llvm/test/Transforms/InstCombine/compare-signs.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s

; PR5438

define i32 @test1(i32 %a, i32 %b) nounwind readnone {
; CHECK-LABEL: @test1(
; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[B:%.*]], [[A:%.*]]
; CHECK-NEXT:    [[TMP2:%.*]] = xor i32 [[TMP1]], -1
; CHECK-NEXT:    [[DOTLOBIT_NOT:%.*]] = lshr i32 [[TMP2]], 31
; CHECK-NEXT:    ret i32 [[DOTLOBIT_NOT]]
;
  %t0 = icmp sgt i32 %a, -1
  %t1 = icmp slt i32 %b, 0
  %t2 = xor i1 %t1, %t0
  %t3 = zext i1 %t2 to i32
  ret i32 %t3
}

; TODO: This optimizes partially but not all the way.
define i32 @test2(i32 %a, i32 %b) nounwind readnone {
; CHECK-LABEL: @test2(
; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT:    [[TMP2:%.*]] = lshr i32 [[TMP1]], 3
; CHECK-NEXT:    [[DOTLOBIT:%.*]] = and i32 [[TMP2]], 1
; CHECK-NEXT:    [[TMP3:%.*]] = xor i32 [[DOTLOBIT]], 1
; CHECK-NEXT:    ret i32 [[TMP3]]
;
  %t0 = and i32 %a, 8
  %t1 = and i32 %b, 8
  %t2 = icmp eq i32 %t0, %t1
  %t3 = zext i1 %t2 to i32
  ret i32 %t3
}

define i32 @test3(i32 %a, i32 %b) nounwind readnone {
; CHECK-LABEL: @test3(
; CHECK-NEXT:    [[T2_UNSHIFTED:%.*]] = xor i32 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[T2_UNSHIFTED]], -1
; CHECK-NEXT:    [[T2_UNSHIFTED_LOBIT_NOT:%.*]] = lshr i32 [[TMP1]], 31
; CHECK-NEXT:    ret i32 [[T2_UNSHIFTED_LOBIT_NOT]]
;
  %t0 = lshr i32 %a, 31
  %t1 = lshr i32 %b, 31
  %t2 = icmp eq i32 %t0, %t1
  %t3 = zext i1 %t2 to i32
  ret i32 %t3
}

; TODO this should optimize but doesn't due to missing vector support in InstCombiner::foldICmpEquality.
define <2 x i32> @test3vec(<2 x i32> %a, <2 x i32> %b) nounwind readnone {
; CHECK-LABEL: @test3vec(
; CHECK-NEXT:    [[T0:%.*]] = lshr <2 x i32> [[A:%.*]], <i32 31, i32 31>
; CHECK-NEXT:    [[T1:%.*]] = lshr <2 x i32> [[B:%.*]], <i32 31, i32 31>
; CHECK-NEXT:    [[T2:%.*]] = icmp eq <2 x i32> [[T0]], [[T1]]
; CHECK-NEXT:    [[T3:%.*]] = zext <2 x i1> [[T2]] to <2 x i32>
; CHECK-NEXT:    ret <2 x i32> [[T3]]
;
  %t0 = lshr <2 x i32> %a, <i32 31, i32 31>
  %t1 = lshr <2 x i32> %b, <i32 31, i32 31>
  %t2 = icmp eq <2 x i32> %t0, %t1
  %t3 = zext <2 x i1> %t2 to <2 x i32>
  ret <2 x i32> %t3
}

; Variation on @test3: checking the 2nd bit in a situation where the 5th bit
; is one, not zero.
define i32 @test3i(i32 %a, i32 %b) nounwind readnone {
; CHECK-LABEL: @test3i(
; CHECK-NEXT:    [[T01:%.*]] = xor i32 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT:    [[TMP1:%.*]] = xor i32 [[T01]], -1
; CHECK-NEXT:    [[T01_LOBIT_NOT:%.*]] = lshr i32 [[TMP1]], 31
; CHECK-NEXT:    ret i32 [[T01_LOBIT_NOT]]
;
  %t0 = lshr i32 %a, 29
  %t1 = lshr i32 %b, 29
  %t2 = or i32 %t0, 35
  %t3 = or i32 %t1, 35
  %t4 = icmp eq i32 %t2, %t3
  %t5 = zext i1 %t4 to i32
  ret i32 %t5
}

define i1 @test4a(i32 %a) {
; CHECK-LABEL: @test4a(
; CHECK-NEXT:    [[C:%.*]] = icmp slt i32 [[A:%.*]], 1
; CHECK-NEXT:    ret i1 [[C]]
;
  %l = ashr i32 %a, 31
  %na = sub i32 0, %a
  %r = lshr i32 %na, 31
  %signum = or i32 %l, %r
  %c = icmp slt i32 %signum, 1
  ret i1 %c
}

define <2 x i1> @test4a_vec(<2 x i32> %a) {
; CHECK-LABEL: @test4a_vec(
; CHECK-NEXT:    [[C:%.*]] = icmp slt <2 x i32> [[A:%.*]], <i32 1, i32 1>
; CHECK-NEXT:    ret <2 x i1> [[C]]
;
  %l = ashr <2 x i32> %a, <i32 31, i32 31>
  %na = sub <2 x i32> zeroinitializer, %a
  %r = lshr <2 x i32> %na, <i32 31, i32 31>
  %signum = or <2 x i32> %l, %r
  %c = icmp slt <2 x i32> %signum, <i32 1, i32 1>
  ret <2 x i1> %c
}

define i1 @test4b(i64 %a) {
; CHECK-LABEL: @test4b(
; CHECK-NEXT:    [[C:%.*]] = icmp slt i64 [[A:%.*]], 1
; CHECK-NEXT:    ret i1 [[C]]
;
  %l = ashr i64 %a, 63
  %na = sub i64 0, %a
  %r = lshr i64 %na, 63
  %signum = or i64 %l, %r
  %c = icmp slt i64 %signum, 1
  ret i1 %c
}

define i1 @test4c(i64 %a) {
; CHECK-LABEL: @test4c(
; CHECK-NEXT:    [[C:%.*]] = icmp slt i64 [[A:%.*]], 1
; CHECK-NEXT:    ret i1 [[C]]
;
  %l = ashr i64 %a, 63
  %na = sub i64 0, %a
  %r = lshr i64 %na, 63
  %signum = or i64 %l, %r
  %signum.trunc = trunc i64 %signum to i32
  %c = icmp slt i32 %signum.trunc, 1
  ret i1 %c
}

define <2 x i1> @test4c_vec(<2 x i64> %a) {
; CHECK-LABEL: @test4c_vec(
; CHECK-NEXT:    [[C:%.*]] = icmp slt <2 x i64> [[A:%.*]], <i64 1, i64 1>
; CHECK-NEXT:    ret <2 x i1> [[C]]
;
  %l = ashr <2 x i64> %a, <i64 63, i64 63>
  %na = sub <2 x i64> zeroinitializer, %a
  %r = lshr <2 x i64> %na, <i64 63, i64 63>
  %signum = or <2 x i64> %l, %r
  %signum.trunc = trunc <2 x i64> %signum to <2 x i32>
  %c = icmp slt <2 x i32> %signum.trunc, <i32 1, i32 1>
  ret <2 x i1> %c
}

; PR49866

define i1 @shift_trunc_signbit_test(i32 %x) {
; CHECK-LABEL: @shift_trunc_signbit_test(
; CHECK-NEXT:    [[R:%.*]] = icmp slt i32 [[X:%.*]], 0
; CHECK-NEXT:    ret i1 [[R]]
;
  %sh = lshr i32 %x, 24
  %tr = trunc i32 %sh to i8
  %r = icmp slt i8 %tr, 0
  ret i1 %r
}

define <2 x i1> @shift_trunc_signbit_test_vec_uses(<2 x i17> %x, <2 x i17>* %p1, <2 x i13>* %p2) {
; CHECK-LABEL: @shift_trunc_signbit_test_vec_uses(
; CHECK-NEXT:    [[SH:%.*]] = lshr <2 x i17> [[X:%.*]], <i17 4, i17 4>
; CHECK-NEXT:    store <2 x i17> [[SH]], <2 x i17>* [[P1:%.*]], align 8
; CHECK-NEXT:    [[TR:%.*]] = trunc <2 x i17> [[SH]] to <2 x i13>
; CHECK-NEXT:    store <2 x i13> [[TR]], <2 x i13>* [[P2:%.*]], align 4
; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i17> [[X]], <i17 -1, i17 -1>
; CHECK-NEXT:    ret <2 x i1> [[R]]
;
  %sh = lshr <2 x i17> %x, <i17 4, i17 4>
  store <2 x i17> %sh, <2 x i17>* %p1
  %tr = trunc <2 x i17> %sh to <2 x i13>
  store <2 x i13> %tr, <2 x i13>* %p2
  %r = icmp sgt <2 x i13> %tr, <i13 -1, i13 -1>
  ret <2 x i1> %r
}

; negative test - but this reduces with a mask op

define i1 @shift_trunc_wrong_shift(i32 %x) {
; CHECK-LABEL: @shift_trunc_wrong_shift(
; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[X:%.*]], 1073741824
; CHECK-NEXT:    [[R:%.*]] = icmp ne i32 [[TMP1]], 0
; CHECK-NEXT:    ret i1 [[R]]
;
  %sh = lshr i32 %x, 23
  %tr = trunc i32 %sh to i8
  %r = icmp slt i8 %tr, 0
  ret i1 %r
}

; negative test

define i1 @shift_trunc_wrong_cmp(i32 %x) {
; CHECK-LABEL: @shift_trunc_wrong_cmp(
; CHECK-NEXT:    [[SH:%.*]] = lshr i32 [[X:%.*]], 24
; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[SH]] to i8
; CHECK-NEXT:    [[R:%.*]] = icmp slt i8 [[TR]], 1
; CHECK-NEXT:    ret i1 [[R]]
;
  %sh = lshr i32 %x, 24
  %tr = trunc i32 %sh to i8
  %r = icmp slt i8 %tr, 1
  ret i1 %r
}