Messages in this thread | | | Date | Thu, 16 Nov 2017 11:01:44 -0600 | From | Segher Boessenkool <> | Subject | Re: [PATCH v2 11/18] arm64: make mrs_s and msr_s macros work with LTO |
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On Thu, Nov 16, 2017 at 08:46:08AM -0800, Sami Tolvanen wrote: > On Thu, Nov 16, 2017 at 07:56:50AM -0600, Segher Boessenkool wrote: > > The compiler is fine, the assembler is fine (and the linker has > > nothing to do with it). Your code is not fine. > > Would you care to elaborate? The current code assumes that macros are > visible in other inline assembly blocks, and LLVM developers seem to > feel this isn't correct behavior. This patch fixes the current code so > it works with both assemblers.
If you say e.g.
void f(void) { asm(".macro something\n\t.endm"); }
there is nothing that prevents the compiler from emitting this more than once. Expecting things to be emitted in whatever order is a bad idea, too.
The thing with .purgem can work. Inelegant, sure, but it can work :-) Just make sure you do the macro define, the code that uses it, and the undefine, all in the same inline asm statement.
Segher
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