[IndVars] Add test for #102597 (NFC)

Author: nikic

llvm/test/Transforms/IndVarSimplify/pr102597.ll

@@ -0,0 +1,43 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S -passes=indvars < %s | FileCheck %s
+
+; FIXME: This is a miscompile.
+define void @test() {
+; CHECK-LABEL: define void @test() {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i128 [ 3, %[[ENTRY]] ], [ [[IV_DEC:%.*]], %[[LOOP_LATCH:.*]] ]
+; CHECK-NEXT:    br i1 true, label %[[LOOP_LATCH]], label %[[IF:.*]]
+; CHECK:       [[IF]]:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label %[[LOOP_LATCH]]
+; CHECK:       [[LOOP_LATCH]]:
+; CHECK-NEXT:    [[IV_DEC]] = add nsw i128 [[IV]], -1
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i128 [[IV]], 0
+; CHECK-NEXT:    br i1 [[CMP]], label %[[LOOP]], label %[[EXIT:.*]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i128 [ 3, %entry ], [ %iv.dec, %loop.latch ]
+  %tobool = icmp ne i128 %iv, 0
+  br i1 %tobool, label %loop.latch, label %if
+
+if:
+  call void @foo()
+  br label %loop.latch
+
+loop.latch:
+  %iv.dec = add nsw i128 %iv, -1
+  %cmp = icmp sgt i128 %iv, 0
+  br i1 %cmp, label %loop, label %exit
+
+exit:
+  ret void
+}
+
+declare void @foo()