cmd/compile: unaligned load constant offsets on ppc64 #44739
Description
package main
type T struct {
x [4]byte
y [8]byte
}
func f(a T, _ byte, b T) bool {
return a.y == b.y
}
% GOOS=linux GOARCH=ppc64le ~/go1.16/bin/go tool compile -S ~/gowork/tmp1.go
compile: invalid offset for DS form load/store 00004 (/Users/khr/gowork/tmp1.go:9) MOVD "".b+17(R1), R4
This has been failing since at least 1.13.
My reading of the PPC64.rules is that 2 byte and 4 byte operations can be at any offset, but 8 byte operations need to be at a multiple of 4. (Search for %4 == 0 in those rules). To be precise, the operations can happen at any address, but we can't encode constant offsets that aren't a multiple of 4. Do I have that correct?
Split off from #42385