That data is bullshit. It measures -fno-strict-overflow -fno-strict-aliasing. I in fact agree flipping defaults on these UBs is reasonable, but that is very far from "portable assembler" or UB-free C.
THE primary UB of C is out-of-bounds write. Any proposal for UB-free C should address how to compile out-of-bounds write.
If you insist out-of-bounds write should compile in "portable assembler" way and reliably corrupt memory instead of allowing compilers to assume it doesn't happen, compilers can't allocate local variables in register. If it's on stack, out-of-bounds write may reliably corrupt stack, so how can it be on register?
"Portable assembler" people invariably say "that's not what I meant!" when compiler people raise this issue, but the question is "then what do you mean?" And I am yet to see any good answer.
THE primary UB of C is out-of-bounds write. Any proposal for UB-free C should address how to compile out-of-bounds write.
If you insist out-of-bounds write should compile in "portable assembler" way and reliably corrupt memory instead of allowing compilers to assume it doesn't happen, compilers can't allocate local variables in register. If it's on stack, out-of-bounds write may reliably corrupt stack, so how can it be on register?
"Portable assembler" people invariably say "that's not what I meant!" when compiler people raise this issue, but the question is "then what do you mean?" And I am yet to see any good answer.