The previous expansion used SBCI, which is incorrect because the NEGW
pseudo instruction accepts a DREGS operand (2xGPR8) and SBCI only allows
LD8 registers. One solution could be to correct the NEGW pseudo
instruction, but another solution is to use a different instruction
(sbc) that does accept a GPR8 register and therefore allows more freedom
to the register allocator.
The output now matches avr-gcc for the following code:
int foo(int n) {
return -n;
}
I've found this issue using the machine instruction verifier: it was
complaining about the wrong register class in NEGWRd.mir.
Differential Revision: https://reviews.llvm.org/D97131
Summary: This adds all of the CodeGen tests which currently pass.
Reviewers: arsenm, kparzysz
Subscribers: japaric, wdng
Differential Revision: https://reviews.llvm.org/D26388
llvm-svn: 286418
Ayke van Laethem