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From: "yamt at mwd dot biglobe dot ne dot jp" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug optimization/12404] New: pointer to union member problem Date: Thu, 25 Sep 2003 16:56:00 -0000 [thread overview] Message-ID: <20030925155217.12404.yamt@mwd.biglobe.ne.jp> (raw) PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12404 Summary: pointer to union member problem Product: gcc Version: 3.3.1 Status: UNCONFIRMED Severity: normal Priority: P2 Component: optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: yamt at mwd dot biglobe dot ne dot jp CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: i386-unknown-netbsdelf1.6W GCC host triplet: i386--netbsdelf GCC target triplet: i386--netbsdelf compiling the following program with -O2 for i386 yields the latter asm output. % gcc -v Using built-in specs. Configured with: /usr/src/tools/gcc/../../gnu/dist/gcc/configure --enable-long-long --disable-multilib --enable-threads --build=i386-unknown-netbsdelf --host=i386--netbsdelf --target=i386--netbsdelf : (reconfigured) /usr/src/tools/gcc/../../gnu/dist/gcc/configure --enable-long-long --disable-multilib --enable-threads --build=i386-unknown-netbsdelf1.6W --host=i386--netbsdelf --target=i386--netbsdelf Thread model: posix gcc version 3.3.1 ============================================================ #include <stdio.h> int main() { union { int i; short s; } u[] = {{1}, {2}, {3}}; printf("%d\n", *&u->s); } ============================================================ .file "a.c" .section .rodata.str1.1,"aMS",@progbits,1 .LC0: .string "%d\n" .text .p2align 2,,3 .globl main .type main, @function main: pushl %ebp movl %esp, %ebp subl $24, %esp andl $-16, %esp subl $8, %esp movswl -24(%ebp),%eax # <= used before initialized. pushl %eax pushl $.LC0 movl $1, -24(%ebp) # <= initialize here movl $2, -20(%ebp) movl $3, -16(%ebp) call printf leave ret .size main, .-main .ident "GCC: (GNU) 3.3.1"
next reply other threads:[~2003-09-25 15:52 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-09-25 16:56 yamt at mwd dot biglobe dot ne dot jp [this message] 2003-09-25 21:32 ` [Bug optimization/12404] pointer to union member problem (aliasing problem) pinskia at gcc dot gnu dot org 2003-12-25 3:23 ` pinskia at gcc dot gnu dot org
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