From a093942c287501484481384dd03686ffaa5fc98e Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Mon, 8 Mar 2021 08:39:56 -0500
Subject: [PATCH] [ConstProp][JumpThreading] add more test coverage for
 potential nullptr folds; NFC

See D98150.
---
 .../Transforms/InstSimplify/ConstProp/icmp-null.ll | 24 +++++++++
 .../Transforms/JumpThreading/thread-two-bbs.ll     | 58 +++++++++++++++++++++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll b/llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll
index 5ee8e7a..57aea10 100644
--- a/llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll
+++ b/llvm/test/Transforms/InstSimplify/ConstProp/icmp-null.ll
@@ -32,3 +32,27 @@ define i1 @ult_constexpr_null(i8* %x) {
   %cmp = icmp ult i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), null
   ret i1 %cmp
 }
+
+define i1 @ule_constexpr_null(i8* %x) {
+; CHECK-LABEL: @ule_constexpr_null(
+; CHECK-NEXT:    ret i1 icmp ule (i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), i8 (...)* null)
+;
+  %cmp = icmp ule i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), null
+  ret i1 %cmp
+}
+
+define i1 @slt_constexpr_null(i8* %x) {
+; CHECK-LABEL: @slt_constexpr_null(
+; CHECK-NEXT:    ret i1 icmp slt (i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), i8 (...)* null)
+;
+  %cmp = icmp slt i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), null
+  ret i1 %cmp
+}
+
+define i1 @ult_constexpr_constexpr_one(i8* %x) {
+; CHECK-LABEL: @ult_constexpr_constexpr_one(
+; CHECK-NEXT:    ret i1 icmp ult (i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), i8 (...)* inttoptr (i32 1 to i8 (...)*))
+;
+  %cmp = icmp ult i8 (...)* bitcast (i1 (i8*)* @ugt_null_constexpr to i8 (...)*), inttoptr (i32 1 to i8 (...)*)
+  ret i1 %cmp
+}
diff --git a/llvm/test/Transforms/JumpThreading/thread-two-bbs.ll b/llvm/test/Transforms/JumpThreading/thread-two-bbs.ll
index be4f6d7..fd4ec00 100644
--- a/llvm/test/Transforms/JumpThreading/thread-two-bbs.ll
+++ b/llvm/test/Transforms/JumpThreading/thread-two-bbs.ll
@@ -137,8 +137,62 @@ exit:
 ;
 ; as "true", causing jump threading to a wrong destination.
 
-define void @foo3(i8* %arg1, i8* %arg2) {
-; CHECK-LABEL: @foo3(
+define void @icmp_ult_null_constexpr(i8* %arg1, i8* %arg2) {
+; CHECK-LABEL: @icmp_ult_null_constexpr(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i8* [[ARG1:%.*]], null
+; CHECK-NEXT:    br i1 [[CMP1]], label [[BB_BAR1:%.*]], label [[BB_END:%.*]]
+; CHECK:       bb_bar1:
+; CHECK-NEXT:    call void @bar(i32 1)
+; CHECK-NEXT:    br label [[BB_END]]
+; CHECK:       bb_end:
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ne i8* [[ARG2:%.*]], null
+; CHECK-NEXT:    br i1 [[CMP2]], label [[BB_CONT:%.*]], label [[BB_BAR2:%.*]]
+; CHECK:       bb_bar2:
+; CHECK-NEXT:    call void @bar(i32 2)
+; CHECK-NEXT:    br label [[BB_EXIT:%.*]]
+; CHECK:       bb_cont:
+; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult i8* [[ARG1]], inttoptr (i64 4 to i8*)
+; CHECK-NEXT:    br i1 [[CMP3]], label [[BB_EXIT]], label [[BB_BAR3:%.*]]
+; CHECK:       bb_bar3:
+; CHECK-NEXT:    call void @bar(i32 3)
+; CHECK-NEXT:    br label [[BB_EXIT]]
+; CHECK:       bb_exit:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cmp1 = icmp eq i8* %arg1, null
+  br i1 %cmp1, label %bb_bar1, label %bb_end
+
+bb_bar1:
+  call void @bar(i32 1)
+  br label %bb_end
+
+bb_end:
+  %cmp2 = icmp ne i8* %arg2, null
+  br i1 %cmp2, label %bb_cont, label %bb_bar2
+
+bb_bar2:
+  call void @bar(i32 2)
+  br label %bb_exit
+
+bb_cont:
+  %cmp3 = icmp ult i8* %arg1, inttoptr (i64 4 to i8*)
+  br i1 %cmp3, label %bb_exit, label %bb_bar3
+
+bb_bar3:
+  call void @bar(i32 3)
+  br label %bb_exit
+
+bb_exit:
+  ret void
+}
+
+; TODO: This is a special-case of the above pattern:
+; Null is guaranteed to be unsigned <= all values.
+
+define void @icmp_ule_null_constexpr(i8* %arg1, i8* %arg2) {
+; CHECK-LABEL: @icmp_ule_null_constexpr(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i8* [[ARG1:%.*]], null
 ; CHECK-NEXT:    br i1 [[CMP1]], label [[BB_BAR1:%.*]], label [[BB_END:%.*]]
-- 
2.7.4