Parmenides <mobile.parmenides@xxxxxxxxx> writes: > 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? That is the case. Perhaps this is a language issue as I think the English is clear. GCC will not keep a memory value cached in a register from before to asm instruction to after the asm instruction--or, in other words, across the instruction. > 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? Not in this case, I think it's just another way of saying the same thing. Ian
