From 11e32ff445ccc5b13f0321217d31771ce75cf70d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Tue, 12 Mar 2019 18:53:58 +0100
Subject: [PATCH] ValueFlow: Handle compound assignments in execute()

---
 lib/valueflow.cpp      | 35 +++++++++++++++++++++++++++++++----
 test/testvalueflow.cpp |  7 +++++++
 2 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index fb3a60559..453d6dcf0 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -3766,12 +3766,39 @@ static void execute(const Token *expr,
             *result = result1 != result2;
     }
 
-    else if (expr->str() == "=") {
+    else if (expr->isAssignmentOp()) {
         execute(expr->astOperand2(), programMemory, result, error);
-        if (!*error && expr->astOperand1() && expr->astOperand1()->varId())
-            programMemory->setIntValue(expr->astOperand1()->varId(), *result);
-        else
+        if (!expr->astOperand1() || !expr->astOperand1()->varId())
             *error = true;
+        if (*error)
+            return;
+
+        if (expr->str() == "=") {
+            programMemory->setIntValue(expr->astOperand1()->varId(), *result);
+            return;
+        }
+
+        long long intValue;
+        if (!programMemory->getIntValue(expr->astOperand1()->varId(), &intValue)) {
+            *error = true;
+            return;
+        }
+        if (expr->str() == "+=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue + *result);
+        else if (expr->str() == "-=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue - *result);
+        else if (expr->str() == "*=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue * *result);
+        else if (expr->str() == "/=" && *result != 0)
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue / *result);
+        else if (expr->str() == "%=" && *result != 0)
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue % *result);
+        else if (expr->str() == "&=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue & *result);
+        else if (expr->str() == "|=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue | *result);
+        else if (expr->str() == "^=")
+            programMemory->setIntValue(expr->astOperand1()->varId(), intValue ^ *result);
     }
 
     else if (Token::Match(expr, "++|--")) {
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 22b0a4690..73caed889 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -2558,6 +2558,13 @@ private:
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 3U, 9));
 
+        code = "void f() {\n"
+               "    for (int x = 0; x < 5; x += 2)\n"
+               "        a[x] = 0;\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfX(code, 3U, 0));
+        ASSERT_EQUALS(true, testValueOfX(code, 3U, 4));
+
         code = "void f() {\n"
                "    for (int x = 0; x < 10; x = x + 2)\n"
                "        a[x] = 0;\n"