From 139a9d6c0e0d872f0f41f94f621c616d8459817a Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Sun, 8 Sep 2019 21:30:34 +0000
Subject: [PATCH] [InstCombine][NFC] Some tests for usub overflow+nonzero check
 improvement (PR43251)

https://rise4fun.com/Alive/kHq

https://bugs.llvm.org/show_bug.cgi?id=43251

llvm-svn: 371352
---
 .../result-of-usub-is-non-zero-and-no-overflow.ll  | 343 +++++++++++++++++++++
 1 file changed, 343 insertions(+)
 create mode 100644 llvm/test/Transforms/InstCombine/result-of-usub-is-non-zero-and-no-overflow.ll

diff --git a/llvm/test/Transforms/InstCombine/result-of-usub-is-non-zero-and-no-overflow.ll b/llvm/test/Transforms/InstCombine/result-of-usub-is-non-zero-and-no-overflow.ll
new file mode 100644
index 0000000..0ae9219
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/result-of-usub-is-non-zero-and-no-overflow.ll
@@ -0,0 +1,343 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; Here we subtract two values, check that subtraction did not overflow AND
+; that the result is non-zero. This can be simplified just to a comparison
+; between the base and offset.
+
+declare void @use8(i8)
+declare void @use1(i1)
+
+declare {i8, i1} @llvm.usub.with.overflow(i8, i8)
+declare void @useagg({i8, i1})
+
+; There is a number of base patterns..
+
+define i1 @t0_noncanonical_ignoreme(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t0_noncanonical_ignoreme(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp ule i8 %adjusted, %base
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = and i1 %not_null, %no_underflow
+  ret i1 %r
+}
+
+define i1 @t1(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t1(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp uge i8 %base, %offset
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = and i1 %not_null, %no_underflow
+  ret i1 %r
+}
+
+define i1 @t2(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t2(
+; CHECK-NEXT:    [[AGG:%.*]] = call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[BASE:%.*]], i8 [[OFFSET:%.*]])
+; CHECK-NEXT:    call void @useagg({ i8, i1 } [[AGG]])
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = extractvalue { i8, i1 } [[AGG]], 0
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = extractvalue { i8, i1 } [[AGG]], 1
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = xor i1 [[UNDERFLOW]], true
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %agg = call {i8, i1} @llvm.usub.with.overflow(i8 %base, i8 %offset)
+  call void @useagg({i8, i1} %agg)
+  %adjusted = extractvalue {i8, i1} %agg, 0
+  call void @use8(i8 %adjusted)
+  %underflow = extractvalue {i8, i1} %agg, 1
+  call void @use1(i1 %underflow)
+  %no_underflow = xor i1 %underflow, -1
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  %r = and i1 %not_null, %no_underflow
+  ret i1 %r
+}
+
+; Commutativity
+
+define i1 @t3_commutability0(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t3_commutability0(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp ule i8 %offset, %base ; swapped
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = and i1 %not_null, %no_underflow
+  ret i1 %r
+}
+define i1 @t4_commutability1(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t4_commutability1(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp ule i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NO_UNDERFLOW]], [[NOT_NULL]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp ule i8 %base, %offset ; swapped
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = and i1 %no_underflow, %not_null ; swapped
+  ret i1 %r
+}
+define i1 @t5_commutability2(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t5_commutability2(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NO_UNDERFLOW]], [[NOT_NULL]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp ule i8 %offset, %base ; swapped
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = and i1 %no_underflow, %not_null ; swapped
+  ret i1 %r
+}
+
+define i1 @t6_commutability(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t6_commutability(
+; CHECK-NEXT:    [[AGG:%.*]] = call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[BASE:%.*]], i8 [[OFFSET:%.*]])
+; CHECK-NEXT:    call void @useagg({ i8, i1 } [[AGG]])
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = extractvalue { i8, i1 } [[AGG]], 0
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = extractvalue { i8, i1 } [[AGG]], 1
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = xor i1 [[UNDERFLOW]], true
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %agg = call {i8, i1} @llvm.usub.with.overflow(i8 %base, i8 %offset)
+  call void @useagg({i8, i1} %agg)
+  %adjusted = extractvalue {i8, i1} %agg, 0
+  call void @use8(i8 %adjusted)
+  %underflow = extractvalue {i8, i1} %agg, 1
+  call void @use1(i1 %underflow)
+  %no_underflow = xor i1 %underflow, -1
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  %r = and i1 %no_underflow, %not_null ; swapped
+  ret i1 %r
+}
+
+; What if we were checking the opposite question, that we either got null,
+; or overflow happened?
+
+define i1 @t7(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t7(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = icmp ult i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NULL]])
+; CHECK-NEXT:    [[R:%.*]] = or i1 [[NULL]], [[UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %underflow = icmp ugt i8 %adjusted, %base
+  call void @use1(i1 %underflow)
+  %null = icmp eq i8 %adjusted, 0
+  call void @use1(i1 %null)
+  %r = or i1 %null, %underflow
+  ret i1 %r
+}
+
+define i1 @t8(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t8(
+; CHECK-NEXT:    [[AGG:%.*]] = call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[BASE:%.*]], i8 [[OFFSET:%.*]])
+; CHECK-NEXT:    call void @useagg({ i8, i1 } [[AGG]])
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = extractvalue { i8, i1 } [[AGG]], 0
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = extractvalue { i8, i1 } [[AGG]], 1
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    [[R:%.*]] = or i1 [[NULL]], [[UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %agg = call {i8, i1} @llvm.usub.with.overflow(i8 %base, i8 %offset)
+  call void @useagg({i8, i1} %agg)
+  %adjusted = extractvalue {i8, i1} %agg, 0
+  call void @use8(i8 %adjusted)
+  %underflow = extractvalue {i8, i1} %agg, 1
+  call void @use1(i1 %underflow)
+  %null = icmp eq i8 %adjusted, 0
+  %r = or i1 %null, %underflow
+  ret i1 %r
+}
+
+; And these patterns also have commutative variants
+
+define i1 @t9_commutative(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t9_commutative(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = icmp ult i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NULL]])
+; CHECK-NEXT:    [[R:%.*]] = or i1 [[NULL]], [[UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %underflow = icmp ult i8 %base, %adjusted ; swapped
+  call void @use1(i1 %underflow)
+  %null = icmp eq i8 %adjusted, 0
+  call void @use1(i1 %null)
+  %r = or i1 %null, %underflow
+  ret i1 %r
+}
+
+;-------------------------------------------------------------------------------
+
+; If we are checking that we either did not get null or got no overflow,
+; this is tautological and is always true.
+
+define i1 @t10(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t10(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp uge i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NOT_NULL]])
+; CHECK-NEXT:    [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %no_underflow = icmp uge i8 %base, %offset
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  call void @use1(i1 %not_null)
+  %r = or i1 %not_null, %no_underflow
+  ret i1 %r
+}
+
+define i1 @t11(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t11(
+; CHECK-NEXT:    [[AGG:%.*]] = call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[BASE:%.*]], i8 [[OFFSET:%.*]])
+; CHECK-NEXT:    call void @useagg({ i8, i1 } [[AGG]])
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = extractvalue { i8, i1 } [[AGG]], 0
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = extractvalue { i8, i1 } [[AGG]], 1
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = xor i1 [[UNDERFLOW]], true
+; CHECK-NEXT:    call void @use1(i1 [[NO_UNDERFLOW]])
+; CHECK-NEXT:    [[NOT_NULL:%.*]] = icmp ne i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    [[R:%.*]] = or i1 [[NOT_NULL]], [[NO_UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %agg = call {i8, i1} @llvm.usub.with.overflow(i8 %base, i8 %offset)
+  call void @useagg({i8, i1} %agg)
+  %adjusted = extractvalue {i8, i1} %agg, 0
+  call void @use8(i8 %adjusted)
+  %underflow = extractvalue {i8, i1} %agg, 1
+  call void @use1(i1 %underflow)
+  %no_underflow = xor i1 %underflow, -1
+  call void @use1(i1 %no_underflow)
+  %not_null = icmp ne i8 %adjusted, 0
+  %r = or i1 %not_null, %no_underflow
+  ret i1 %r
+}
+
+; Likewise, if we are checking that we both got null and overflow happened,
+; it makes no sense and is always false.
+
+define i1 @t12(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t12(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = icmp ult i8 [[BASE]], [[OFFSET]]
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    call void @use1(i1 [[NULL]])
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NULL]], [[UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %adjusted = sub i8 %base, %offset
+  call void @use8(i8 %adjusted)
+  %underflow = icmp ugt i8 %adjusted, %base
+  call void @use1(i1 %underflow)
+  %null = icmp eq i8 %adjusted, 0
+  call void @use1(i1 %null)
+  %r = and i1 %null, %underflow
+  ret i1 %r
+}
+
+define i1 @t13(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t13(
+; CHECK-NEXT:    [[AGG:%.*]] = call { i8, i1 } @llvm.usub.with.overflow.i8(i8 [[BASE:%.*]], i8 [[OFFSET:%.*]])
+; CHECK-NEXT:    call void @useagg({ i8, i1 } [[AGG]])
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = extractvalue { i8, i1 } [[AGG]], 0
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = extractvalue { i8, i1 } [[AGG]], 1
+; CHECK-NEXT:    call void @use1(i1 [[UNDERFLOW]])
+; CHECK-NEXT:    [[NULL:%.*]] = icmp eq i8 [[ADJUSTED]], 0
+; CHECK-NEXT:    [[R:%.*]] = and i1 [[NULL]], [[UNDERFLOW]]
+; CHECK-NEXT:    ret i1 [[R]]
+;
+  %agg = call {i8, i1} @llvm.usub.with.overflow(i8 %base, i8 %offset)
+  call void @useagg({i8, i1} %agg)
+  %adjusted = extractvalue {i8, i1} %agg, 0
+  call void @use8(i8 %adjusted)
+  %underflow = extractvalue {i8, i1} %agg, 1
+  call void @use1(i1 %underflow)
+  %null = icmp eq i8 %adjusted, 0
+  %r = and i1 %null, %underflow
+  ret i1 %r
+}
-- 
2.7.4