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[InstCombine] add tests for rotates with narrow shift amount (PR20750); NFC 

llvm-svn: 360601
This commit is contained in:
Sanjay Patel 2019-05-13 17:02:26 +00:00
parent 69a3f9e465
commit cb8957f718
1 changed files with 46 additions and 0 deletions
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46
llvm/test/Transforms/InstCombine/rotate.ll
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@ -703,3 +703,49 @@ define i32 @rotl_constant_expr(i32 %shamt) {
%r = or i32 %shr, shl (i32 ptrtoint (i8* @external_global to i32), i32 11)
ret i32 %r
}
; PR20750 - https://bugs.llvm.org/show_bug.cgi?id=20750
; This IR corresponds to C source where the shift amount is a smaller type than the rotated value:
; unsigned int rotate32_doubleand1(unsigned int v, unsigned char r) { r = r & 31; return (v << r) | (v >> (((32 - r)) & 31)); }
define i32 @rotateleft32_doubleand1(i32 %v, i8 %r) {
; CHECK-LABEL: @rotateleft32_doubleand1(
; CHECK-NEXT: [[M:%.*]] = and i8 [[R:%.*]], 31
; CHECK-NEXT: [[Z:%.*]] = zext i8 [[M]] to i32
; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[Z]]
; CHECK-NEXT: [[AND2:%.*]] = and i32 [[NEG]], 31
; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[V:%.*]], [[Z]]
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 [[V]], [[AND2]]
; CHECK-NEXT: [[OR:%.*]] = or i32 [[SHR]], [[SHL]]
; CHECK-NEXT: ret i32 [[OR]]
;
%m = and i8 %r, 31
%z = zext i8 %m to i32
%neg = sub nsw i32 0, %z
%and2 = and i32 %neg, 31
%shl = shl i32 %v, %z
%shr = lshr i32 %v, %and2
%or = or i32 %shr, %shl
ret i32 %or
}
define i32 @rotateright32_doubleand1(i32 %v, i16 %r) {
; CHECK-LABEL: @rotateright32_doubleand1(
; CHECK-NEXT: [[M:%.*]] = and i16 [[R:%.*]], 31
; CHECK-NEXT: [[Z:%.*]] = zext i16 [[M]] to i32
; CHECK-NEXT: [[NEG:%.*]] = sub nsw i32 0, [[Z]]
; CHECK-NEXT: [[AND2:%.*]] = and i32 [[NEG]], 31
; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[V:%.*]], [[AND2]]
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 [[V]], [[Z]]
; CHECK-NEXT: [[OR:%.*]] = or i32 [[SHR]], [[SHL]]
; CHECK-NEXT: ret i32 [[OR]]
;
%m = and i16 %r, 31
%z = zext i16 %m to i32
%neg = sub nsw i32 0, %z
%and2 = and i32 %neg, 31
%shl = shl i32 %v, %and2
%shr = lshr i32 %v, %z
%or = or i32 %shr, %shl
ret i32 %or
}