From 2a640a59c22db86bae132ae007d052e4b612c849 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Sat, 16 Nov 2013 17:30:04 +0100
Subject: [PATCH] Tokenizer: Improved handling of pointer aliases. This fixes
 some false negatives.

---
 lib/tokenize.cpp      | 13 ++++++++++++-
 test/testtokenize.cpp |  7 +++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index bda1a3df4..6ce67b1ac 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -6730,6 +6730,17 @@ bool Tokenizer::simplifyKnownVariablesSimplify(Token **tok2, Token *tok3, unsign
             ret = true;
         }
 
+        // pointer alias used in condition..
+        if (Token::Match(valueToken,"& %var% ;") && Token::Match(tok3, ("( * " + structname + " %varid% %cop%").c_str(), varid)) {
+            tok3->deleteNext();
+            if (!structname.empty())
+                tok3->deleteNext(2);
+            tok3 = tok3->next();
+            tok3->str(value);
+            tok3->varId(valueVarId);
+            ret = true;
+        }
+
         // Delete pointer alias
         if (pointeralias && tok3->str() == "delete" &&
             (Token::Match(tok3, "delete %varid% ;", varid) ||
@@ -6818,7 +6829,7 @@ bool Tokenizer::simplifyKnownVariablesSimplify(Token **tok2, Token *tok3, unsign
                 ret = true;
             tok3->str(value);
             tok3->varId(valueVarId);
-            if (tok3->previous()->str() == "*" && valueIsPointer) {
+            if (tok3->previous()->str() == "*" && (valueIsPointer || Token::Match(valueToken, "& %var% ;"))) {
                 tok3 = tok3->previous();
                 tok3->deleteThis();
                 ret = true;
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index dcaf8b6e1..87f84ad2d 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -181,6 +181,7 @@ private:
         TEST_CASE(simplifyKnownVariables52);    // #4728 "= x %cop%"
         TEST_CASE(simplifyKnownVariables53);    // references
         TEST_CASE(simplifyKnownVariables54);    // #4913 'x' is not 0 after *--x=0;
+        TEST_CASE(simplifyKnownVariables55);    // pointer alias
         TEST_CASE(simplifyKnownVariablesIfEq1); // if (a==5) => a is 5 in the block
         TEST_CASE(simplifyKnownVariablesIfEq2); // if (a==5) { buf[a++] = 0; }
         TEST_CASE(simplifyKnownVariablesIfEq3); // #4708 - if (a==5) { buf[--a] = 0; }
@@ -2824,6 +2825,12 @@ private:
         ASSERT_EQUALS("void f ( int * p ) { * -- p = 0 ; * p = 0 ; }", tokenizeAndStringify("void f(int*p) { *--p=0; *p=0; }", true));
     }
 
+    void simplifyKnownVariables55() { // pointer alias
+        ASSERT_EQUALS("void f ( ) { int a ; if ( a > 0 ) { } }", tokenizeAndStringify("void f() { int a; int *p=&a; if (*p>0) {} }", true));
+        ASSERT_EQUALS("void f ( ) { int a ; struct AB ab ; ab . a = & a ; if ( a > 0 ) { } }", tokenizeAndStringify("void f() { int a; struct AB ab; ab.a = &a; if (*ab.a>0) {} }", true));
+        ASSERT_EQUALS("void f ( ) { int a ; if ( x > a ) { } }", tokenizeAndStringify("void f() { int a; int *p=&a; if (x>*p) {} }", true));
+    }
+
     void simplifyKnownVariablesIfEq1() {
         const char code[] = "void f(int x) {\n"
                             "    if (x==5) {\n"