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llvm/llvm/test/Transforms/InstCombine/canonicalize-shl-lshr-to-masking.ll 

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

; https://bugs.llvm.org/show_bug.cgi?id=37603

; Pattern:
;   x << y >> y
; Should be transformed into:
;   x & (-1 >> y)

; ============================================================================ ;
; Basic positive tests
; ============================================================================ ;

define i32 @positive_samevar(i32 %x, i32 %y) {
; CHECK-LABEL: @positive_samevar(
; CHECK-NEXT:    [[TMP1:%.*]] = lshr i32 -1, [[Y:%.*]]
; CHECK-NEXT:    [[RET:%.*]] = and i32 [[TMP1]], [[X:%.*]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, %y
  %ret = lshr i32 %t0, %y
  ret i32 %ret
}

define i32 @positive_sameconst(i32 %x) {
; CHECK-LABEL: @positive_sameconst(
; CHECK-NEXT:    [[T0:%.*]] = and i32 [[X:%.*]], 134217727
; CHECK-NEXT:    ret i32 [[T0]]
;
  %t0 = shl i32 %x, 5
  %ret = lshr i32 %t0, 5
  ret i32 %ret
}

define i32 @positive_biggerShl(i32 %x) {
; CHECK-LABEL: @positive_biggerShl(
; CHECK-NEXT:    [[TMP1:%.*]] = shl i32 [[X:%.*]], 5
; CHECK-NEXT:    [[RET:%.*]] = and i32 [[TMP1]], 134217696
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 10
  %ret = lshr i32 %t0, 5
  ret i32 %ret
}

define i32 @positive_biggerLshr(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr(
; CHECK-NEXT:    [[TMP1:%.*]] = lshr i32 [[X:%.*]], 5
; CHECK-NEXT:    [[RET:%.*]] = and i32 [[TMP1]], 4194303
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 5
  %ret = lshr i32 %t0, 10
  ret i32 %ret
}

define i32 @positive_biggerLshr_lshrexact(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr_lshrexact(
; CHECK-NEXT:    [[TMP1:%.*]] = lshr exact i32 [[X:%.*]], 5
; CHECK-NEXT:    [[RET:%.*]] = and i32 [[TMP1]], 4194303
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 5
  %ret = lshr exact i32 %t0, 10
  ret i32 %ret
}

; ============================================================================ ;
; NUW on the first shift
; ============================================================================ ;

define i32 @positive_samevar_shlnuw(i32 %x, i32 %y) {
; CHECK-LABEL: @positive_samevar_shlnuw(
; CHECK-NEXT:    ret i32 [[X:%.*]]
;
  %t0 = shl nuw i32 %x, %y
  %ret = lshr i32 %t0, %y ; this one is obviously 'exact'.
  ret i32 %ret
}

define i32 @positive_sameconst_shlnuw(i32 %x) {
; CHECK-LABEL: @positive_sameconst_shlnuw(
; CHECK-NEXT:    ret i32 [[X:%.*]]
;
  %t0 = shl nuw i32 %x, 5
  %ret = lshr i32 %t0, 5 ; this one is obviously 'exact'.
  ret i32 %ret
}

define i32 @positive_biggerShl_shlnuw(i32 %x) {
; CHECK-LABEL: @positive_biggerShl_shlnuw(
; CHECK-NEXT:    [[RET:%.*]] = shl nuw nsw i32 [[X:%.*]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl nuw i32 %x, 10
  %ret = lshr i32 %t0, 5 ; this one is obviously 'exact'.
  ret i32 %ret
}

define i32 @positive_biggerLshr_shlnuw(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr_shlnuw(
; CHECK-NEXT:    [[RET:%.*]] = lshr i32 [[X:%.*]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl nuw i32 %x, 5
  %ret = lshr i32 %t0, 10
  ret i32 %ret
}

define i32 @positive_biggerLshr_shlnuw_lshrexact(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr_shlnuw_lshrexact(
; CHECK-NEXT:    [[RET:%.*]] = lshr exact i32 [[X:%.*]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl nuw i32 %x, 5
  %ret = lshr exact i32 %t0, 10
  ret i32 %ret
}

; ============================================================================ ;
; Vector
; ============================================================================ ;

define <2 x i32> @positive_samevar_vec(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @positive_samevar_vec(
; CHECK-NEXT:    [[TMP1:%.*]] = lshr <2 x i32> <i32 -1, i32 -1>, [[Y:%.*]]
; CHECK-NEXT:    [[RET:%.*]] = and <2 x i32> [[TMP1]], [[X:%.*]]
; CHECK-NEXT:    ret <2 x i32> [[RET]]
;
  %t0 = shl <2 x i32> %x, %y
  %ret = lshr <2 x i32> %t0, %y
  ret <2 x i32> %ret
}

; ============================================================================ ;
; Constant Vectors
; ============================================================================ ;

define <2 x i32> @positive_sameconst_vec(<2 x i32> %x) {
; CHECK-LABEL: @positive_sameconst_vec(
; CHECK-NEXT:    [[T0:%.*]] = and <2 x i32> [[X:%.*]], <i32 134217727, i32 134217727>
; CHECK-NEXT:    ret <2 x i32> [[T0]]
;
  %t0 = shl <2 x i32> %x, <i32 5, i32 5>
  %ret = lshr <2 x i32> %t0, <i32 5, i32 5>
  ret <2 x i32> %ret
}

define <3 x i32> @positive_sameconst_vec_undef0(<3 x i32> %x) {
; CHECK-LABEL: @positive_sameconst_vec_undef0(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 5, i32 5, i32 5>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 undef, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 5, i32 5>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_sameconst_vec_undef1(<3 x i32> %x) {
; CHECK-LABEL: @positive_sameconst_vec_undef1(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 5, i32 5, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 5, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 undef, i32 5>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_sameconst_vec_undef2(<3 x i32> %x) {
; CHECK-LABEL: @positive_sameconst_vec_undef2(
; CHECK-NEXT:    [[RET:%.*]] = and <3 x i32> [[X:%.*]], <i32 134217727, i32 poison, i32 134217727>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 undef, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 undef, i32 5>
  ret <3 x i32> %ret
}

define <2 x i32> @positive_biggerShl_vec(<2 x i32> %x) {
; CHECK-LABEL: @positive_biggerShl_vec(
; CHECK-NEXT:    [[TMP1:%.*]] = shl <2 x i32> [[X:%.*]], <i32 5, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = and <2 x i32> [[TMP1]], <i32 134217696, i32 134217696>
; CHECK-NEXT:    ret <2 x i32> [[RET]]
;
  %t0 = shl <2 x i32> %x, <i32 10, i32 10>
  %ret = lshr <2 x i32> %t0, <i32 5, i32 5>
  ret <2 x i32> %ret
}

define <3 x i32> @positive_biggerShl_vec_undef0(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerShl_vec_undef0(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 10, i32 undef, i32 10>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 5, i32 5, i32 5>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 10, i32 undef, i32 10>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 5, i32 5>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_biggerShl_vec_undef1(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerShl_vec_undef1(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 10, i32 10, i32 10>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 10, i32 10, i32 10>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 undef, i32 5>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_biggerShl_vec_undef2(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerShl_vec_undef2(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 10, i32 undef, i32 10>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 10, i32 undef, i32 10>
  %ret = lshr <3 x i32> %t0, <i32 5, i32 undef, i32 5>
  ret <3 x i32> %ret
}

define <2 x i32> @positive_biggerLshr_vec(<2 x i32> %x) {
; CHECK-LABEL: @positive_biggerLshr_vec(
; CHECK-NEXT:    [[TMP1:%.*]] = lshr <2 x i32> [[X:%.*]], <i32 5, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = and <2 x i32> [[TMP1]], <i32 4194303, i32 4194303>
; CHECK-NEXT:    ret <2 x i32> [[RET]]
;
  %t0 = shl <2 x i32> %x, <i32 5, i32 5>
  %ret = lshr <2 x i32> %t0, <i32 10, i32 10>
  ret <2 x i32> %ret
}

define <3 x i32> @positive_biggerLshr_vec_undef0(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerLshr_vec_undef0(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 10, i32 10, i32 10>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 undef, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 10, i32 10, i32 10>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_biggerLshr_vec_undef1(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerLshr_vec_undef1(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 5, i32 5, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 10, i32 undef, i32 10>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 5, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 10, i32 undef, i32 10>
  ret <3 x i32> %ret
}

define <3 x i32> @positive_biggerLshr_vec_undef2(<3 x i32> %x) {
; CHECK-LABEL: @positive_biggerLshr_vec_undef2(
; CHECK-NEXT:    [[T0:%.*]] = shl <3 x i32> [[X:%.*]], <i32 5, i32 undef, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <3 x i32> [[T0]], <i32 10, i32 undef, i32 10>
; CHECK-NEXT:    ret <3 x i32> [[RET]]
;
  %t0 = shl <3 x i32> %x, <i32 5, i32 undef, i32 5>
  %ret = lshr <3 x i32> %t0, <i32 10, i32 undef, i32 10>
  ret <3 x i32> %ret
}

; ============================================================================ ;
; Positive multi-use tests with constant
; ============================================================================ ;

define i32 @positive_sameconst_multiuse(i32 %x) {
; CHECK-LABEL: @positive_sameconst_multiuse(
; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[X:%.*]], 5
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = and i32 [[X]], 134217727
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 5
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, 5
  ret i32 %ret
}

define i32 @positive_biggerShl_shlnuw_multiuse(i32 %x) {
; CHECK-LABEL: @positive_biggerShl_shlnuw_multiuse(
; CHECK-NEXT:    [[T0:%.*]] = shl nuw i32 [[X:%.*]], 10
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = shl nuw nsw i32 [[X]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl nuw i32 %x, 10
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, 5
  ret i32 %ret
}

define i32 @positive_biggerLshr_shlnuw_multiuse(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr_shlnuw_multiuse(
; CHECK-NEXT:    [[T0:%.*]] = shl nuw i32 [[X:%.*]], 5
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = lshr i32 [[X]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl nuw i32 %x, 5
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, 10
  ret i32 %ret
}

; negative test - don't create extra instructions

define i32 @positive_biggerShl_multiuse_extrainstr(i32 %x) {
; CHECK-LABEL: @positive_biggerShl_multiuse_extrainstr(
; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[X:%.*]], 10
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = lshr exact i32 [[T0]], 5
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 10
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, 5
  ret i32 %ret
}

; negative test - don't create extra instructions

define i32 @positive_biggerLshr_multiuse_extrainstr(i32 %x) {
; CHECK-LABEL: @positive_biggerLshr_multiuse_extrainstr(
; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[X:%.*]], 5
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = lshr i32 [[T0]], 10
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, 5
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, 10
  ret i32 %ret
}

; ============================================================================ ;
; Constant Non-Splat Vectors
; ============================================================================ ;

define <2 x i32> @positive_biggerShl_vec_nonsplat(<2 x i32> %x) {
; CHECK-LABEL: @positive_biggerShl_vec_nonsplat(
; CHECK-NEXT:    [[T0:%.*]] = shl <2 x i32> [[X:%.*]], <i32 5, i32 5>
; CHECK-NEXT:    [[RET:%.*]] = lshr <2 x i32> [[T0]], <i32 5, i32 10>
; CHECK-NEXT:    ret <2 x i32> [[RET]]
;
  %t0 = shl <2 x i32> %x, <i32 5, i32 5>
  %ret = lshr <2 x i32> %t0, <i32 5, i32 10>
  ret <2 x i32> %ret
}

define <2 x i32> @positive_biggerLshl_vec_nonsplat(<2 x i32> %x) {
; CHECK-LABEL: @positive_biggerLshl_vec_nonsplat(
; CHECK-NEXT:    [[T0:%.*]] = shl <2 x i32> [[X:%.*]], <i32 5, i32 10>
; CHECK-NEXT:    [[RET:%.*]] = lshr <2 x i32> [[T0]], <i32 5, i32 5>
; CHECK-NEXT:    ret <2 x i32> [[RET]]
;
  %t0 = shl <2 x i32> %x, <i32 5, i32 10>
  %ret = lshr <2 x i32> %t0, <i32 5, i32 5>
  ret <2 x i32> %ret
}

; ============================================================================ ;
; Negative tests. Should not be folded.
; ============================================================================ ;

define i32 @negative_twovars(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @negative_twovars(
; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    [[RET:%.*]] = lshr i32 [[T0]], [[Z:%.*]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, %y
  %ret = lshr i32 %t0, %z ; $z, not %y
  ret i32 %ret
}

declare void @use32(i32)

; One use only.
define i32 @negative_oneuse(i32 %x, i32 %y) {
; CHECK-LABEL: @negative_oneuse(
; CHECK-NEXT:    [[T0:%.*]] = shl i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    call void @use32(i32 [[T0]])
; CHECK-NEXT:    [[RET:%.*]] = lshr exact i32 [[T0]], [[Y]]
; CHECK-NEXT:    ret i32 [[RET]]
;
  %t0 = shl i32 %x, %y
  call void @use32(i32 %t0)
  %ret = lshr i32 %t0, %y
  ret i32 %ret
}