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| author | Jason Merrill <jason@redhat.com> | 2020-01-10 13:53:17 -0500 |
|---|---|---|
| committer | Jason Merrill <jason@gcc.gnu.org> | 2020-01-10 13:53:17 -0500 |
| commit | 337ea6b216afd412b85f3fda78a36467ffe4a817 (patch) | |
| tree | de398d158f61994e8448352cca3d5cddabccf119 /gcc/cp | |
| parent | e0804c9b5efdf17bbfb692a787df36b86f71af8d (diff) | |
| download | gcc-337ea6b216afd412b85f3fda78a36467ffe4a817.zip gcc-337ea6b216afd412b85f3fda78a36467ffe4a817.tar.gz gcc-337ea6b216afd412b85f3fda78a36467ffe4a817.tar.bz2 | |
Shorten right-shift again in C++.
Back in SVN r131862 richi removed this code to fix PR 34235, but didn't
remove the parallel code from the C front-end because the bug had previously
been fixed in r44080. This patch copies the code from C again.
* typeck.c (cp_build_binary_op): Restore short_shift code.
From-SVN: r280128
Diffstat (limited to 'gcc/cp')
| -rw-r--r-- | gcc/cp/ChangeLog | 2 | ||||
| -rw-r--r-- | gcc/cp/typeck.c | 38 |
2 files changed, 40 insertions, 0 deletions
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index 1a36cd3..1dad238 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,5 +1,7 @@ 2020-01-10 Jason Merrill <jason@redhat.com> + * typeck.c (cp_build_binary_op): Restore short_shift code. + PR c++/93143 - incorrect tree sharing with constexpr. * constexpr.c (cxx_eval_outermost_constant_expr): Don't assume CONSTRUCTORs are already unshared. diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index 9f4f535..7b653ceb 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -4452,6 +4452,10 @@ cp_build_binary_op (const op_location_t &location, Also implies COMMON. */ int short_compare = 0; + /* Nonzero if this is a right-shift operation, which can be computed on the + original short and then promoted if the operand is a promoted short. */ + int short_shift = 0; + /* Nonzero means set RESULT_TYPE to the common type of the args. */ int common = 0; @@ -4844,6 +4848,9 @@ cp_build_binary_op (const op_location_t &location, } else { + if (!integer_zerop (op1)) + short_shift = 1; + if (compare_tree_int (const_op1, TYPE_PRECISION (type0)) >= 0 && (complain & tf_warning) && c_inhibit_evaluation_warnings == 0) @@ -5586,6 +5593,37 @@ cp_build_binary_op (const op_location_t &location, shorten == -1); } + /* Shifts can be shortened if shifting right. */ + + if (short_shift) + { + int unsigned_arg; + tree arg0 = get_narrower (op0, &unsigned_arg); + + final_type = result_type; + + if (arg0 == op0 && final_type == TREE_TYPE (op0)) + unsigned_arg = TYPE_UNSIGNED (TREE_TYPE (op0)); + + if (TYPE_PRECISION (TREE_TYPE (arg0)) < TYPE_PRECISION (result_type) + && tree_int_cst_sgn (op1) > 0 + /* We can shorten only if the shift count is less than the + number of bits in the smaller type size. */ + && compare_tree_int (op1, TYPE_PRECISION (TREE_TYPE (arg0))) < 0 + /* We cannot drop an unsigned shift after sign-extension. */ + && (!TYPE_UNSIGNED (final_type) || unsigned_arg)) + { + /* Do an unsigned shift if the operand was zero-extended. */ + result_type + = c_common_signed_or_unsigned_type (unsigned_arg, + TREE_TYPE (arg0)); + /* Convert value-to-be-shifted to that type. */ + if (TREE_TYPE (op0) != result_type) + op0 = convert (result_type, op0); + converted = 1; + } + } + /* Comparison operations are shortened too but differently. They identify themselves by setting short_compare = 1. */ |