f295bde84c
Currently `avo` uses `BP` as a standard general-purpose register. However, `BP` is used for the frame pointer and should be callee-save. Under some circumstances, the Go assembler will do this automatically, but not always. At the moment `avo` can produce code that clobbers the `BP` register. Since Go 1.16 this code will also fail a new `go vet` check. This PR provides a (currently sub-optimal) fix for the issue. It introduces an `EnsureBasePointerCalleeSaved` pass which will check if the base pointer is written to by a function, and if so will artificially ensure that the function has a non-zero frame size. This will trigger the Go assembler to automatically save and restore the BP register. In addition, we update the `asmdecl` tool to `asmvet`, which includes the `framepointer` vet check. Updates #156
Regression test for issue #100 based on the original reported allocation failure.
Based on the pull request
klauspost/compress#186 at
c1f3cf132cd8e214b38cc16e418bf2e501ccda93 with the lines after FIXME
comments re-activated and other minimal edits to make it work in this
environment.
Original code covered by BSD 3-Clause License.