[ConstraintElimination] Add support for Or.

llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

static bool eliminateConstraints(Function &F, DominatorTree &DT) {
   for (BasicBlock &BB : F) {
     if (!DT.getNode(&BB))
       continue;
     WorkList.emplace_back(DT.getNode(&BB));
 
     auto *Br = dyn_cast<BranchInst>(BB.getTerminator());
     if (!Br || !Br->isConditional())
       continue;
+
+    if (match(Br->getCondition(), m_Or(m_Cmp(), m_Cmp()))) {
+      if (Br->getSuccessor(1)->getSinglePredecessor()) {
+        auto *OrI = cast<Instruction>(Br->getCondition());
+        WorkList.emplace_back(DT.getNode(Br->getSuccessor(1)),
+                              cast<CmpInst>(OrI->getOperand(0)), true);
+        WorkList.emplace_back(DT.getNode(Br->getSuccessor(1)),
+                              cast<CmpInst>(OrI->getOperand(1)), true);
+      }
+      continue;
+    }
+
     auto *CmpI = dyn_cast<CmpInst>(Br->getCondition());
     if (!CmpI)
       continue;
     if (Br->getSuccessor(0)->getSinglePredecessor())
       WorkList.emplace_back(DT.getNode(Br->getSuccessor(0)), CmpI, false);
     if (Br->getSuccessor(1)->getSinglePredecessor())
       WorkList.emplace_back(DT.getNode(Br->getSuccessor(1)), CmpI, true);
   }

llvm/test/Transforms/ConstraintElimination/or.ll

 ; CHECK:       bb1:
 ; CHECK-NEXT:    [[C_3:%.*]] = icmp ule i32 [[X]], [[Z]]
 ; CHECK-NEXT:    call void @use(i1 [[C_3]])
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp ule i32 [[X]], [[A:%.*]]
 ; CHECK-NEXT:    call void @use(i1 [[C_4]])
 ; CHECK-NEXT:    ret i32 10
 ; CHECK:       exit:
 ; CHECK-NEXT:    [[F_1:%.*]] = icmp ule i32 [[X]], [[Z]]
-; CHECK-NEXT:    call void @use(i1 [[F_1]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ule i32 [[X]], [[A]]
 ; CHECK-NEXT:    call void @use(i1 [[C_5]])
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp ugt i32 [[Y]], [[Z]]
-; CHECK-NEXT:    call void @use(i1 [[T_1]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ugt i32 [[X]], [[Y]]
-; CHECK-NEXT:    call void @use(i1 [[T_2]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ugt i32 [[X]], [[Z]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    ret i32 20
 ;
 entry:
   %c.1 = icmp ule i32 %x, %y
   %c.2 = icmp ule i32 %y, %z
   %or = or i1 %c.1, %c.2
   br i1 %or, label %bb1, label %exit