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

; RUN: opt < %s -instcombine -S | FileCheck %s


define i32 @test1(i32 %X, i8 %A) {
        %shift.upgrd.1 = zext i8 %A to i32              ; <i32> [#uses=1]
        ; can be logical shift.
        %Y = ashr i32 %X, %shift.upgrd.1                ; <i32> [#uses=1]
        %Z = and i32 %Y, 1              ; <i32> [#uses=1]
        ret i32 %Z
; CHECK: @test1
; CHECK: lshr i32 %X, %shift.upgrd.1 
}

define i32 @test2(i8 %tmp) {
        %tmp3 = zext i8 %tmp to i32             ; <i32> [#uses=1]
        %tmp4 = add i32 %tmp3, 7                ; <i32> [#uses=1]
        %tmp5 = ashr i32 %tmp4, 3               ; <i32> [#uses=1]
        ret i32 %tmp5
; CHECK: @test2
; CHECK: lshr i32 %tmp4, 3
}

define i64 @test3(i1 %X, i64 %Y, i1 %Cond) {
  br i1 %Cond, label %T, label %F
T:
  %X2 = sext i1 %X to i64
  br label %C
F:
  %Y2 = ashr i64 %Y, 63
  br label %C
C:
  %P = phi i64 [%X2, %T], [%Y2, %F] 
  %S = ashr i64 %P, 12
  ret i64 %S
  
; CHECK: @test3
; CHECK: %P = phi i64
; CHECK-NEXT: ret i64 %P
}

define i64 @test4(i1 %X, i64 %Y, i1 %Cond) {
  br i1 %Cond, label %T, label %F
T:
  %X2 = sext i1 %X to i64
  br label %C
F:
  %Y2 = ashr i64 %Y, 63
  br label %C
C:
  %P = phi i64 [%X2, %T], [%Y2, %F] 
  %R = shl i64 %P, 12
  %S = ashr i64 %R, 12
  ret i64 %S
  
; CHECK: @test4
; CHECK: %P = phi i64
; CHECK-NEXT: ret i64 %P
}

; rdar://7732987
define i32 @test5(i32 %Y) {
  br i1 undef, label %A, label %C
A:
  br i1 undef, label %B, label %D
B:
  br label %D
C:
  br i1 undef, label %D, label %E
D:
  %P = phi i32 [0, %A], [0, %B], [%Y, %C] 
  %S = ashr i32 %P, 16
  ret i32 %S
; CHECK: @test5
; CHECK: %P = phi i32
; CHECK-NEXT: ashr i32 %P, 16
E:
  ret i32 0
}