From 5743416d3e4143974e10ce6db670944e9657efd8 Mon Sep 17 00:00:00 2001
From: Simon Martin <simartin@users.sourceforge.net>
Date: Fri, 16 Aug 2013 23:51:00 +0200
Subject: [PATCH] Ticket #4959: Simplify {in,de}crements of known variables.

---
 lib/tokenize.cpp      | 25 +++++++++++++++++--------
 test/testtokenize.cpp | 20 +++-----------------
 2 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index dd1500d30..e64951156 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -6233,12 +6233,24 @@ bool Tokenizer::simplifyKnownVariables()
                 const std::string structname;
 
                 const Token *valueToken = tok2->tokAt(3);
-                std::string value(tok2->strAt(3));
+                std::string value(tok2->strAt(3)), savedValue = value;
                 const unsigned int valueVarId = 0;
                 const bool valueIsPointer = false;
 
-                Token *scopeStart = tok2->tokAt(6);
-                ret |= simplifyKnownVariablesSimplify(&scopeStart, scopeStart, varid, structname, value, valueIsPointer, valueVarId, valueToken, -1);
+                // Insert a "%var% = %num% ;" at the beginning of the scope as simplifyKnownVariablesSimplify might compute an updated value
+                Token *scopeStart = tok2->tokAt(5);
+                scopeStart->insertToken(tok2->tokAt(1)->str()); scopeStart = scopeStart->next();
+                Token* artificialAssignment = scopeStart;
+                scopeStart->insertToken("="); scopeStart = scopeStart->next();
+                scopeStart->insertToken(valueToken->str()); scopeStart = scopeStart->next();
+                scopeStart->insertToken(";"); scopeStart = scopeStart->next();
+
+                ret |= simplifyKnownVariablesSimplify(&artificialAssignment, tok2->tokAt(6), varid, structname, value, valueIsPointer, valueVarId, valueToken, -1);
+
+                // Remove the artificial assignment if no modification was done
+                if (artificialAssignment->tokAt(2)->str() == savedValue) {
+                    Token::eraseTokens(tok2->tokAt(5), scopeStart->next());
+                }
             }
 
             else if (Token::Match(tok2, "strcpy|sprintf ( %var% , %str% ) ;")) {
@@ -6352,9 +6364,6 @@ bool Tokenizer::simplifyKnownVariablesSimplify(Token **tok2, Token *tok3, unsign
 
     bool ret = false;
 
-    // skip increments and decrements if the given indentlevel is -1
-    const bool skipincdec = (indentlevel == -1);
-
     Token* bailOutFromLoop = 0;
     int indentlevel3 = indentlevel;
     bool ret3 = false;
@@ -6695,7 +6704,7 @@ bool Tokenizer::simplifyKnownVariablesSimplify(Token **tok2, Token *tok3, unsign
             }
         }
 
-        if (!skipincdec && indentlevel == indentlevel3 && Token::Match(tok3->next(), "%varid% ++|--", varid) && MathLib::isInt(value)) {
+        if (indentlevel == indentlevel3 && Token::Match(tok3->next(), "%varid% ++|--", varid) && MathLib::isInt(value)) {
             const std::string op(tok3->strAt(2));
             if (Token::Match(tok3, "[{};] %any% %any% ;")) {
                 tok3->deleteNext(3);
@@ -6713,7 +6722,7 @@ bool Tokenizer::simplifyKnownVariablesSimplify(Token **tok2, Token *tok3, unsign
             ret = true;
         }
 
-        if (!skipincdec && indentlevel == indentlevel3 && Token::Match(tok3->next(), "++|-- %varid%", varid) && MathLib::isInt(value) &&
+        if (indentlevel == indentlevel3 && Token::Match(tok3->next(), "++|-- %varid%", varid) && MathLib::isInt(value) &&
             !Token::Match(tok3->tokAt(3), "[.[]")) {
             incdec(value, tok3->next()->str());
             (*tok2)->tokAt(2)->str(value);
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 0902461e5..3c23180a1 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -2753,12 +2753,6 @@ private:
                             "        buf[x--] = 0;\n"
                             "    }\n"
                             "}";
-        const char current[] = "void f ( int x ) {\n"
-                               "if ( x == 5 ) {\n"
-                               "buf [ x ++ ] = 0 ;\n"
-                               "buf [ x -- ] = 0 ;\n"
-                               "}\n"
-                               "}";
         // Increment and decrements should be computed
         const char expected[] = "void f ( int x ) {\n"
                                 "if ( x == 5 ) {\n"
@@ -2766,7 +2760,7 @@ private:
                                 "buf [ 6 ] = 0 ;\n"
                                 "}\n"
                                 "}";
-        TODO_ASSERT_EQUALS(expected, current, tokenizeAndStringify(code, true, true, Settings::Unspecified, "test.c"));
+        ASSERT_EQUALS(expected, tokenizeAndStringify(code, true, true, Settings::Unspecified, "test.c"));
     }
 
     void simplifyKnownVariablesIfEq3() {
@@ -2777,23 +2771,15 @@ private:
                             "        buf[--x] = 0;\n"
                             "    }\n"
                             "}";
-        const char current[] =  "void f ( int x ) {\n"
-                                "if ( x == 5 ) {\n"
-                                "buf [ ++ x ] = 0 ;\n"
-                                "buf [ ++ x ] = 0 ;\n"
-                                "buf [ -- x ] = 0 ;\n"
-                                "}\n"
-                                "}";
-        // Increment and decrements should be computed
         const char expected[] = "void f ( int x ) {\n"
-                                "if ( x == 5 ) {\n"
+                                "if ( x == 5 ) { "
                                 "x = 6 ;\n"
                                 "buf [ 6 ] = 0 ;\n"
                                 "buf [ 7 ] = 0 ;\n"
                                 "buf [ 6 ] = 0 ;\n"
                                 "}\n"
                                 "}";
-        TODO_ASSERT_EQUALS(expected, current, tokenizeAndStringify(code, true, true, Settings::Unspecified, "test.c"));
+        ASSERT_EQUALS(expected, tokenizeAndStringify(code, true, true, Settings::Unspecified, "test.c"));
     }
 
     void simplifyKnownVariablesBailOutAssign1() {