x/tools/go/ssa: builder crash in map[*S]bool{{}: true}

[alandonovan]

% cat a.go
package p

type S struct{}

var _ = map[*S]bool{{}: true}

% ssadump -build=FSL a.go
build package p
build global initializer [var _ map[*p.S]bool] @ a.go:5:9
build package p end
panic: in p.init: cannot convert *t0 (p.S) to *p.S

goroutine 1 [running]:
golang.org/x/tools/go/ssa.emitConv(0xc8200e6000, 0x7f481dde8920, 0xc8200ce360, 0x7f481dde84a8, 0xc8200be280, 0x0, 0x0)
golang.org/x/tools/go/ssa/emit.go:243 +0xc6d
golang.org/x/tools/go/ssa.(_builder).compLit(0xc8200e3627, 0xc8200e6000, 0x7f481dde8c80, 0xc8200ce2a0, 0xc8200ba280, 0xc8200d0601, 0xc8200e2bf8)
golang.org/x/tools/go/ssa/builder.go:1199 +0x1d96
golang.org/x/tools/go/ssa.(_builder).addr(0xc8200e3627, 0xc8200e6000, 0x7f481dde8270, 0xc8200ba280, 0x78a000, 0x0, 0x0)
golang.org/x/tools/go/ssa/builder.go:361 +0x67f
golang.org/x/tools/go/ssa.(_builder).expr0(0xc8200e3627, 0xc8200e6000, 0x7f481dde8270, 0xc8200ba280, 0x411107, 0x7f481dde8478, 0xc8200c4260, 0x0, 0x0, 0x0, ...)
golang.org/x/tools/go/ssa/builder.go:782 +0x772
golang.org/x/tools/go/ssa.(_builder).expr(0xc8200e3627, 0xc8200e6000, 0x7f481dde8270, 0xc8200ba280, 0x0, 0x0)
golang.org/x/tools/go/ssa/builder.go:531 +0x3b8
golang.org/x/tools/go/ssa.(_builder).assign(0xc8200e3627, 0xc8200e6000, 0x7f481dde8bf0, 0x97d1c8, 0x7f481dde8270, 0xc8200ba280, 0x97d101, 0x0)
golang.org/x/tools/go/ssa/builder.go:503 +0x442
golang.org/x/tools/go/ssa.(_Package).build(0xc8200ce120)
golang.org/x/tools/go/ssa/builder.go:2310 +0x133c
golang.org/x/tools/go/ssa.(_Package).(golang.org/x/tools/go/ssa.build)-fm()
golang.org/x/tools/go/ssa/builder.go:2244 +0x20
sync.(_Once).Do(0xc8200ce14c, 0xc8200e3b38)
/usr/local/google/home/adonovan/go/src/sync/once.go:44 +0xe4
golang.org/x/tools/go/ssa.(*Package).Build(0xc8200ce120)
golang.org/x/tools/go/ssa/builder.go:2244 +0x45
main.doMain(0x0, 0x0)
golang.org/x/tools/cmd/ssadump/main.go:145 +0x965
main.main()
golang.org/x/tools/cmd/ssadump/main.go:71 +0x24

[adonovan]

commit 977844c
Author: Alan Donovan adonovan@google.com
Date: Fri Nov 20 15:08:07 2015 -0500

go/ssa: fix crash when building map[*struct{}]bool{{}: true}

Since Go 1.5, if a key expression in a map literal is itself a composite
literal, the type may be omitted.  An & operation may be implied,
but was not generated, resulting in a type mismatch crash.

Added regression test.
Also, added missing intrinsic math.hasSSE4 to interpreter.

Fixes issue 13341

Change-Id: I6a5e560460cdcac295a500a3fc3738cbe8aa5853
Reviewed-on: https://go-review.googlesource.com/17123
Reviewed-by: Robert Griesemer <gri@golang.org>