llvm/test/Analysis/ValueTracking/knownbits-pdep.ll

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

; pdep(x, 0b11110000): bits 0..3 of result are always zero.
define i1 @pdep_low_bits_zero(i8 %x) nounwind {
; CHECK-LABEL: @pdep_low_bits_zero(
; CHECK-NEXT:    ret i1 true
;
  %pdep = call i8 @llvm.pdep.i8(i8 %x, i8 240)
  %and = and i8 %pdep, 15
  %r = icmp eq i8 %and, 0
  ret i1 %r
}

define <2 x i1> @pdep_low_bits_zero_vector(<2 x i8> %x) nounwind {
; CHECK-LABEL: @pdep_low_bits_zero_vector(
; CHECK-NEXT:    ret <2 x i1> splat (i1 true)
;
  %pdep = call <2 x i8> @llvm.pdep.v2i8(<2 x i8> %x, <2 x i8> splat (i8 -16))
  %and = and <2 x i8> %pdep, splat (i8 15)
  %r = icmp eq <2 x i8> %and, zeroinitializer
  ret <2 x i1> %r
}

; pdep(x, 0b00001111): bits 4..7 of result are always zero.
define i1 @pdep_high_bits_zero(i8 %x) nounwind {
; CHECK-LABEL: @pdep_high_bits_zero(
; CHECK-NEXT:    ret i1 true
;
  %pdep = call i8 @llvm.pdep.i8(i8 %x, i8 15)
  %and = and i8 %pdep, 240
  %r = icmp eq i8 %and, 0
  ret i1 %r
}

define <2 x i1> @pdep_high_bits_zero_vector(<2 x i8> %x) nounwind {
; CHECK-LABEL: @pdep_high_bits_zero_vector(
; CHECK-NEXT:    ret <2 x i1> splat (i1 true)
;
  %pdep = call <2 x i8> @llvm.pdep.v2i8(<2 x i8> %x, <2 x i8> splat (i8 15))
  %and = and <2 x i8> %pdep, splat (i8 240)
  %r = icmp eq <2 x i8> %and, zeroinitializer
  ret <2 x i1> %r
}

; pdep(x, 0) -> all bits zero.
define i1 @pdep_zero_mask_known_zero(i8 %x) nounwind {
; CHECK-LABEL: @pdep_zero_mask_known_zero(
; CHECK-NEXT:    ret i1 true
;
  %pdep = call i8 @llvm.pdep.i8(i8 %x, i8 0)
  %r = icmp eq i8 %pdep, 0
  ret i1 %r
}

define <2 x i1> @pdep_zero_mask_known_zero_vector(<2 x i8> %x) nounwind {
; CHECK-LABEL: @pdep_zero_mask_known_zero_vector(
; CHECK-NEXT:    ret <2 x i1> splat (i1 true)
;
  %pdep = call <2 x i8> @llvm.pdep.v2i8(<2 x i8> %x, <2 x i8> zeroinitializer)
  %r = icmp eq <2 x i8> %pdep, zeroinitializer
  ret <2 x i1> %r
}

; Negative: pdep(x, 0b11001100) can have bits 2,3,6,7 set.
; Sign bit may be set, but known bits analysis can narrow the range.
define i1 @pdep_mask_bits_not_known(i8 %x) nounwind {
; CHECK-LABEL: @pdep_mask_bits_not_known(
; CHECK-NEXT:    [[PDEP:%.*]] = call i8 @llvm.pdep.i8(i8 [[X:%.*]], i8 -52)
; CHECK-NEXT:    [[R:%.*]] = icmp sgt i8 [[PDEP]], -1
; CHECK-NEXT:    ret i1 [[R]]
;
  %pdep = call i8 @llvm.pdep.i8(i8 %x, i8 204)
  %and = and i8 %pdep, 128
  %r = icmp eq i8 %and, 0
  ret i1 %r
}

define <2 x i1> @pdep_mask_bits_not_known_vector(<2 x i8> %x) nounwind {
; CHECK-LABEL: @pdep_mask_bits_not_known_vector(
; CHECK-NEXT:    [[PDEP:%.*]] = call <2 x i8> @llvm.pdep.v2i8(<2 x i8> [[X:%.*]], <2 x i8> splat (i8 -52))
; CHECK-NEXT:    [[R:%.*]] = icmp sgt <2 x i8> [[PDEP]], splat (i8 -1)
; CHECK-NEXT:    ret <2 x i1> [[R]]
;
  %pdep = call <2 x i8> @llvm.pdep.v2i8(<2 x i8> %x, <2 x i8> splat (i8 -52))
  %and = and <2 x i8> %pdep, splat (i8 128)
  %r = icmp eq <2 x i8> %and, zeroinitializer
  ret <2 x i1> %r
}