llvm/test/Transforms/InstCombine/shift-shift.ll

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

declare void @use8(i8)
declare void @use32(i32)

; These would crash if we didn't check for a negative shift.

; https://llvm.org/bugs/show_bug.cgi?id=12967

define void @pr12967() {
; CHECK-LABEL: @pr12967(
; CHECK-NEXT:  entry:
; CHECK-NEXT:    br label [[LOOP:%.*]]
; CHECK:       loop:
; CHECK-NEXT:    br label [[LOOP]]
;
entry:
  br label %loop

loop:
  %c = phi i32 [ %shl, %loop ], [ undef, %entry ]
  %shr = shl i32 %c, 7
  %shl = lshr i32 %shr, -2
  br label %loop
}

; https://llvm.org/bugs/show_bug.cgi?id=26760

define void @pr26760() {
; CHECK-LABEL: @pr26760(
; CHECK-NEXT:  entry:
; CHECK-NEXT:    br label [[LOOP:%.*]]
; CHECK:       loop:
; CHECK-NEXT:    br label [[LOOP]]
;
entry:
  br label %loop

loop:
  %c = phi i32 [ %shl, %loop ], [ undef, %entry ]
  %shr = lshr i32 %c, 7
  %shl = shl i32 %shr, -2
  br label %loop
}

; Converting the 2 shifts to SHL 6 without the AND is wrong.
; https://llvm.org/bugs/show_bug.cgi?id=8547

define i32 @pr8547(i32* %g) {
; CHECK-LABEL: @pr8547(
; CHECK-NEXT:  codeRepl:
; CHECK-NEXT:    br label [[FOR_COND:%.*]]
; CHECK:       for.cond:
; CHECK-NEXT:    [[STOREMERGE:%.*]] = phi i32 [ 0, [[CODEREPL:%.*]] ], [ 5, [[FOR_COND]] ]
; CHECK-NEXT:    store i32 [[STOREMERGE]], i32* [[G:%.*]], align 4
; CHECK-NEXT:    [[TMP0:%.*]] = shl nuw nsw i32 [[STOREMERGE]], 6
; CHECK-NEXT:    [[CONV2:%.*]] = and i32 [[TMP0]], 64
; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[CONV2]], 0
; CHECK-NEXT:    br i1 [[TOBOOL]], label [[FOR_COND]], label [[CODEREPL2:%.*]]
; CHECK:       codeRepl2:
; CHECK-NEXT:    ret i32 [[CONV2]]
;
codeRepl:
  br label %for.cond

for.cond:
  %storemerge = phi i32 [ 0, %codeRepl ], [ 5, %for.cond ]
  store i32 %storemerge, i32* %g, align 4
  %shl = shl i32 %storemerge, 30
  %conv2 = lshr i32 %shl, 24
  %tobool = icmp eq i32 %conv2, 0
  br i1 %tobool, label %for.cond, label %codeRepl2

codeRepl2:
  ret i32 %conv2
}

; Two same direction shifts that add up to more than the bitwidth should get
; folded to zero.

define i32 @shl_shl(i32 %A) {
; CHECK-LABEL: @shl_shl(
; CHECK-NEXT:    ret i32 0
;
  %B = shl i32 %A, 6
  %C = shl i32 %B, 28
  ret i32 %C
}

define <2 x i33> @shl_shl_splat_vec(<2 x i33> %A) {
; CHECK-LABEL: @shl_shl_splat_vec(
; CHECK-NEXT:    ret <2 x i33> zeroinitializer
;
  %B = shl <2 x i33> %A, <i33 5, i33 5>
  %C = shl <2 x i33> %B, <i33 28, i33 28>
  ret <2 x i33> %C
}

; FIXME

define <2 x i33> @shl_shl_vec(<2 x i33> %A) {
; CHECK-LABEL: @shl_shl_vec(
; CHECK-NEXT:    [[B:%.*]] = shl <2 x i33> [[A:%.*]], <i33 6, i33 5>
; CHECK-NEXT:    [[C:%.*]] = shl <2 x i33> [[B]], <i33 27, i33 28>
; CHECK-NEXT:    ret <2 x i33> [[C]]
;
  %B = shl <2 x i33> %A, <i33 6, i33 5>
  %C = shl <2 x i33> %B, <i33 27, i33 28>
  ret <2 x i33> %C
}

define i232 @lshr_lshr(i232 %A) {
; CHECK-LABEL: @lshr_lshr(
; CHECK-NEXT:    ret i232 0
;
  %B = lshr i232 %A, 231
  %C = lshr i232 %B, 1
  ret i232 %C
}

define <2 x i32> @lshr_lshr_splat_vec(<2 x i32> %A) {
; CHECK-LABEL: @lshr_lshr_splat_vec(
; CHECK-NEXT:    ret <2 x i32> zeroinitializer
;
  %B = lshr <2 x i32> %A, <i32 28, i32 28>
  %C = lshr <2 x i32> %B, <i32 4, i32 4>
  ret <2 x i32> %C
}

define <2 x i32> @lshr_lshr_vec(<2 x i32> %A) {
; CHECK-LABEL: @lshr_lshr_vec(
; CHECK-NEXT:    ret <2 x i32> zeroinitializer
;
  %B = lshr <2 x i32> %A, <i32 29, i32 28>
  %C = lshr <2 x i32> %B, <i32 4, i32 5>
  ret <2 x i32> %C
}

define i8 @shl_trunc_bigger_lshr(i32 %x) {
; CHECK-LABEL: @shl_trunc_bigger_lshr(
; CHECK-NEXT:    [[SH_DIFF:%.*]] = lshr i32 [[X:%.*]], 2
; CHECK-NEXT:    [[TR_SH_DIFF:%.*]] = trunc i32 [[SH_DIFF]] to i8
; CHECK-NEXT:    [[LT:%.*]] = and i8 [[TR_SH_DIFF]], -8
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 5
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 3
  ret i8 %lt
}

define i8 @shl_trunc_smaller_lshr(i32 %x) {
; CHECK-LABEL: @shl_trunc_smaller_lshr(
; CHECK-NEXT:    [[X_TR:%.*]] = trunc i32 [[X:%.*]] to i8
; CHECK-NEXT:    [[TR_SH_DIFF:%.*]] = shl i8 [[X_TR]], 2
; CHECK-NEXT:    [[LT:%.*]] = and i8 [[TR_SH_DIFF]], -32
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 3
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 5
  ret i8 %lt
}

define i24 @shl_trunc_bigger_ashr(i32 %x) {
; CHECK-LABEL: @shl_trunc_bigger_ashr(
; CHECK-NEXT:    [[SH_DIFF:%.*]] = ashr i32 [[X:%.*]], 9
; CHECK-NEXT:    [[TR_SH_DIFF:%.*]] = trunc i32 [[SH_DIFF]] to i24
; CHECK-NEXT:    [[LT:%.*]] = and i24 [[TR_SH_DIFF]], -8
; CHECK-NEXT:    ret i24 [[LT]]
;
  %rt = ashr i32 %x, 12
  %tr = trunc i32 %rt to i24
  %lt = shl i24 %tr, 3
  ret i24 %lt
}

define i24 @shl_trunc_smaller_ashr(i32 %x) {
; CHECK-LABEL: @shl_trunc_smaller_ashr(
; CHECK-NEXT:    [[X_TR:%.*]] = trunc i32 [[X:%.*]] to i24
; CHECK-NEXT:    [[TR_SH_DIFF:%.*]] = shl i24 [[X_TR]], 3
; CHECK-NEXT:    [[LT:%.*]] = and i24 [[TR_SH_DIFF]], -8192
; CHECK-NEXT:    ret i24 [[LT]]
;
  %rt = ashr i32 %x, 10
  %tr = trunc i32 %rt to i24
  %lt = shl i24 %tr, 13
  ret i24 %lt
}

define i8 @shl_trunc_bigger_shl(i32 %x) {
; CHECK-LABEL: @shl_trunc_bigger_shl(
; CHECK-NEXT:    [[X_TR:%.*]] = trunc i32 [[X:%.*]] to i8
; CHECK-NEXT:    [[TR:%.*]] = shl i8 [[X_TR]], 6
; CHECK-NEXT:    ret i8 [[TR]]
;
  %rt = shl i32 %x, 4
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 2
  ret i8 %lt
}

define i8 @shl_trunc_smaller_shl(i32 %x) {
; CHECK-LABEL: @shl_trunc_smaller_shl(
; CHECK-NEXT:    [[X_TR:%.*]] = trunc i32 [[X:%.*]] to i8
; CHECK-NEXT:    [[TR:%.*]] = shl i8 [[X_TR]], 6
; CHECK-NEXT:    ret i8 [[TR]]
;
  %rt = shl i32 %x, 2
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 4
  ret i8 %lt
}

define i8 @shl_trunc_bigger_lshr_use1(i32 %x) {
; CHECK-LABEL: @shl_trunc_bigger_lshr_use1(
; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 5
; CHECK-NEXT:    call void @use32(i32 [[RT]])
; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 3
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 5
  call void @use32(i32 %rt)
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 3
  ret i8 %lt
}

define i8 @shl_trunc_smaller_lshr_use1(i32 %x) {
; CHECK-LABEL: @shl_trunc_smaller_lshr_use1(
; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 3
; CHECK-NEXT:    call void @use32(i32 [[RT]])
; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 5
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 3
  call void @use32(i32 %rt)
  %tr = trunc i32 %rt to i8
  %lt = shl i8 %tr, 5
  ret i8 %lt
}

define i8 @shl_trunc_bigger_lshr_use2(i32 %x) {
; CHECK-LABEL: @shl_trunc_bigger_lshr_use2(
; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 5
; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
; CHECK-NEXT:    call void @use8(i8 [[TR]])
; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 3
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 5
  %tr = trunc i32 %rt to i8
  call void @use8(i8 %tr)
  %lt = shl i8 %tr, 3
  ret i8 %lt
}

define i8 @shl_trunc_smaller_lshr_use2(i32 %x) {
; CHECK-LABEL: @shl_trunc_smaller_lshr_use2(
; CHECK-NEXT:    [[RT:%.*]] = lshr i32 [[X:%.*]], 3
; CHECK-NEXT:    [[TR:%.*]] = trunc i32 [[RT]] to i8
; CHECK-NEXT:    call void @use8(i8 [[TR]])
; CHECK-NEXT:    [[LT:%.*]] = shl i8 [[TR]], 5
; CHECK-NEXT:    ret i8 [[LT]]
;
  %rt = lshr i32 %x, 3
  %tr = trunc i32 %rt to i8
  call void @use8(i8 %tr)
  %lt = shl i8 %tr, 5
  ret i8 %lt
}