cmd/compile: misuse of REGTMP in optimizer on ppc64 #12597
Description
=== RUN TestTformOver
--- FAIL: TestTformOver (7.61s)
panic: runtime error: index out of range [recovered]
panic: runtime error: index out of range
goroutine 19 [running]:
testing.tRunner.func1(0xc82009c000)
/go/src/testing/testing.go:450 +0x170
vendor/golang.org/x/image/draw.ablInterpolator.transform_RGBA_NRGBA_Over(0xc820016e80, 0xf, 0xa, 0x52, 0x4d, 0x0, 0x0, 0x43, 0x43, 0xc8200a77e0, ...)
/src/golang.org/x/image/draw/impl.go:2998 +0xcf4
Probably a codegen bug.