For some inputs, the constraint system can grow quite large during
solving, because it replaces complex constraints with one or more
simpler constraints. This adds a cut-off to avoid compile-time explosion
on problematic inputs.
This patch adds a isConditionImplied function that
takes a constraint and returns true if the constraint
is implied by the current constraints in the system.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D84545
This patch recommits "[ConstraintSystem] Add helpers to deal with linear constraints."
(it reverts the revert commit 8da6ae4ce1).
The reason for the revert was using __builtin_multiply_overflow, which
is not available for all compilers. The patch has been updated to use
MulOverflow from MathExtras.h
This patch introduces a new ConstraintSystem class, that maintains a set
of linear constraints and uses Fourier–Motzkin elimination to eliminate
constraints to check if there are solutions for the system.
It also adds a convert-constraint-log-to-z3.py script, which can parse
the debug output of the constraint system and convert it to a python
script that feeds the constraints into Z3 and checks if it produces the
same result as the LLVM implementation. This is for verification
purposes.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D84544
Kazu Hirata