cmd/compile: f.NamedValue entry for reg param causes register allocator miscompile #46304
Description
What version of Go are you using (go version)?
$ go version go version devel go1.17-831573cd21 Fri May 21 03:21:56 2021 +0000 linux/amd64
Does this issue reproduce with the latest release?
This is a problem on tip, not in previous releases.
What operating system and processor architecture are you using (go env)?
linux/amd64
What did you do?
Run this program:
https://play.golang.org/p/spT4IJFC6_n
What did you expect to see?
Program should print "anew" and terminate.
What did you see instead?
panic: runtime error: index out of range [0] with length 0
goroutine 1 [running]:
main.(*M).walkOp(0xc0000f0e08, 0xc0000f4000)
/tmp/repro.go:50 +0x29c
main.main()
/tmp/repro.go:63 +0x145
exit status 2
Bisection identifies this commit as the problem:
https://go.googlesource.com/go/+/f62739b8611a0f1c96e59eb6574422562bb46233
which corresponds to the CL https://go-review.googlesource.com/c/go/+/316890.