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Use ADD instead of MUL
* On recent CPUs, 2-operand MUL's latency is 3 cycle but ADD is 1 cycle. * clang Optimizes `MUL rax,2` into `ADD rax,rax` but gcc7 doesn't. * LONG2FIX is compiled into `lea r14,[r15+r15*1+0x1]`; this is 1cycle and run in parallel if the branch prediction is correct. * Note that old (RB_POSFIXABLE(f) && RB_NEGFIXABLE(f)) is usually uses following instructions. * movabs rax,0x4000000000000000 * add rax,rdi * js It needs large immediate and Macro-Fusion is not applied. ADD and JO is much smaller though it is also Macro-Fusion unfriendly. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57793 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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2 changed files with 5 additions and 22 deletions
10
bignum.c
10
bignum.c
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@ -4436,18 +4436,8 @@ rb_ull2inum(unsigned LONG_LONG n)
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VALUE
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rb_ll2inum(LONG_LONG n)
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{
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#ifdef HAVE_BUILTIN___BUILTIN_MUL_OVERFLOW
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SIGNED_VALUE v;
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if (__builtin_mul_overflow(n, 2, &v)) {
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return rb_ll2big(n);
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}
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else {
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return ((VALUE)v) | RUBY_FIXNUM_FLAG;
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}
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#else
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if (FIXABLE(n)) return LONG2FIX(n);
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return rb_ll2big(n);
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#endif
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}
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#endif /* HAVE_LONG_LONG */
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@ -359,7 +359,11 @@ rb_fix2ulong(VALUE x)
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#define RB_FIXNUM_P(f) (((int)(SIGNED_VALUE)(f))&RUBY_FIXNUM_FLAG)
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#define RB_POSFIXABLE(f) ((f) < RUBY_FIXNUM_MAX+1)
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#define RB_NEGFIXABLE(f) ((f) >= RUBY_FIXNUM_MIN)
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#define RB_FIXABLE(f) (RB_POSFIXABLE(f) && RB_NEGFIXABLE(f))
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#if defined HAVE_BUILTIN___BUILTIN_ADD_OVERFLOW
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# define RB_FIXABLE(f) ({SIGNED_VALUE a=(f),c; !__builtin_add_overflow(a, a, &c);})
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#else
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# define RB_FIXABLE(f) (RB_POSFIXABLE(f) && RB_NEGFIXABLE(f))
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#endif
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#define FIX2LONG(x) RB_FIX2LONG(x)
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#define FIX2ULONG(x) RB_FIX2ULONG(x)
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#define FIXNUM_P(f) RB_FIXNUM_P(f)
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@ -1507,16 +1511,6 @@ rb_integer_type_p(VALUE obj)
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static inline int
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rb_long2fix_overflow(long l, VALUE *ptr)
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{
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#ifdef HAVE_BUILTIN___BUILTIN_MUL_OVERFLOW
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SIGNED_VALUE v;
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if (__builtin_mul_overflow(l, 2, &v)) {
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return 1;
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}
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else {
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*ptr = ((VALUE)v) | RUBY_FIXNUM_FLAG;
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return 0;
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}
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#else
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if (RB_FIXABLE(l)) {
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*ptr = RB_LONG2FIX(l);
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return 0;
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@ -1524,7 +1518,6 @@ rb_long2fix_overflow(long l, VALUE *ptr)
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else {
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return 1;
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}
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#endif
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}
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#if SIZEOF_INT < SIZEOF_LONG
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