \
+                                  maxval( FLAG9,      \
+                                  maxval( FLAG10,     \
+                                  maxval( FLAG11,     \
+                                  maxval( FLAG12,     \
+                                  maxval( FLAG13,     \
+                                  maxval( FLAG14,     \
+                                  FLAG15 ))))))))))))))
+
+#define SAMPLE_SIZE       maxval( E_SAMPLE_SIZE,      \
+                                  maxval( sizeof(st), \
+                                  maxval( FLAG16,     \
+                                  maxval( FLAG17,     \
+                                  maxval( FLAG18,     \
+                                  maxval( FLAG19,     \
+                                  maxval( FLAG20,     \
+                                  maxval( FLAG21,     \
+                                  maxval( FLAG22,     \
+                                  maxval( FLAG23,     \
+                                          FLAG24 ))))))))))
+
+typedef struct {
+    int n;
+} st;
+
+x = SAMPLE_SIZE;
+        """)
+
+    cppcheck([filename])
+
+
 def test_execute_addon_failure(tmpdir):
     test_file = os.path.join(tmpdir, 'test.cpp')
     with open(test_file, 'wt') as f: