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From: Zoltan Hidvegi <hzoli@austin.ibm.com> To: gcc-gnats@gcc.gnu.org Subject: optimization/3384: PowerPC -funroll-loops -fbranch-count-reg misoptimization Date: Fri, 22 Jun 2001 16:36:00 -0000 [thread overview] Message-ID: <200106222331.SAA28662@vlad.austin.ibm.com> (raw) >Number: 3384 >Category: optimization >Synopsis: PowerPC -funroll-loops -fbranch-count-reg misoptimization >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: wrong-code >Submitter-Id: net >Arrival-Date: Fri Jun 22 16:36:01 PDT 2001 >Closed-Date: >Last-Modified: >Originator: Zoltan Hidvegi >Release: 3.0 >Organization: >Environment: System: AIX vlad 3 4 0005BA2F4C00 host: powerpc-ibm-aix4.3.3.0 build: powerpc-ibm-aix4.3.3.0 target: powerpc-ibm-aix4.3.3.0 configured with: ../gcc-3.0/configure --enable-languages=c,c++,java --enable-version-specific-runtime-libs --disable-nls >Description: gcc-3.0 miscompiles code with -O2 -funroll-loops Workaround: use -fno-branch-count-reg or do not use -funroll-loops This is a regression to 2.95.3 but only if you use -funroll-loops. The testcase: ------------ BEGIN --------------- typedef unsigned long ulong; void set_offsets(ulong *t, ulong idx, ulong n, ulong v) { ulong i; for (i = idx; i < n; i += 2) { t[i] = v; } } int main(void) { ulong a[8]; set_offsets(a, 0, 7, 0xdeafcabe); return 1; } ------------- END ---------------- >How-To-Repeat: % gcc -O2 -funroll-loops -o bug bug.c % ./bug zsh: 16798 segmentation fault ./bug >Fix: Use -fno-branch-count-reg or do not use -funroll-loops >Release-Note: >Audit-Trail: >Unformatted:
next reply other threads:[~2001-06-22 16:36 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2001-06-22 16:36 Zoltan Hidvegi [this message] 2001-07-20 10:39 dje 2001-07-20 20:25 dje 2002-04-02 14:32 dje
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