[pcwalton]

That would be a terrible idea. LLVM IR has an inefficient in-memory representation; every IR node is separately heap-allocated via new and chained together via pointers. This is probably a suboptimal design for the compiler, but it would go from suboptimal to disastrous if directly used for execution.

[oconnor0]

I don't think an implementation of LLVM IR for execution would require the same in-memory representation.

[makapuf]

Exactly, my point was more that as we're having C-optimized processors and microcontrollers or even java or lisp based ones, maybe once there is many software readily compileable with llvm maybe architectures could be optimized for it (but not directly porting it, just having a tiny final step llvm based microcode. By example of course you can't have infinite registers as ssa. But it ca' influence your instruction set.

[pcwalton]

That's not the only reason why you wouldn't want to run LLVM IR directly (if it were possible). You still have the types, which are useless at runtime, and the unlimited register file to deal with.

You could make an ISA which is similar to LLVM IR, but there'd be little point when RISC-V (or even AArch64) already exists.