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[InstCombine] add tests/comments for negate+sdiv; NFC

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llvm-svn: 358003
This commit is contained in:
Sanjay Patel 2019-04-09 13:41:29 +00:00
parent 6c3ce27efe
commit 57a673c7f9
1 changed files with 35 additions and 0 deletions
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35
test/Transforms/InstCombine/div.ll
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@ -780,6 +780,20 @@ define <2 x i64> @test_exact_vec(<2 x i64> %x) {
ret <2 x i64> %neg
}
; Constant is safe to negate.
define <2 x i8> @negate_sdiv_vec_splat(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_splat(
; CHECK-NEXT: [[NEG:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 -42, i8 -42>
; CHECK-NEXT: ret <2 x i8> [[NEG]]
;
%div = sdiv <2 x i8> %x, <i8 42, i8 42>
%neg = sub <2 x i8> zeroinitializer, %div
ret <2 x i8> %neg
}
; Dividing by undef is UB.
define <2 x i8> @negate_sdiv_vec_undef_elt(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_undef_elt(
; CHECK-NEXT: ret <2 x i8> undef
@ -789,6 +803,8 @@ define <2 x i8> @negate_sdiv_vec_undef_elt(<2 x i8> %x) {
ret <2 x i8> %neg
}
; Division by -1 may be UB (if numerator is the signed min val), but div-by-1 can be simplified.
define <2 x i8> @negate_sdiv_vec_splat_one(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_splat_one(
; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[X:%.*]]
@ -799,6 +815,8 @@ define <2 x i8> @negate_sdiv_vec_splat_one(<2 x i8> %x) {
ret <2 x i8> %neg
}
; Can't negate signed-min constant, but can convert to a compare..
define <2 x i8> @negate_sdiv_vec_splat_signed_min(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_splat_signed_min(
; CHECK-NEXT: [[TMP1:%.*]] = icmp eq <2 x i8> [[X:%.*]], <i8 -128, i8 -128>
@ -810,6 +828,8 @@ define <2 x i8> @negate_sdiv_vec_splat_signed_min(<2 x i8> %x) {
ret <2 x i8> %neg
}
; Division by -1 may be UB for any element of a vector.
define <2 x i8> @negate_sdiv_vec_one_element(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_one_element(
; CHECK-NEXT: [[NEG:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 1, i8 -1>
@ -820,6 +840,8 @@ define <2 x i8> @negate_sdiv_vec_one_element(<2 x i8> %x) {
ret <2 x i8> %neg
}
; Division by -1 may be UB and can't negate signed-min.
define <2 x i8> @negate_sdiv_vec_signed_min_elt(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_signed_min_elt(
; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 -1, i8 -128>
@ -831,6 +853,19 @@ define <2 x i8> @negate_sdiv_vec_signed_min_elt(<2 x i8> %x) {
ret <2 x i8> %neg
}
; Can't negate signed-min constant for any element of a vector.
define <2 x i8> @negate_sdiv_vec_signed_min_and_one_elt(<2 x i8> %x) {
; CHECK-LABEL: @negate_sdiv_vec_signed_min_and_one_elt(
; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i8> [[X:%.*]], <i8 1, i8 -128>
; CHECK-NEXT: [[NEG:%.*]] = sub <2 x i8> zeroinitializer, [[DIV]]
; CHECK-NEXT: ret <2 x i8> [[NEG]]
;
%div = sdiv <2 x i8> %x, <i8 1, i8 -128>
%neg = sub <2 x i8> zeroinitializer, %div
ret <2 x i8> %neg
}
define i32 @test_exact_nonsw_exact(i32 %x) {
; CHECK-LABEL: @test_exact_nonsw_exact(
; CHECK-NEXT: [[NEG:%.*]] = sdiv exact i32 [[X:%.*]], -3