bool OrOfAnds = match(Op0, m_And(m_Value(), m_Value())) &&
match(Op1, m_And(m_Value(), m_Value()));
- if (!OrOfOrs && !OrOfShifts && !OrOfAnds)
+ // (A << B) | (C & D) -> bswap if possible.
+ // The bigger pattern here is ((A & C1) << C2) | ((B >> C2) & C1), which is a
+ // part of the bswap idiom for specific values of C1, C2 (e.g. C1 = 16711935,
+ // C2 = 8 for i32).
+ // This pattern can occur when the operands of the 'or' are not canonicalized
+ // for some reason (not having only one use, for example).
+ bool OrOfAndAndSh = (match(Op0, m_LogicalShift(m_Value(), m_Value())) &&
+ match(Op1, m_And(m_Value(), m_Value()))) ||
+ (match(Op0, m_And(m_Value(), m_Value())) &&
+ match(Op1, m_LogicalShift(m_Value(), m_Value())));
+
+ if (!OrOfOrs && !OrOfShifts && !OrOfAnds && !OrOfAndAndSh)
return nullptr;
SmallVector<Instruction*, 4> Insts;
ret i32 %bswap
}
-; FIXME: Extra use should not prevent matching to bswap.
+; Extra use should not prevent matching to bswap.
; swaphalf = (x << 16 | x >> 16)
; ((swaphalf & 0x00ff00ff) << 8) | ((swaphalf >> 8) & 0x00ff00ff)
; CHECK-NEXT: [[SHR:%.*]] = lshr i32 %x, 16
; CHECK-NEXT: [[SWAPHALF:%.*]] = or i32 [[SHL]], [[SHR]]
; CHECK-NEXT: [[T:%.*]] = and i32 [[SWAPHALF]], 16711935
-; CHECK-NEXT: [[TSHL:%.*]] = shl nuw i32 [[T]], 8
-; CHECK-NEXT: [[B:%.*]] = lshr i32 [[SWAPHALF]], 8
-; CHECK-NEXT: [[BAND:%.*]] = and i32 [[B]], 16711935
-; CHECK-NEXT: [[BSWAP:%.*]] = or i32 [[TSHL]], [[BAND]]
+; CHECK-NEXT: [[BSWAP:%.*]] = call i32 @llvm.bswap.i32(i32 %x)
; CHECK-NEXT: call void @extra_use(i32 [[T]])
; CHECK-NEXT: ret i32 [[BSWAP]]
;