> Yes, it is a complete solution. Tracking register liveness is > different issue, and a register is indeed dead after instruction, if > it has been clobbered by insn, or when marked unused.
My concern was liveness within the new sequence of instructions: suppose you have (set (reg:M x) (...)) REG_UNUSED (reg:M x) and we "peephole" the instruction. Is the live range of (reg:M x) properly extended within the new sequence of instructions? > The problem my patch solves is the answer to the question "Is the > choosen non-live temporary register untouched over the insn > sequence?". The answer: "Yes, if it was not set or clobbered by any > insn in the sequence". Are you sure that you don't need to do this in addition to the existing test, instead of in lieu of the existing test? -- Eric Botcazou
