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Fix some false positive in loop forward analysis #2669

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Merged
danmar merged 2 commits into from
Jun 5, 2020
Merged

Fix some false positive in loop forward analysis #2669

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cb04fe5
Fix some false positive in loop forward analysis
Ken-Patrick Jun 1, 2020
5828ee2
Fix style
Ken-Patrick Jun 1, 2020
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13 changes: 11 additions & 2 deletions lib/forwardanalyzer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -220,8 +220,17 @@ struct ForwardTraversal {
return Progress::Break;
}
// Traverse condition after lowering
if (condTok && updateRecursive(condTok) == Progress::Break)
return Progress::Break;
if (condTok) {
if (updateRecursive(condTok) == Progress::Break)
return Progress::Break;

bool checkThen, checkElse;
std::tie(checkThen, checkElse) = evalCond(condTok);
if (checkElse)
// condition is false, we don't enter the loop
return Progress::Break;
}

forkScope(endBlock, allAnalysis.isModified());
if (bodyAnalysis.isModified()) {
Token* writeTok = findRange(endBlock->link(), endBlock, std::mem_fn(&ForwardAnalyzer::Action::isModified));
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41 changes: 41 additions & 0 deletions test/testbufferoverrun.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -156,6 +156,7 @@ class TestBufferOverrun : public TestFixture {
TEST_CASE(array_index_function_parameter);
TEST_CASE(array_index_enum_array); // #8439
TEST_CASE(array_index_container); // #9386
TEST_CASE(array_index_two_for_loops);

TEST_CASE(buffer_overrun_2_struct);
TEST_CASE(buffer_overrun_3);
Expand Down Expand Up @@ -2211,6 +2212,46 @@ class TestBufferOverrun : public TestFixture {
ASSERT_EQUALS("", errout.str());
}

void array_index_two_for_loops() {
check("bool b();\n"
"void f()\n"
"{\n"
" int val[50];\n"
" int i, sum=0;\n"
" for (i = 1; b() && i < 50; i++)\n"
" sum += val[i];\n"
" if (i < 50)\n"
" sum -= val[i];\n"
"}");
ASSERT_EQUALS("", errout.str());

check("bool b();\n"
"void f()\n"
"{\n"
" int val[50];\n"
" int i, sum=0;\n"
" for (i = 1; b() && i < 50; i++)\n"
" sum += val[i];\n"
" for (; i < 50;) {\n"
" sum -= val[i];\n"
" break;\n"
" }\n"
"}");
ASSERT_EQUALS("", errout.str());

check("bool b();\n"
"void f()\n"
"{\n"
" int val[50];\n"
" int i, sum=0;\n"
" for (i = 1; b() && i < 50; i++)\n"
" sum += val[i];\n"
" for (; i < 50; i++)\n"
" sum -= val[i];\n"
"}");
ASSERT_EQUALS("", errout.str());
}

void buffer_overrun_2_struct() {
check("struct ABC\n"
"{\n"
Expand Down