diff options
| -rw-r--r-- | pp.c | 20 | ||||
| -rw-r--r-- | t/op/bop.t | 19 |
2 files changed, 36 insertions, 3 deletions
@@ -1973,6 +1973,22 @@ PP(pp_subtract) #define IV_BITS (IVSIZE * 8) +/* Taking the right operand of bitwise shift operators, returns an int + * indicating the shift amount clipped to the range [-IV_BITS, +IV_BITS]. + */ +static int +S_shift_amount(pTHX_ SV *const svr) +{ + const IV iv = SvIV_nomg(svr); + + /* Note that [INT_MIN, INT_MAX] cannot be used as the clipping bound; + * INT_MIN will cause overflow in "shift = -shift;" in S_{iv,uv}_shift. + */ + if (SvIsUV(svr)) + return SvUVX(svr) > IV_BITS ? IV_BITS : (int)SvUVX(svr); + return iv < -IV_BITS ? -IV_BITS : iv > IV_BITS ? IV_BITS : (int)iv; +} + static UV S_uv_shift(UV uv, int shift, bool left) { if (shift < 0) { @@ -2026,7 +2042,7 @@ PP(pp_left_shift) svr = POPs; svl = TOPs; { - const IV shift = SvIV_nomg(svr); + const int shift = S_shift_amount(aTHX_ svr); if (PL_op->op_private & HINT_INTEGER) { SETi(IV_LEFT_SHIFT(SvIV_nomg(svl), shift)); } @@ -2044,7 +2060,7 @@ PP(pp_right_shift) svr = POPs; svl = TOPs; { - const IV shift = SvIV_nomg(svr); + const int shift = S_shift_amount(aTHX_ svr); if (PL_op->op_private & HINT_INTEGER) { SETi(IV_RIGHT_SHIFT(SvIV_nomg(svl), shift)); } diff --git a/t/op/bop.t b/t/op/bop.t index 31b6531a03..a84992e391 100644 --- a/t/op/bop.t +++ b/t/op/bop.t @@ -18,7 +18,7 @@ BEGIN { # If you find tests are failing, please try adding names to tests to track # down where the failure is, and supply your new names as a patch. # (Just-in-time test naming) -plan tests => 503; +plan tests => 510; # numerics ok ((0xdead & 0xbeef) == 0x9ead); @@ -40,6 +40,23 @@ ok ((~0 > 0 && do { use integer; ~0 } == -1)); is($shifted, $iv_min, "IV_MIN << 0 yields IV_MIN under 'use integer'"); } +# GH #18691 +# Exercise some corner cases on shifting more bits than the size of IV/UV. +# All these should work even if the shift amount doesn't fit in IV or UV. +is(4 << 2147483648, 0, "4 << 2147483648 yields 0"); +is(16 << 4294967295, 0, "16 << 4294967295 yields 0"); +is(8 >> 4294967296, 0, "8 >> 4294967296 yields 0"); +is(11 << 18446744073709551615, 0, "11 << 18446744073709551615 yields 0"); +is(do { use integer; -9 >> 18446744073709551616 }, -1, + "-9 >> 18446744073709551616 under 'use integer' yields -1"); +is(do { use integer; -4 << -2147483648 }, -1, + "-4 << -2147483648 under 'use integer' yields -1"); +# Quotes around -9223372036854775808 below are to make it a single term. +# Without quotes, it will be parsed as an expression with an unary minus +# operator which will clip the result to IV range under "use integer". +is(do { use integer; -5 >> '-9223372036854775808' }, 0, + "-5 >> -9223372036854775808 under 'use integer' yields 0"); + my $bits = 0; for (my $i = ~0; $i; $i >>= 1) { ++$bits; } my $cusp = 1 << ($bits - 1); |