llvm/test/Analysis/ScalarEvolution/rounding-demanded-bits.ll

; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6
; RUN: opt < %s "-passes=print<scalar-evolution>" -disable-output 2>&1 | FileCheck %s

; Check that, when constructing a SCEV for rounding a value up to the nearest
; multiple of a constant, we always use that largest possible value for the
; added constant, even if instcombine has cleared some bits in the IR because
; the input is already known to be a multiple of some smaller value.

define i32 @mul_2_round_to_16_a(i32 %val) {
; CHECK-LABEL: 'mul_2_round_to_16_a'
; CHECK-NEXT:  Classifying expressions for: @mul_2_round_to_16_a
; CHECK-NEXT:    %mul = mul i32 %val, 2
; CHECK-NEXT:    --> (2 * %val) U: [0,-1) S: [-2147483648,2147483647)
; CHECK-NEXT:    %add = add i32 %mul, 15
; CHECK-NEXT:    --> (15 + (2 * %val)) U: [15,14) S: [-2147483633,-2147483634)
; CHECK-NEXT:    %round = and i32 %add, -16
; CHECK-NEXT:    --> (16 * ((15 + (2 * %val)) /u 16))<nuw> U: [0,-15) S: [-2147483648,2147483633)
; CHECK-NEXT:  Determining loop execution counts for: @mul_2_round_to_16_a
;
  %mul = mul i32 %val, 2
  %add = add i32 %mul, 15
  %round = and i32 %add, -16
  ret i32 %round
}

define i32 @mul_2_round_to_16_b(i32 %val) {
; CHECK-LABEL: 'mul_2_round_to_16_b'
; CHECK-NEXT:  Classifying expressions for: @mul_2_round_to_16_b
; CHECK-NEXT:    %mul = mul i32 %val, 2
; CHECK-NEXT:    --> (2 * %val) U: [0,-1) S: [-2147483648,2147483647)
; CHECK-NEXT:    %add = add i32 %mul, 14
; CHECK-NEXT:    --> (14 + (2 * %val)) U: [0,-1) S: [-2147483648,2147483647)
; CHECK-NEXT:    %round = and i32 %add, -16
; CHECK-NEXT:    --> (16 * ((15 + (2 * %val)) /u 16))<nuw> U: [0,-15) S: [-2147483648,2147483633)
; CHECK-NEXT:  Determining loop execution counts for: @mul_2_round_to_16_b
;
  %mul = mul i32 %val, 2
  %add = add i32 %mul, 14
  %round = and i32 %add, -16
  ret i32 %round
}

define i32 @mul_2_round_to_16_c(i32 %val) {
; CHECK-LABEL: 'mul_2_round_to_16_c'
; CHECK-NEXT:  Classifying expressions for: @mul_2_round_to_16_c
; CHECK-NEXT:    %mul = mul i32 %val, 2
; CHECK-NEXT:    --> (2 * %val) U: [0,-1) S: [-2147483648,2147483647)
; CHECK-NEXT:    %add = add i32 %mul, 14
; CHECK-NEXT:    --> (14 + (2 * %val)) U: [0,-1) S: [-2147483648,2147483647)
; CHECK-NEXT:    %div = udiv i32 %add, 16
; CHECK-NEXT:    --> ((15 + (2 * %val)) /u 16) U: [0,268435456) S: [0,268435456)
; CHECK-NEXT:    %round = mul i32 %div, 16
; CHECK-NEXT:    --> (16 * ((15 + (2 * %val)) /u 16))<nuw> U: [0,-15) S: [-2147483648,2147483633)
; CHECK-NEXT:  Determining loop execution counts for: @mul_2_round_to_16_c
;
  %mul = mul i32 %val, 2
  %add = add i32 %mul, 14
  %div  = udiv i32 %add, 16
  %round = mul i32 %div, 16
  ret i32 %round
}

define i32 @mul_4_round_to_16(i32 %val) {
; CHECK-LABEL: 'mul_4_round_to_16'
; CHECK-NEXT:  Classifying expressions for: @mul_4_round_to_16
; CHECK-NEXT:    %mul = mul i32 %val, 4
; CHECK-NEXT:    --> (4 * %val) U: [0,-3) S: [-2147483648,2147483645)
; CHECK-NEXT:    %add = add i32 %mul, 12
; CHECK-NEXT:    --> (12 + (4 * %val)) U: [0,-3) S: [-2147483648,2147483645)
; CHECK-NEXT:    %round = and i32 %add, -16
; CHECK-NEXT:    --> (16 * ((15 + (4 * %val)) /u 16))<nuw> U: [0,-15) S: [-2147483648,2147483633)
; CHECK-NEXT:  Determining loop execution counts for: @mul_4_round_to_16
;
  %mul = mul i32 %val, 4
  %add = add i32 %mul, 12
  %round = and i32 %add, -16
  ret i32 %round
}

; N is not a power of 2, cannot do transformation
define i32 @invalid1(i32 %val) {
; CHECK-LABEL: 'invalid1'
; CHECK-NEXT:  Classifying expressions for: @invalid1
; CHECK-NEXT:    %mul = mul i32 %val, 3
; CHECK-NEXT:    --> (3 * %val) U: full-set S: full-set
; CHECK-NEXT:    %add = add i32 %mul, 7
; CHECK-NEXT:    --> (7 + (3 * %val)) U: full-set S: full-set
; CHECK-NEXT:    %div = udiv i32 %add, 9
; CHECK-NEXT:    --> ((7 + (3 * %val)) /u 9) U: [0,477218589) S: [0,477218589)
; CHECK-NEXT:    %round = mul i32 %div, 9
; CHECK-NEXT:    --> (9 * ((7 + (3 * %val)) /u 9))<nuw> U: [0,-3) S: [0,-3)
; CHECK-NEXT:  Determining loop execution counts for: @invalid1
;
  %mul = mul i32 %val, 3
  %add = add i32 %mul, 7
  %div = udiv i32 %add, 9
  %round = mul i32 %div, 9
  ret i32 %round
}

; M is greater then N, cannot do transformation
define i32 @invalid2(i32 %val) {
; CHECK-LABEL: 'invalid2'
; CHECK-NEXT:  Classifying expressions for: @invalid2
; CHECK-NEXT:    %mul = mul i32 %val, 4
; CHECK-NEXT:    --> (4 * %val) U: [0,-3) S: [-2147483648,2147483645)
; CHECK-NEXT:    %add = add i32 %mul, 1
; CHECK-NEXT:    --> (1 + (4 * %val))<nuw><nsw> U: [1,-2) S: [-2147483647,2147483646)
; CHECK-NEXT:    %round = and i32 %add, -2
; CHECK-NEXT:    --> (2 * ((1 + (4 * %val))<nuw><nsw> /u 2))<nuw> U: [0,-3) S: [-2147483648,2147483647)
; CHECK-NEXT:  Determining loop execution counts for: @invalid2
;
  %mul = mul i32 %val, 4
  %add = add i32 %mul, 1
  %round = and i32 %add, -2
  ret i32 %round
}