| Summary: | incorrect code on -O2 without -fno-tree-pre | ||
|---|---|---|---|
| Product: | gcc | Reporter: | zephyrtronium |
| Component: | tree-optimization | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | normal | ||
| Priority: | P3 | ||
| Version: | 4.5.2 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | ||
| Attachments: | minimal case | ||
You are violating c/c++ aliasing rules. The code is undefined. Sent from my Palm Pre on AT&T On Feb 11, 2011 22:27, zephyrtronium at gmail dot com <gcc-bugzilla@gcc.gnu.org> wrote: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47708 Summary: incorrect code on -O2 without -fno-tree-pre Product: gcc Version: 4.5.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned@gcc.gnu.org ReportedBy: zephyrtronium@gmail.com Created attachment 23310 [details] --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23310 minimal case gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.5.2/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc-4.5.2/configure --enable-lto Thread model: posix gcc version 4.5.2 (GCC) Compiling the following minimal case on -O2 or -O3 and running results in incorrect output; with -O0, -O1, or -Os, it is correct. -O2 -fno-tree-pre results in correct output, but -O1 -ftree-pre is also correct. GCC 4.4.3 appears to work. |
Created attachment 23310 [details] minimal case gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-unknown-linux-gnu/4.5.2/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc-4.5.2/configure --enable-lto Thread model: posix gcc version 4.5.2 (GCC) Compiling the following minimal case on -O2 or -O3 and running results in incorrect output; with -O0, -O1, or -Os, it is correct. -O2 -fno-tree-pre results in correct output, but -O1 -ftree-pre is also correct. GCC 4.4.3 appears to work.