[Bug target/16961] Poor x86-64 performance with 128bit ints

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-07-18 
07:47 -------
The 128 bits arithmetic has improved now: 
 
typedef unsigned long      mp_word __attribute__ ((mode(TI)));  
mp_word a, b;  
void test(void) { a += b; }  
 
test: 
        movq    a(%rip), %rax 
        addq    b(%rip), %rax 
        movq    a+8(%rip), %rdx 
        adcq    b+8(%rip), %rdx 
        movq    %rax, a(%rip) 
        movq    %rdx, a+8(%rip) 
        ret 
 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16961