[tests] Add indvars tests showing missing transforms with small IVs

This shows the transform side of D109457, but also lets us try other approaches to the same problem.  The common trend to all is that we need to explicit reason about UB to disallow possibility of infinite loops.

diff --git a/llvm/test/Transforms/IndVarSimplify/finite-exit-comparisons.ll b/llvm/test/Transforms/IndVarSimplify/finite-exit-comparisons.ll
new file mode 100644 (file)
index 0000000..45980be
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/finite-exit-comparisons.ll
@@ -0,0 +1,672 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -indvars -S < %s | FileCheck %s
+
+; A collection of tests which domonstrate cases where we can use properties
+; of the loop (i.e. single exit, finite, mustprogress) to optimize conditions
+; and extends we couldn't otherwise handle.
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+define void @slt_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @slt_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @slt_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @slt_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+; Case where we could prove this using range facts, but not must exit reasoning
+define void @slt_non_constant_rhs_no_mustprogress(i16 %n.raw) {
+; CHECK-LABEL: @slt_non_constant_rhs_no_mustprogress(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[N:%.*]] = and i16 [[N_RAW:%.*]], 255
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], [[N]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %n = and i16 %n.raw, 255
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+@G = external global i8
+
+; Negative case where the loop could be infinite and make progress
+define void @slt_neg_well_defined_infinite(i16 %n) mustprogress {
+; CHECK-LABEL: @slt_neg_well_defined_infinite(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    store volatile i8 [[IV]], i8* @G, align 1
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  store volatile i8 %iv, i8* @G
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+; Negative case with no mustprogress rsltuirement
+define void @slt_neg_no_mustprogress(i16 %n) {
+; CHECK-LABEL: @slt_neg_no_mustprogress(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+declare void @unknown()
+
+define void @slt_neg_abnormal_exit(i16 %n) mustprogress {
+; CHECK-LABEL: @slt_neg_abnormal_exit(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  call void @unknown()
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp slt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+; For the other comparison flavors, we only bother to repeat the positive
+; tests since the negative variants are mostly the same.
+
+define void @ne_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @ne_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ne i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ne_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @ne_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ne i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @eq_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @eq_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp eq i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @eq_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @eq_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp eq i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sgt_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @sgt_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sgt i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sgt_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @sgt_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sgt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sle_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @sle_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sle i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sle i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sle_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @sle_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sle i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sle i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sge_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @sge_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sge i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @sge_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @sge_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp sge i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ult_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @ult_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ult i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ult_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @ult_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ult i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ugt_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @ugt_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ugt i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ugt_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @ugt_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ugt i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ule_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @ule_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ule i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ule i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @ule_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @ule_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ule i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp ule i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @uge_constant_rhs(i16 %n.raw, i8 %start) mustprogress {
+; CHECK-LABEL: @uge_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp uge i16 [[ZEXT]], 254
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ %start, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp uge i16 %zext, 254
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+define void @uge_non_constant_rhs(i16 %n) mustprogress {
+; CHECK-LABEL: @uge_non_constant_rhs(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i8 [[IV]], 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
+; CHECK-NEXT:    [[CMP:%.*]] = icmp uge i16 [[ZEXT]], [[N:%.*]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
+; CHECK:       for.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %entry, %for.body
+  %iv = phi i8 [ %iv.next, %for.body ], [ 0, %entry ]
+  %iv.next = add i8 %iv, 1
+  %zext = zext i8 %iv.next to i16
+  %cmp = icmp uge i16 %zext, %n
+  br i1 %cmp, label %for.body, label %for.end
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}