joerg added a comment.
The other problem is that we don't use the CFG machinery to prune dead
branches. Consider the x86 in/out instructions: one variant takes an immediate,
the other a register. The classic way to deal with that is something like
static inline void outl(unsigned port, uint32_t value)
{
if (__builtin_constant_p(port) && port < 0x100) {
__asm volatile("outl %0,%w1" : : "a" (data), "id" (port));
} else {
__asm volatile("outl %0,%w1" : : "a" (data), "d" (port));
}
}
This fails with the new asm constraint checks, since the dead branch is never
pruned. For other architectures it makes an even greater difference. The main
reason it is a show stopper: there is no sane workaround that doesn't regress
code quality.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D58821/new/
https://reviews.llvm.org/D58821
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
