http://llvm.org/bugs/show_bug.cgi?id=20199
Bug ID: 20199
Summary: An integer overflow bug in
InstructionSimplify.cpp:SimplifyICmpInst introduced in
r208999: sdiv const, value
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Global Analyses
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
If a first sdiv argument + 1 overflows, a wrong range is calculated.
A test case (should be compiled with clang with -O1):
extern void abort(void);
int main (void)
{
volatile long int n;
n = -2;
if ((-2147483647L - 1L) / (-n) != -1073741824L)
abort ();
return 0;
}
A simple overflow check at around the following lines should fix the issue:
} else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
// 'sdiv CI2, x' produces [-|CI2|, |CI2|].
Upper = CI2->getValue().abs() + 1;
Lower = (-Upper) + 1;
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