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| ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -simplifycfg -S | FileCheck %s
; This looks like a normal sign extension, but it's not.
; This comes up in JPEG decoding. This check is really unpredictable,
; so it is likely beneficial to avoid the branch.
define i32 @extend_value(i32 %storage, i32 %nbits) {
; CHECK-LABEL: @extend_value(
; CHECK-NEXT: bb:
; CHECK-NEXT: [[SKIPNBITS:%.*]] = sub i32 32, [[NBITS:%.*]]
; CHECK-NEXT: [[VALUE:%.*]] = lshr i32 [[STORAGE:%.*]], [[SKIPNBITS]]
; CHECK-NEXT: [[SHOULDEXTEND:%.*]] = icmp sgt i32 [[STORAGE]], -1
; CHECK-NEXT: [[HIGHBITMASK:%.*]] = shl nsw i32 -1, [[NBITS]]
; CHECK-NEXT: [[HIGHBITMASKPLUSONE:%.*]] = add nsw i32 [[HIGHBITMASK]], 1
; CHECK-NEXT: [[EXTENDED:%.*]] = add i32 [[HIGHBITMASKPLUSONE]], [[VALUE]]
; CHECK-NEXT: [[RES:%.*]] = select i1 [[SHOULDEXTEND]], i32 [[EXTENDED]], i32 [[VALUE]]
; CHECK-NEXT: ret i32 [[RES]]
;
bb:
%skipnbits = sub i32 32, %nbits
%value = lshr i32 %storage, %skipnbits
%shouldextend = icmp sgt i32 %storage, -1
br i1 %shouldextend, label %extend, label %end
extend: ; preds = %bb
%highbitmask = shl nsw i32 -1, %nbits
%highbitmaskplusone = add nsw i32 %highbitmask, 1
%extended = add i32 %highbitmaskplusone, %value
br label %end
end: ; preds = %extend, %bb
%res = phi i32 [ %extended, %extend ], [ %value, %bb ]
ret i32 %res
}
|