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[Bug target/16961] Poor x86-64 performance with 128bit ints
- From: "steven at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 18 Jul 2005 07:47:16 -0000
- Subject: [Bug target/16961] Poor x86-64 performance with 128bit ints
- References: <20040810130811.16961.tomstdenis@iahu.ca>
- Reply-to: gcc-bugzilla 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
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16961