https://bugs.llvm.org/show_bug.cgi?id=33430
Bug ID: 33430
Summary: [ubsan] false negative: pointer overflow check misses
subtractions with unsigned offsets
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: LLVM Codegen
Assignee: unassignedclangb...@nondot.org
Reporter: v...@apple.com
CC: llvm-bugs@lists.llvm.org
This has been a problem with the pointer overflow check since it was introduced
in r304459.
An example from Eli: "p - SIZE_MAX" gets converted into (gep p 0 1), so
EmitCheckedInBoundsGEP expects the result of the gep to be "greater than" p.
This is wrong.
We should always expect "ptrtoint(p - <unsigned>) <= ptrtoint(p)".
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