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From: mark@cal005304.student.utwente.nl To: gcc-gnats@gcc.gnu.org Subject: optimization/8832: "asm volatile" code is removed Date: Thu, 05 Dec 2002 14:46:00 -0000 [thread overview] Message-ID: <20021205224223.25925.qmail@sources.redhat.com> (raw) >Number: 8832 >Category: optimization >Synopsis: "asm volatile" code is removed >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: wrong-code >Submitter-Id: net >Arrival-Date: Thu Dec 05 14:46:02 PST 2002 >Closed-Date: >Last-Modified: >Originator: mark >Release: 3.2 and beyond (2.95.3 was still ok) >Organization: >Environment: >Description: I have the following test program: void t(int v) { asm volatile ("movaps %xmm0,%xmm1"); if(v&7) asm volatile ("movaps %xmm1,%xmm2"); asm volatile ("movaps %xmm2,%xmm1"); if(v&7) asm volatile ("movaps %xmm3,%xmm2"); asm volatile ("movaps %xmm4,%xmm1"); } With gcc-3.2/3.2.1/3.3 (Invoked with: gcc -O3 -c bug.cpp) produces the following code: 0: 55 push %ebp 1: 89 e5 mov %esp,%ebp 3: 0f 28 c8 movaps %xmm0,%xmm1 6: f6 45 08 07 testb $0x7,0x8(%ebp) a: 74 09 je 15 <_Z2tti+0x15> c: 0f 28 d1 movaps %xmm1,%xmm2 f: 0f 28 ca movaps %xmm2,%xmm1 12: 0f 28 d3 movaps %xmm3,%xmm2 15: 0f 28 cc movaps %xmm4,%xmm1 18: 5d pop %ebp 19: c3 ret This is not what I want because "movaps %xmm1,%xmm2" is not done if v==7. Is this a bug, or am I doing something wrong ? The code used to work correctly, gcc 2.95.3 (same system and options) produces the code below, which does excactly what I expect it to do: 0: 55 push %ebp 1: 89 e5 mov %esp,%ebp 3: 0f 28 c8 movaps %xmm0,%xmm1 6: 8b 45 08 mov 0x8(%ebp),%eax 9: 83 e0 07 and $0x7,%eax c: 74 03 je 11 <tt__Fi+0x11> e: 0f 28 d1 movaps %xmm1,%xmm2 11: 0f 28 ca movaps %xmm2,%xmm1 14: 85 c0 test %eax,%eax 16: 74 03 je 1b <tt__Fi+0x1b> 18: 0f 28 d3 movaps %xmm3,%xmm2 1b: 0f 28 cc movaps %xmm4,%xmm1 1e: c9 leave 1f: c3 ret >How-To-Repeat: >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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