tree aa8ca2a25413df5fc40421e8eafa3df6951da545
parent 82a761b656704c07a94c12b10141a0cdba1a4534
author Josh Bleecher Snyder <josharian@gmail.com> 1423179533 -0800
committer Josh Bleecher Snyder <josharian@gmail.com> 1423249547 +0000

cmd/gc: eliminate dead code in switch statements

Ordinary switch statements are rewritten
into a sequence of if statements.
Staticly dead cases were not being eliminated
because the rewrite introduced a temporary,
which hid the fact that the case was a constant.
Stop doing that.

This eliminates dead code in the standard library at:

runtime/cgocall.go:219
runtime/cgocall.go:269
debug/gosym/pclntab.go:175
debug/macho/file.go:208
math/big/nat.go:635
math/big/nat.go:850
math/big/nat.go:1058
cmd/pprof/internal/commands/commands.go:86
net/sock_bsd.go:19
cmd/go/build.go:2657
cmd/go/env.go:90

Fixes #9608.

Change-Id: Ic23a05dfbb1ad91d5f62a6506b35a13e51b33e38
Reviewed-on: https://go-review.googlesource.com/3980
Reviewed-by: Keith Randall <khr@golang.org>