[ValueTracking] Add tests for deducing more conditions in `isTruePredicate`; NFC

2 files changed, 466 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/implies.ll b/llvm/test/Transforms/InstCombine/implies.ll
new file mode 100644
index 0000000..6741d59
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/implies.ll
@@ -0,0 +1,440 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @or_implies_sle(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @or_implies_sle(
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[X:%.*]], 23
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[OR]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %or = or i8 %x, 23
+  %cond = icmp sle i8 %or, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @or_implies_sle_fail(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @or_implies_sle_fail(
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[X:%.*]], -34
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[OR]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %or = or i8 %x, -34
+  %cond = icmp sle i8 %or, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @or_distjoint_implies_ule(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @or_distjoint_implies_ule(
+; CHECK-NEXT:    [[X2:%.*]] = or disjoint i8 [[X:%.*]], 24
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = or disjoint i8 [[X]], 23
+; CHECK-NEXT:    [[R:%.*]] = icmp ule i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = or disjoint i8 %x, 23
+  %x2 = or disjoint i8 %x, 24
+
+  %cond = icmp ule i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp ule i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @or_distjoint_implies_ule_fail(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @or_distjoint_implies_ule_fail(
+; CHECK-NEXT:    [[X2:%.*]] = or disjoint i8 [[X:%.*]], 24
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = or disjoint i8 [[X]], 28
+; CHECK-NEXT:    [[R:%.*]] = icmp ule i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = or disjoint i8 %x, 28
+  %x2 = or disjoint i8 %x, 24
+
+  %cond = icmp ule i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp ule i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @or_prove_distjoin_implies_ule(i8 %xx, i8 %y, i1 %other) {
+; CHECK-LABEL: @or_prove_distjoin_implies_ule(
+; CHECK-NEXT:    [[X:%.*]] = and i8 [[XX:%.*]], -16
+; CHECK-NEXT:    [[X2:%.*]] = or disjoint i8 [[X]], 10
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    ret i1 true
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x = and i8 %xx, -16
+  %x1 = or i8 %x, 7
+  %x2 = or i8 %x, 10
+
+  %cond = icmp ule i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp ule i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_or_distjoint_implies_sle(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @src_or_distjoint_implies_sle(
+; CHECK-NEXT:    [[X2:%.*]] = or disjoint i8 [[X:%.*]], 24
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = or disjoint i8 [[X]], 23
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = or disjoint i8 %x, 23
+  %x2 = or disjoint i8 %x, 24
+
+  %cond = icmp sle i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_or_distjoint_implies_sle_fail(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @src_or_distjoint_implies_sle_fail(
+; CHECK-NEXT:    [[X2:%.*]] = or disjoint i8 [[X:%.*]], 24
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp slt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = or disjoint i8 [[X]], 23
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = or disjoint i8 %x, 23
+  %x2 = or disjoint i8 %x, 24
+
+  %cond = icmp sle i8 %y, %x2
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_addnsw_implies_sle(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @src_addnsw_implies_sle(
+; CHECK-NEXT:    [[X2:%.*]] = add nsw i8 [[X:%.*]], 24
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = add nsw i8 [[X]], 23
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = add nsw i8 %x, 23
+  %x2 = add nsw i8 %x, 24
+
+  %cond = icmp sle i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_addnsw_implies_sle_fail(i8 %x, i8 %y, i1 %other) {
+; CHECK-LABEL: @src_addnsw_implies_sle_fail(
+; CHECK-NEXT:    [[X2:%.*]] = add nsw i8 [[X:%.*]], 23
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[X2]], [[Y:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[X1:%.*]] = add nsw i8 [[X]], 24
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X1]], [[Y]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %x1 = add nsw i8 %x, 24
+  %x2 = add nsw i8 %x, 23
+
+  %cond = icmp sle i8 %x2, %y
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x1, %y
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_and_implies_ult(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_and_implies_ult(
+; CHECK-NEXT:    [[COND:%.*]] = icmp ult i8 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[AND:%.*]] = and i8 [[Z]], [[X]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[AND]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp ult i8 %x, %z
+  br i1 %cond, label %T, label %F
+T:
+  %and = and i8 %z, %x
+  %r = icmp ult i8 %and, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_and_implies_ult_fail(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_and_implies_ult_fail(
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[AND:%.*]] = and i8 [[X]], [[Z]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ne i8 [[AND]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp ule i8 %x, %z
+  br i1 %cond, label %T, label %F
+T:
+  %and = and i8 %x, %z
+  %r = icmp ult i8 %and, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_and_implies_slt_fail(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_and_implies_slt_fail(
+; CHECK-NEXT:    [[COND:%.*]] = icmp slt i8 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[AND:%.*]] = and i8 [[X]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[AND]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp slt i8 %x, %z
+  br i1 %cond, label %T, label %F
+T:
+  %and = and i8 %x, %y
+  %r = icmp slt i8 %and, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_or_implies_ule(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_or_implies_ule(
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[Y:%.*]], [[X:%.*]]
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[OR]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[R:%.*]] = icmp ule i8 [[X]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %or = or i8 %y, %x
+  %cond = icmp uge i8 %z, %or
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp ule i8 %x, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_or_implies_false_ugt_todo(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_or_implies_false_ugt_todo(
+; CHECK-NEXT:    [[OR:%.*]] = or i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[COND:%.*]] = icmp ugt i8 [[OR]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+; CHECK:       F:
+; CHECK-NEXT:    [[R:%.*]] = icmp ugt i8 [[X]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %or = or i8 %x, %y
+  %cond = icmp ugt i8 %or, %z
+  br i1 %cond, label %T, label %F
+T:
+  ret i1 %other
+F:
+  %r = icmp ugt i8 %x, %z
+  ret i1 %r
+
+}
+
+define i1 @src_udiv_implies_ult(i8 %x, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_udiv_implies_ult(
+; CHECK-NEXT:    [[COND:%.*]] = icmp ugt i8 [[Z:%.*]], [[X:%.*]]
+; CHECK-NEXT:    br i1 [[COND]], label [[T:%.*]], label [[F:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[AND:%.*]] = udiv i8 [[X]], 3
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i8 [[AND]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp ugt i8 %z, %x
+  br i1 %cond, label %T, label %F
+T:
+  %and = udiv i8 %x, 3
+  %r = icmp ult i8 %and, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_udiv_implies_ult2(i8 %x, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_udiv_implies_ult2(
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[Z:%.*]], [[X:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+; CHECK:       F:
+; CHECK-NEXT:    [[AND:%.*]] = udiv i8 [[X]], 3
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i8 [[AND]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %cond = icmp ule i8 %z, %x
+  br i1 %cond, label %T, label %F
+T:
+  ret i1 %other
+F:
+  %and = udiv i8 %x, 3
+  %r = icmp ult i8 %and, %z
+  ret i1 %r
+}
+
+define i1 @src_smin_implies_sle(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_smin_implies_sle(
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    ret i1 true
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp sle i8 %x, %z
+  br i1 %cond, label %T, label %F
+T:
+  %um = call i8 @llvm.smin.i8(i8 %x, i8 %y)
+  %r = icmp sle i8 %um, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_umin_implies_ule(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_umin_implies_ule(
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[X:%.*]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    ret i1 true
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %cond = icmp ule i8 %x, %z
+  br i1 %cond, label %T, label %F
+T:
+  %um = call i8 @llvm.umin.i8(i8 %x, i8 %y)
+  %r = icmp ule i8 %um, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_umax_implies_ule(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_umax_implies_ule(
+; CHECK-NEXT:    [[UM:%.*]] = call i8 @llvm.umax.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp ugt i8 [[UM]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[R:%.*]] = icmp ule i8 [[X]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %um = call i8 @llvm.umax.i8(i8 %x, i8 %y)
+  %cond = icmp ule i8 %um, %z
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp ule i8 %x, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
+
+define i1 @src_smax_implies_sle(i8 %x, i8 %y, i8 %z, i1 %other) {
+; CHECK-LABEL: @src_smax_implies_sle(
+; CHECK-NEXT:    [[UM:%.*]] = call i8 @llvm.smax.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
+; CHECK-NEXT:    [[COND_NOT:%.*]] = icmp sgt i8 [[UM]], [[Z:%.*]]
+; CHECK-NEXT:    br i1 [[COND_NOT]], label [[F:%.*]], label [[T:%.*]]
+; CHECK:       T:
+; CHECK-NEXT:    [[R:%.*]] = icmp sle i8 [[X]], [[Z]]
+; CHECK-NEXT:    ret i1 [[R]]
+; CHECK:       F:
+; CHECK-NEXT:    ret i1 [[OTHER:%.*]]
+;
+  %um = call i8 @llvm.smax.i8(i8 %x, i8 %y)
+  %cond = icmp sle i8 %um, %z
+  br i1 %cond, label %T, label %F
+T:
+  %r = icmp sle i8 %x, %z
+  ret i1 %r
+F:
+  ret i1 %other
+}
diff --git a/llvm/test/Transforms/InstSimplify/implies.ll b/llvm/test/Transforms/InstSimplify/implies.ll
index b70dc90..8a01190 100644
--- a/llvm/test/Transforms/InstSimplify/implies.ll
+++ b/llvm/test/Transforms/InstSimplify/implies.ll
@@ -166,6 +166,19 @@ define i1 @test10(i32 %length.i, i32 %x.full) {
   ret i1 %res
 }
 
+define i1 @test10_with_disjoint(i32 %length.i, i32 %x.full) {
+; CHECK-LABEL: @test10_with_disjoint(
+; CHECK-NEXT:    ret i1 true
+;
+  %x = and i32 %x.full, 4294901760  ;; 4294901760 == 0xffff0000
+  %large = or disjoint i32 %x, 100
+  %small = or disjoint i32 %x, 90
+  %known = icmp ult i32 %large, %length.i
+  %to.prove = icmp ult i32 %small, %length.i
+  %res = icmp ule i1 %known, %to.prove
+  ret i1 %res
+}
+
 define i1 @test11(i32 %length.i, i32 %x) {
 ; CHECK-LABEL: @test11(
 ; CHECK-NEXT:    [[LARGE:%.*]] = or i32 [[X:%.*]], 100
@@ -227,6 +240,19 @@ define i1 @test14(i32 %length.i, i32 %x.full) {
   ret i1 %res
 }
 
+define i1 @test14_with_disjoint(i32 %length.i, i32 %x.full) {
+; CHECK-LABEL: @test14_with_disjoint(
+; CHECK-NEXT:    ret i1 true
+;
+  %x = and i32 %x.full, 4294905615  ;; 4294905615 == 0xffff0f0f
+  %large = or disjoint i32 %x, 8224 ;; == 0x2020
+  %small = or disjoint i32 %x, 4112 ;; == 0x1010
+  %known = icmp ult i32 %large, %length.i
+  %to.prove = icmp ult i32 %small, %length.i
+  %res = icmp ule i1 %known, %to.prove
+  ret i1 %res
+}
+
 define i1 @test15(i32 %length.i, i32 %x) {
 ; CHECK-LABEL: @test15(
 ; CHECK-NEXT:    [[LARGE:%.*]] = add nuw i32 [[X:%.*]], 100