Added regression test

Author: grigorypas

llvm/test/Transforms/ConstraintElimination/loop-removal.ll

@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=constraint-elimination -S | FileCheck %s
+
+define i32 @foo() {
+; CHECK-LABEL: define i32 @foo() {
+; CHECK-NEXT:  init:
+; CHECK-NEXT:    br label %[[OUTER_LOOP_CONTROL:.*]]
+; CHECK:       outer.loop.control:
+; CHECK-NEXT:    [[X_0:%.*]] = phi i32 [ 0, [[INIT:%.*]] ], [ [[X_OUTER:%.*]], %[[OUTER_LOOP_INC:.*]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i32 [[X_0]], 10
+; CHECK-NEXT:    br i1 [[TMP0]], label %[[INNER_LOOP_CONTROL:.*]], label %[[EXIT:.*]]
+; CHECK:       inner.loop.control:
+; CHECK-NEXT:    [[X_1:%.*]] = phi i32 [ [[X_0]], %[[OUTER_LOOP_CONTROL]] ], [ [[X_INNER:%.*]], %[[INNER_LOOP_BODY:.*]] ]
+; CHECK-NEXT:    br i1 false, label %[[INNER_LOOP_BODY]], label %[[OUTER_LOOP_INC]]
+; CHECK:       inner.loop.body:
+; CHECK-NEXT:    [[X_INNER]] = add nsw i32 [[X_1]], -1
+; CHECK-NEXT:    br label %[[INNER_LOOP_CONTROL]]
+; CHECK:       outer.loop.inc:
+; CHECK-NEXT:    [[X_OUTER]] = add nsw i32 [[X_1]], 2
+; CHECK-NEXT:    br label %[[OUTER_LOOP_CONTROL]]
+; CHECK:       exit:
+; CHECK-NEXT:    ret i32 [[X_0]]
+;
+init:
+  br label %outer.loop.control
+
+outer.loop.control:                                                ; preds = %init, %outer.loop.inc
+  %x.0 = phi i32 [ 0, %init ], [ %x.outer, %outer.loop.inc ]
+  %0 = icmp slt i32 %x.0, 10
+  br i1 %0, label %inner.loop.control, label %exit
+
+inner.loop.control:                                                ; preds = %outer.loop.control, %inner.loop.body
+  %x.1 = phi i32 [ %x.0, %outer.loop.control ], [ %x.inner, %inner.loop.body ]
+  %1 = icmp sgt i32 %x.1, 20
+  br i1 %1, label %inner.loop.body, label %outer.loop.inc
+
+inner.loop.body:                                                ; preds = %inner.loop.control
+  %x.inner = add nsw i32 %x.1, -1
+  br label %inner.loop.control
+
+outer.loop.inc:                                                ; preds = %inner.loop.control
+  %x.outer = add nsw i32 %x.1, 2
+  br label %outer.loop.control
+
+exit:                                               ; preds = %1
+  ret i32 %x.0
+}