[ConstraintSolver] Add isConditionImplied helper.

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

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ConstraintSystem.cpp b/llvm/lib/Analysis/ConstraintSystem.cpp
index 21115fc..818cfe0 100644
--- a/llvm/lib/Analysis/ConstraintSystem.cpp
+++ b/llvm/lib/Analysis/ConstraintSystem.cpp
@@ -140,3 +140,13 @@ bool ConstraintSystem::mayHaveSolution() {
   LLVM_DEBUG(dbgs() << (HasSolution ? "sat" : "unsat") << "\n");
   return HasSolution;
 }
+
+bool ConstraintSystem::isConditionImplied(SmallVector<int64_t, 8> R) {
+  // If there is no solution with the negation of R added to the system, the
+  // condition must hold based on the existing constraints.
+  R = ConstraintSystem::negate(R);
+
+  auto NewSystem = *this;
+  NewSystem.addVariableRow(R);
+  return !NewSystem.mayHaveSolution();
+}