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From: "marc.glisse at normalesup dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug other/50384] Copying a char array Date: Wed, 14 Sep 2011 08:24:00 -0000 [thread overview] Message-ID: <bug-50384-4-xlF3mb9WuJ@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-50384-4@http.gcc.gnu.org/bugzilla/> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50384 --- Comment #1 from Marc Glisse <marc.glisse at normalesup dot org> 2011-09-14 08:23:15 UTC --- Don't know if it is the same problem, but gcc seems to have trouble optimizing with structs: //typedef struct A { unsigned char t; } A; typedef unsigned char A; extern A f(A,A); A g(A x,A y){ return f(y,x); } Gives a nice: movzbl %dil, %eax movzbl %sil, %edi movl %eax, %esi jmp f whereas if I use the struct definition on the line above: movl %edi, %eax subq $8, %rsp .cfi_def_cfa_offset 16 movl %esi, %edi movl %eax, %esi call f addq $8, %rsp .cfi_def_cfa_offset 8 ret Somehow gcc doesn't realize that the 2 codes are equivalent (at least that's how I understand the ABI).
next prev parent reply other threads:[~2011-09-14 8:23 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-09-13 14:50 [Bug other/50384] New: " marc.glisse at normalesup dot org 2011-09-14 8:24 ` marc.glisse at normalesup dot org [this message] 2012-01-28 20:34 ` [Bug middle-end/50384] Returning std::array is not optimal pinskia at gcc dot gnu.org 2012-01-28 20:57 ` marc.glisse at normalesup dot org 2021-07-21 0:45 ` pinskia at gcc dot gnu.org
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