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| author | Xavier Leroy <xavier.leroy@college-de-france.fr> | 2020-06-25 11:21:31 +0200 |
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| committer | Xavier Leroy <xavierleroy@users.noreply.github.com> | 2020-06-25 16:58:46 +0200 |
| commit | 7fe7aabe4bac5a2250f31045797fce663ec65848 (patch) | |
| tree | 48f2b77bd6f689c1b0be63261c39ce1490982f36 /x86 | |
| parent | c6b86fd5719388301295f9ab4b07b57653e0d8c6 (diff) | |
| download | compcert-kvx-7fe7aabe4bac5a2250f31045797fce663ec65848.tar.gz compcert-kvx-7fe7aabe4bac5a2250f31045797fce663ec65848.zip | |
Eliminate known builtins whose result is ignored
A typical example is `(void) __builtin_sel(a, b, c)`.
It is safe to generate zero code for these uses of builtins
because builtins whose semantics are known to the compiler
are pure. Other builtins with side effects (e.g. `__builtin_trap`)
are not known and will remain in the compiled code.
It is useful to generate zero code for these uses of builtins
because some of them (e.g. `__builtin_sel`) must be transformed
into proper CminorSel expressions during instruction selection.
Otherwise, they propagate all the way to ExpandAsm, causing
a "not implemented" error there.
Diffstat (limited to 'x86')
0 files changed, 0 insertions, 0 deletions