Hi! On Sat, Dec 29, 2018 at 10:41:54AM +0300, Alexander Monakov wrote: > On Sat, 29 Dec 2018, Bin.Cheng wrote: > > tracer-1.c: Assembler messages: > > tracer-1.c:16: Error: symbol `foo_label' is already defined > > > > Root cause is in tracer.c which duplicates basic block without > > checking if any GIMPLE_ASM defines labels. > > Is this a bug or invalid code? > > This is invalid code, GCC documentation is clear that the compiler > may duplicate inline asm statements (passes other than tracer can do > that too, loop unswitching just to give one example). > > We don't provide a way to write an asm that wouldn't be duplicated.
But should there be? Is there (valid!) code for which it would be more convenient? We already have a hook targetm.cannot_copy_insn_p with which targets can say not to copy certain insns. It will be trivial to do something like that for "asm restrict" (or whatever is a better name :-) ) (so make some cannot_copy_insn_p that for asm checks that flag, and for everything else uses the hook... something like that). Segher
