766cf7f32e
Div/rem by zero is immediate undefined behavior and anything goes. Currently we fold it to undef, this patch changes it to fold to poison instead, which is slightly stronger. Differential Revision: https://reviews.llvm.org/D93995
230 lines
5.9 KiB
LLVM
230 lines
5.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -instsimplify -S | FileCheck %s
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define i32 @zero_dividend(i32 %A) {
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; CHECK-LABEL: @zero_dividend(
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; CHECK-NEXT: ret i32 0
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;
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%B = sdiv i32 0, %A
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ret i32 %B
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}
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define <2 x i32> @zero_dividend_vector(<2 x i32> %A) {
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; CHECK-LABEL: @zero_dividend_vector(
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; CHECK-NEXT: ret <2 x i32> zeroinitializer
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;
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%B = udiv <2 x i32> zeroinitializer, %A
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ret <2 x i32> %B
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}
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define <2 x i32> @zero_dividend_vector_undef_elt(<2 x i32> %A) {
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; CHECK-LABEL: @zero_dividend_vector_undef_elt(
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; CHECK-NEXT: ret <2 x i32> zeroinitializer
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;
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%B = sdiv <2 x i32> <i32 0, i32 undef>, %A
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ret <2 x i32> %B
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}
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; Division-by-zero is poison. UB in any vector lane means the whole op is poison.
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define <2 x i8> @sdiv_zero_elt_vec_constfold(<2 x i8> %x) {
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; CHECK-LABEL: @sdiv_zero_elt_vec_constfold(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = sdiv <2 x i8> <i8 1, i8 2>, <i8 0, i8 -42>
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ret <2 x i8> %div
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}
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define <2 x i8> @udiv_zero_elt_vec_constfold(<2 x i8> %x) {
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; CHECK-LABEL: @udiv_zero_elt_vec_constfold(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = udiv <2 x i8> <i8 1, i8 2>, <i8 42, i8 0>
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ret <2 x i8> %div
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}
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define <2 x i8> @sdiv_zero_elt_vec(<2 x i8> %x) {
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; CHECK-LABEL: @sdiv_zero_elt_vec(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = sdiv <2 x i8> %x, <i8 -42, i8 0>
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ret <2 x i8> %div
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}
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define <2 x i8> @udiv_zero_elt_vec(<2 x i8> %x) {
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; CHECK-LABEL: @udiv_zero_elt_vec(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = udiv <2 x i8> %x, <i8 0, i8 42>
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ret <2 x i8> %div
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}
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define <2 x i8> @sdiv_undef_elt_vec(<2 x i8> %x) {
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; CHECK-LABEL: @sdiv_undef_elt_vec(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = sdiv <2 x i8> %x, <i8 -42, i8 undef>
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ret <2 x i8> %div
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}
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define <2 x i8> @udiv_undef_elt_vec(<2 x i8> %x) {
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; CHECK-LABEL: @udiv_undef_elt_vec(
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; CHECK-NEXT: ret <2 x i8> poison
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;
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%div = udiv <2 x i8> %x, <i8 undef, i8 42>
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ret <2 x i8> %div
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}
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; Division-by-zero is undef. UB in any vector lane means the whole op is undef.
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; Thus, we can simplify this: if any element of 'y' is 0, we can do anything.
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; Therefore, assume that all elements of 'y' must be 1.
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define <2 x i1> @sdiv_bool_vec(<2 x i1> %x, <2 x i1> %y) {
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; CHECK-LABEL: @sdiv_bool_vec(
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; CHECK-NEXT: ret <2 x i1> [[X:%.*]]
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;
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%div = sdiv <2 x i1> %x, %y
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ret <2 x i1> %div
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}
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define <2 x i1> @udiv_bool_vec(<2 x i1> %x, <2 x i1> %y) {
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; CHECK-LABEL: @udiv_bool_vec(
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; CHECK-NEXT: ret <2 x i1> [[X:%.*]]
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;
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%div = udiv <2 x i1> %x, %y
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ret <2 x i1> %div
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}
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define i32 @zext_bool_udiv_divisor(i1 %x, i32 %y) {
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; CHECK-LABEL: @zext_bool_udiv_divisor(
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; CHECK-NEXT: ret i32 [[Y:%.*]]
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;
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%ext = zext i1 %x to i32
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%r = udiv i32 %y, %ext
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ret i32 %r
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}
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define <2 x i32> @zext_bool_sdiv_divisor_vec(<2 x i1> %x, <2 x i32> %y) {
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; CHECK-LABEL: @zext_bool_sdiv_divisor_vec(
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; CHECK-NEXT: ret <2 x i32> [[Y:%.*]]
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;
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%ext = zext <2 x i1> %x to <2 x i32>
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%r = sdiv <2 x i32> %y, %ext
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ret <2 x i32> %r
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}
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define i32 @udiv_dividend_known_smaller_than_constant_divisor(i32 %x) {
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; CHECK-LABEL: @udiv_dividend_known_smaller_than_constant_divisor(
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; CHECK-NEXT: ret i32 0
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;
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%and = and i32 %x, 250
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%div = udiv i32 %and, 251
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ret i32 %div
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}
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define i32 @not_udiv_dividend_known_smaller_than_constant_divisor(i32 %x) {
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; CHECK-LABEL: @not_udiv_dividend_known_smaller_than_constant_divisor(
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; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 251
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; CHECK-NEXT: [[DIV:%.*]] = udiv i32 [[AND]], 251
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; CHECK-NEXT: ret i32 [[DIV]]
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;
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%and = and i32 %x, 251
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%div = udiv i32 %and, 251
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ret i32 %div
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}
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define i32 @udiv_constant_dividend_known_smaller_than_divisor(i32 %x) {
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; CHECK-LABEL: @udiv_constant_dividend_known_smaller_than_divisor(
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; CHECK-NEXT: ret i32 0
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;
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%or = or i32 %x, 251
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%div = udiv i32 250, %or
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ret i32 %div
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}
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define i32 @not_udiv_constant_dividend_known_smaller_than_divisor(i32 %x) {
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; CHECK-LABEL: @not_udiv_constant_dividend_known_smaller_than_divisor(
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; CHECK-NEXT: [[OR:%.*]] = or i32 [[X:%.*]], 251
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; CHECK-NEXT: [[DIV:%.*]] = udiv i32 251, [[OR]]
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; CHECK-NEXT: ret i32 [[DIV]]
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;
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%or = or i32 %x, 251
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%div = udiv i32 251, %or
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ret i32 %div
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}
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; This would require computing known bits on both x and y. Is it worth doing?
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define i32 @udiv_dividend_known_smaller_than_divisor(i32 %x, i32 %y) {
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; CHECK-LABEL: @udiv_dividend_known_smaller_than_divisor(
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; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 250
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; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], 251
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; CHECK-NEXT: [[DIV:%.*]] = udiv i32 [[AND]], [[OR]]
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; CHECK-NEXT: ret i32 [[DIV]]
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;
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%and = and i32 %x, 250
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%or = or i32 %y, 251
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%div = udiv i32 %and, %or
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ret i32 %div
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}
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define i32 @not_udiv_dividend_known_smaller_than_divisor(i32 %x, i32 %y) {
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; CHECK-LABEL: @not_udiv_dividend_known_smaller_than_divisor(
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; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 251
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; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], 251
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; CHECK-NEXT: [[DIV:%.*]] = udiv i32 [[AND]], [[OR]]
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; CHECK-NEXT: ret i32 [[DIV]]
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;
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%and = and i32 %x, 251
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%or = or i32 %y, 251
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%div = udiv i32 %and, %or
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ret i32 %div
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}
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declare i32 @external()
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define i32 @div1() {
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; CHECK-LABEL: @div1(
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; CHECK-NEXT: [[CALL:%.*]] = call i32 @external(), [[RNG0:!range !.*]]
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; CHECK-NEXT: ret i32 0
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;
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%call = call i32 @external(), !range !0
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%urem = udiv i32 %call, 3
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ret i32 %urem
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}
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define i8 @sdiv_minusone_divisor() {
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; CHECK-LABEL: @sdiv_minusone_divisor(
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; CHECK-NEXT: ret i8 poison
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;
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%v = sdiv i8 -128, -1
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ret i8 %v
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}
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define i32 @poison(i32 %x) {
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; CHECK-LABEL: @poison(
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; CHECK-NEXT: ret i32 poison
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;
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%v = udiv i32 %x, poison
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ret i32 %v
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}
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; TODO: this should be poison
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define i32 @poison2(i32 %x) {
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; CHECK-LABEL: @poison2(
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; CHECK-NEXT: ret i32 0
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;
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%v = udiv i32 poison, %x
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ret i32 %v
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}
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define <2 x i32> @poison3(<2 x i32> %x) {
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; CHECK-LABEL: @poison3(
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; CHECK-NEXT: ret <2 x i32> poison
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;
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%v = udiv <2 x i32> %x, <i32 poison, i32 1>
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ret <2 x i32> %v
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}
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!0 = !{i32 0, i32 3}
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