[dev.ssa] cmd/compile: enhance SSA filtering, add OpConvert

Modified GOSSA{HASH.PKG} environment variable filters to
make it easier to make/run with all SSA for testing.
Disable attempts at SSA for architectures that are not
amd64 (avoid spurious errors/unimplementeds.)

Removed easy out for unimplemented features.

Add convert op for proper liveness in presence of uintptr
to/from unsafe.Pointer conversions.

Tweaked stack sizes to get a pass on windows;
1024 instead 768, was observed to pass at least once.

Change-Id: Ida3800afcda67d529e3b1cf48ca4a3f0fa48b2c5
Reviewed-on: https://go-review.googlesource.com/16201
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/ssa/tighten.go b/src/cmd/compile/internal/ssa/tighten.go
index 1da5071a2a..4fa26d2d18 100644
--- a/src/cmd/compile/internal/ssa/tighten.go
+++ b/src/cmd/compile/internal/ssa/tighten.go
@@ -54,8 +54,12 @@ func tighten(f *Func) {
 		for _, b := range f.Blocks {
 			for i := 0; i < len(b.Values); i++ {
 				v := b.Values[i]
-				if v.Op == OpPhi || v.Op == OpGetClosurePtr {
-					// GetClosurePtr must stay in entry block
+				if v.Op == OpPhi || v.Op == OpGetClosurePtr || v.Op == OpConvert {
+					// GetClosurePtr must stay in entry block.
+					// OpConvert must not float over call sites.
+					// TODO do we instead need a dependence edge of some sort for OpConvert?
+					// Would memory do the trick, or do we need something else that relates
+					// to safe point operations?
 					continue
 				}
 				if len(v.Args) > 0 && v.Args[len(v.Args)-1].Type.IsMemory() {