Mercurial > vim
changeset 28964:8973f2f00872 v8.2.5004
patch 8.2.5004: right shift on negative number does not work as documented
Commit: https://github.com/vim/vim/commit/338bf58eba758585ffef3fdfdba7d48477aacb7c
Author: Bram Moolenaar <Bram@vim.org>
Date: Sun May 22 20:16:32 2022 +0100
patch 8.2.5004: right shift on negative number does not work as documented
Problem: Right shift on negative number does not work as documented.
Solution: Use a uvarnumber_T type cast.
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Sun, 22 May 2022 21:30:02 +0200 |
| parents | 3759e377a750 |
| children | 28d752b64734 |
| files | runtime/doc/eval.txt src/charset.c src/eval.c src/testdir/test_expr.vim src/version.c src/vim9execute.c src/vim9expr.c |
| diffstat | 7 files changed, 26 insertions(+), 19 deletions(-) [+] |
line wrap: on
line diff
--- a/runtime/doc/eval.txt +++ b/runtime/doc/eval.txt @@ -1138,9 +1138,10 @@ expr6 >> expr6 bitwise right shift *e *E1282* *E1283* The "<<" and ">>" operators can be used to perform bitwise left or right shift of the left operand by the number of bits specified by the right operand. The -operands must be positive numbers. The topmost bit (sign bit) is always -cleared for ">>". If the right operand (shift amount) is more than the -maximum number of bits in a number (|v:numbersize|) the result is zero. +operands are used as positive numbers. When shifting right with ">>" the +topmost bit (somtimes called the sign bit) is cleared. If the right operand +(shift amount) is more than the maximum number of bits in a number +(|v:numbersize|) the result is zero. expr6 and expr7 *expr6* *expr7* *E1036* *E1051* @@ -1417,6 +1418,10 @@ number number constant *expr-number* Decimal, Hexadecimal (starting with 0x or 0X), Binary (starting with 0b or 0B) and Octal (starting with 0, 0o or 0O). +Assuming 64 bit numbers are used (see |v:numbersize|) an unsigned number is +truncated to 0x7fffffffffffffff or 9223372036854775807. You can use -1 to get +0xffffffffffffffff. + *floating-point-format* Floating point numbers can be written in two forms:
--- a/src/charset.c +++ b/src/charset.c @@ -2002,6 +2002,7 @@ vim_str2nr( } else { + // prevent a larg unsigned number to become negative if (un > VARNUM_MAX) un = VARNUM_MAX; *nptr = (varnumber_T)un;
--- a/src/eval.c +++ b/src/eval.c @@ -3091,12 +3091,8 @@ eval5(char_u **arg, typval_T *rettv, eva rettv->vval.v_number = rettv->vval.v_number << var2.vval.v_number; else - { rettv->vval.v_number = - rettv->vval.v_number >> var2.vval.v_number; - // clear the topmost sign bit - rettv->vval.v_number &= ~((uvarnumber_T)1 << MAX_LSHIFT_BITS); - } + (uvarnumber_T)rettv->vval.v_number >> var2.vval.v_number; } clear_tv(&var2);
--- a/src/testdir/test_expr.vim +++ b/src/testdir/test_expr.vim @@ -958,6 +958,8 @@ func Test_bitwise_shift() call assert_equal(0, 0 >> 4) call assert_equal(0, 999999 >> 100) call assert_equal(0, 999999 << 100) + call assert_equal(-1, -1 >> 0) + call assert_equal(-1, -1 << 0) VAR a = 8 VAR b = 2 call assert_equal(2, a >> b) @@ -976,6 +978,15 @@ func Test_bitwise_shift() for i in range(0, v:numbersize - 2) LET val = and(val, invert(1 << i)) endfor + #" -1 has all the bits set + call assert_equal(-2, -1 << 1) + call assert_equal(-4, -1 << 2) + call assert_equal(-8, -1 << 3) + if v:numbersize == 64 + call assert_equal(0x7fffffffffffffff, -1 >> 1) + call assert_equal(0x3fffffffffffffff, -1 >> 2) + call assert_equal(0x1fffffffffffffff, -1 >> 3) + endif call assert_equal(0, val) #" multiple operators call assert_equal(16, 1 << 2 << 2)
--- a/src/version.c +++ b/src/version.c @@ -735,6 +735,8 @@ static char *(features[]) = static int included_patches[] = { /* Add new patch number below this line */ /**/ + 5004, +/**/ 5003, /**/ 5002,
--- a/src/vim9execute.c +++ b/src/vim9execute.c @@ -4096,12 +4096,7 @@ exec_instructions(ectx_T *ectx) case EXPR_RSHIFT: if (arg2 > MAX_LSHIFT_BITS) res = 0; else - { - res = arg1 >> arg2; - // clear the topmost sign bit - res &= ~((uvarnumber_T)1 - << MAX_LSHIFT_BITS); - } + res = (uvarnumber_T)arg1 >> arg2; break; default: break; }
--- a/src/vim9expr.c +++ b/src/vim9expr.c @@ -2719,11 +2719,8 @@ compile_expr5(char_u **arg, cctx_T *cctx else if (type == EXPR_LSHIFT) tv1->vval.v_number = tv1->vval.v_number << tv2->vval.v_number; else - { - tv1->vval.v_number = tv1->vval.v_number >> tv2->vval.v_number; - // clear the topmost sign bit - tv1->vval.v_number &= ~((uvarnumber_T)1 << MAX_LSHIFT_BITS); - } + tv1->vval.v_number = + (uvarnumber_T)tv1->vval.v_number >> tv2->vval.v_number; clear_tv(tv2); --ppconst->pp_used; }