Klaus Post <******@****.***> 1457448890 +0100

(Rsh64x64 [c] x (Int64Make (Const32 [0]) lo)) => (Rsh64x32 [c] x lo)
(Rsh64Ux64 [c] x (Int64Make (Const32 [0]) lo)) => (Rsh64Ux32 [c] x lo)

// turn x64 non-constant shifts to x32 shifts
// if high 32-bit of the shift is nonzero, make a huge shift
(Lsh64x64 x (Int64Make hi lo)) && hi.Op != OpConst32 =>
       (Lsh64x32 x (Or32 <typ.UInt32> (Zeromask hi) lo))
(Rsh64x64 x (Int64Make hi lo)) && hi.Op != OpConst32 =>

		// the compiler to generate better code for the shift operation.
		shift := uint(bits.TrailingZeros(uint(base))) & 7
		b := uint64(base)
		m := uint(base) - 1 // == 1<<shift - 1
		for u >= b {
			i--
			a[i] = digits[uint(u)&m]
			u >>= shift
		}
		// u < base
		i--
		a[i] = digits[uint(u)]
	} else {
		// general case
		b := uint64(base)
		for u >= b {
			i--

specified alignment.

6. Shift instructions

The simple scalar shifts on PPC64 expect a shift count that fits in 5 bits for
32-bit values or 6 bit for 64-bit values. If the shift count is a constant value
greater than the max then the assembler sets it to the max for that size (31 for
32 bit values, 63 for 64 bit values). If the shift count is in a register, then

Klaus Post <******@****.***> 1457448890 +0100

	sign = uint32(b >> 63)
	exp = int32(b>>52) & mask
	mantissa = b & fracMask

	if exp == 0 {
		// Normalize value if subnormal.
		shift := uint(bits.LeadingZeros64(mantissa) - 11)
		mantissa <<= shift
		exp = 1 - int32(shift)
	} else {
		// Add implicit 1 bit
		mantissa |= 1 << 52
	}
	return
}

// FMA returns x * y + z, computed with only one rounding.

	if one16<<N<<N == 1 {
		t.Errorf("shift overflow mishandled")
	}
	if one16>>N>>N == 1 {
		t.Errorf("shift overflow mishandled")
	}
	if one16u>>N>>N == 1 {
		t.Errorf("shift overflow mishandled")
	}
	if one8<<N<<N == 1 {
		t.Errorf("shift overflow mishandled")
	}
	if one8>>N>>N == 1 {
		t.Errorf("shift overflow mishandled")
	}
	if one8u>>N>>N == 1 {
		t.Errorf("shift overflow mishandled")
	}
}

	ADDS	R7@>2, R5, R16                                   // ERROR "unsupported shift operator"
	ADDSW	R7@>2, R5, R16                                   // ERROR "unsupported shift operator"
	SUB	R7@>2, R5, R16                                   // ERROR "unsupported shift operator"
	SUBW	R7@>2, R5, R16                                   // ERROR "unsupported shift operator"

			Valu("c", OpConst64, c.config.Types.UInt64, amount, nil),
			Valu("shift", op, typ, 0, nil, "load", "c"),
			Valu("store", OpStore, types.TypeMem, 0, c.config.Types.UInt64, "resptr", "shift", "mem"),
			Exit("store")))
	Compile(fun.f)
	return fun
}

func TestShiftToExtensionAMD64(t *testing.T) {
	c := testConfig(t)
	// Test that eligible pairs of constant shifts are converted to extensions.
	// For example:

		{name: "ANDshiftRAreg", argLength: 3, reg: gp31, asm: "AND"}, // arg0 & (arg1>>arg2), signed shift
		{name: "ORshiftLLreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1<<arg2
		{name: "ORshiftRLreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1>>arg2, unsigned shift
		{name: "ORshiftRAreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1>>arg2, signed shift