[InstCombine][InstSimplify] Move constant-folding tests in result-of-usub-is-non-zero-and-no-overflow.ll

llvm-svn: 371737

1 files changed, 140 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll b/llvm/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll
new file mode 100644
index 00000000000..66ff797c252
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/result-of-usub-is-non-zero-and-no-overflow.ll
@@ -0,0 +1,140 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instsimplify -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 @use64(i64)
+declare void @use1(i1)
+
+declare void @llvm.assume(i1)
+
+; If we are checking that we either did not get null or got no overflow,
+; this is tautological and is always true.
+
+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:%.*]] = 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 @t1_strict_bad(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t1_strict_bad(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp ugt 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 ugt i8 %base, %offset ; but not for non-strict predicate
+  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 @t1_commutativity(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t1_commutativity(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[NO_UNDERFLOW:%.*]] = icmp ule i8 [[OFFSET]], [[BASE]]
+; 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 ule i8 %offset, %base
+  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
+}
+
+; Likewise, if we are checking that we both got null and overflow happened,
+; it makes no sense and is always false.
+
+define i1 @t2(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t2(
+; 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 ult i8 %base, %offset
+  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 @t2_nonstrict_bad(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t2_nonstrict_bad(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = icmp uge i8 [[ADJUSTED]], [[BASE]]
+; 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 uge i8 %adjusted, %base ; but not for non-strict predicate
+  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 @t2_commutativity(i8 %base, i8 %offset) {
+; CHECK-LABEL: @t2_commutativity(
+; CHECK-NEXT:    [[ADJUSTED:%.*]] = sub i8 [[BASE:%.*]], [[OFFSET:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[ADJUSTED]])
+; CHECK-NEXT:    [[UNDERFLOW:%.*]] = icmp ugt i8 [[OFFSET]], [[BASE]]
+; 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 %offset, %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
+}