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[Bug inline-asm/10396] Constraint alternatives cause error " `asm' operand requires impossible reload"
- From: "pgonzalez at bluel dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 14 Jan 2004 23:44:47 -0000
- Subject: [Bug inline-asm/10396] Constraint alternatives cause error " `asm' operand requires impossible reload"
- References: <20030414040601.10396.pgonzalez@bluel.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From pgonzalez at bluel dot com 2004-01-14 23:44 -------
(In reply to comment #11)
> Which is only out by a couple of cycles (A couple of redundant mov insns).
> However, by not using an ASM you allow the compiler to schedule the
instructions
> independently, and may also expose additional optimization opportunities.
True, although the purpose of the inline assembly is to recover exactly those
missing cycles. :-) I should note also that the simple example above is
representative of similar problems with more complex cases (e.g. fixed-point
vector multiplication). The workaround we're using right now is a manually-
enabled preprocessor flag that reduces the constraint count in files that
failed to compile without it.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10396