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Is there any other optimization for memory?
- From: Parmenides <mobile dot parmenides at gmail dot com>
- To: Gcc mailing list <gcc-help at gcc dot gnu dot org>
- Date: Thu, 14 Jul 2011 04:55:59 +0800
- Subject: Is there any other optimization for memory?
Hi,
Gcc manual describes "memory" clobber in a inline assembly as follows:
If your assembler instructions access memory in an unpredictable
fashion, add `memory' to the list of clobbered registers. This will
cause GCC to not keep memory values cached in registers across the
assembler instruction and not optimize stores or loads to that memory.
I have two questions about it.
1. "This will cause GCC to not keep memory values cached in registers
***across*** the assembler instruction"
What's the exact meaning of "across"? I think that the gcc will reload
a memory value into a register ***after*** the assembler instruction.
Is that the case?
2. "and not optimize stores or loads to that memory"
Except caching memory values in registers, is there any other
optimizaiton for stores or loads to memory?