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author | Jakub Jelinek <jakub@redhat.com> | 2023-06-16 19:47:28 +0200 |
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committer | Jakub Jelinek <jakub@redhat.com> | 2023-06-16 19:47:28 +0200 |
commit | 2b4e0415ad664cdb3ce87d1f7eee5ca26911a05b (patch) | |
tree | 899721fe206660eca7d72307acf6107606613c05 /libgo | |
parent | 5b67116a85298bbe358b036d34ad23119cebbdac (diff) | |
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uiltins: Add support for clang compatible __builtin_{add,sub}c{,l,ll} [PR79173]
While the design of these builtins in clang is questionable,
rather than being say
unsigned __builtin_addc (unsigned, unsigned, bool, bool *)
so that it is clear they add two [0, 0xffffffff] range numbers
plus one [0, 1] range carry in and give [0, 0xffffffff] range
return plus [0, 1] range carry out, they actually instead
add 3 [0, 0xffffffff] values together but the carry out
isn't then the expected [0, 2] value because
0xffffffffULL + 0xffffffff + 0xffffffff is 0x2fffffffd,
but just [0, 1] whether there was any overflow at all.
It is something used in the wild and shorter to write than the
corresponding
#define __builtin_addc(a,b,carry_in,carry_out) \
({ unsigned _s; \
unsigned _c1 = __builtin_uadd_overflow (a, b, &_s); \
unsigned _c2 = __builtin_uadd_overflow (_s, carry_in, &_s); \
*(carry_out) = (_c1 | _c2); \
_s; })
and so a canned builtin for something people could often use.
It isn't that hard to maintain on the GCC side, as we just lower
it to two .ADD_OVERFLOW calls early, and the already committed
pottern recognization code can then make .UADDC/.USUBC calls out of
that if the carry in is in [0, 1] range and the corresponding
optab is supported by the target.
2023-06-16 Jakub Jelinek <jakub@redhat.com>
PR middle-end/79173
* builtin-types.def (BT_FN_UINT_UINT_UINT_UINT_UINTPTR,
BT_FN_ULONG_ULONG_ULONG_ULONG_ULONGPTR,
BT_FN_ULONGLONG_ULONGLONG_ULONGLONG_ULONGLONG_ULONGLONGPTR): New
types.
* builtins.def (BUILT_IN_ADDC, BUILT_IN_ADDCL, BUILT_IN_ADDCLL,
BUILT_IN_SUBC, BUILT_IN_SUBCL, BUILT_IN_SUBCLL): New builtins.
* builtins.cc (fold_builtin_addc_subc): New function.
(fold_builtin_varargs): Handle BUILT_IN_{ADD,SUB}C{,L,LL}.
* doc/extend.texi (__builtin_addc, __builtin_subc): Document.
* gcc.target/i386/pr79173-11.c: New test.
* gcc.dg/builtin-addc-1.c: New test.
Diffstat (limited to 'libgo')
0 files changed, 0 insertions, 0 deletions