[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>
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 64391b0..8939f14 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -24,8 +24,32 @@
// it will never return nil, and the bool can be removed.
func buildssa(fn *Node) (ssafn *ssa.Func, usessa bool) {
name := fn.Func.Nname.Sym.Name
+ gossahash := os.Getenv("GOSSAHASH")
usessa = strings.HasSuffix(name, "_ssa") || strings.Contains(name, "_ssa.") || name == os.Getenv("GOSSAFUNC")
+ // Environment variable control of SSA CG
+ // 1. IF GOSSAFUNC == current function name THEN
+ // compile this function with SSA and log output to ssa.html
+
+ // 2. IF GOSSAHASH == "y" or "Y" THEN
+ // compile this function (and everything else) with SSA
+
+ // 3. IF GOSSAHASH == "" THEN
+ // IF GOSSAPKG == current package name THEN
+ // compile this function (and everything in this package) with SSA
+ // ELSE
+ // use the old back end for this function.
+ // This is for compatibility with existing test harness and should go away.
+
+ // 4. IF GOSSAHASH is a suffix of the binary-rendered SHA1 hash of the function name THEN
+ // compile this function with SSA
+ // ELSE
+ // compile this function with the old back end.
+
+ // Plan is for 3 to be remove, and the 2) dependence on GOSSAHASH changes
+ // from "y"/"Y" to empty -- then SSA is default, and is disabled by setting
+ // GOSSAHASH to a value that is neither 0 nor 1 (e.g., "N" or "X")
+
if usessa {
fmt.Println("generating SSA for", name)
dumplist("buildssa-enter", fn.Func.Enter)
@@ -58,17 +82,6 @@
}
}()
- // If SSA support for the function is incomplete,
- // assume that any panics are due to violated
- // invariants. Swallow them silently.
- defer func() {
- if err := recover(); err != nil {
- if !e.unimplemented {
- panic(err)
- }
- }
- }()
-
// We construct SSA using an algorithm similar to
// Brau, Buchwald, Hack, Leißa, Mallon, and Zwinkau
// http://pp.info.uni-karlsruhe.de/uploads/publikationen/braun13cc.pdf
@@ -167,27 +180,17 @@
// Main call to ssa package to compile function
ssa.Compile(s.f)
- // Calculate stats about what percentage of functions SSA handles.
- if false {
- fmt.Printf("SSA implemented: %t\n", !e.unimplemented)
- }
-
- if e.unimplemented {
- return nil, false
- }
-
- // TODO: enable codegen more broadly once the codegen stabilizes
- // and runtime support is in (gc maps, write barriers, etc.)
- if usessa {
+ if usessa || gossahash == "y" || gossahash == "Y" {
return s.f, true
}
- if localpkg.Name != os.Getenv("GOSSAPKG") {
- return s.f, false
- }
- if os.Getenv("GOSSAHASH") == "" {
+ if gossahash == "" {
+ if localpkg.Name != os.Getenv("GOSSAPKG") {
+ return s.f, false
+ }
// Use everything in the package
return s.f, true
}
+
// Check the hash of the name against a partial input hash.
// We use this feature to do a binary search within a package to
// find a function that is incorrectly compiled.
@@ -195,10 +198,26 @@
for _, b := range sha1.Sum([]byte(name)) {
hstr += fmt.Sprintf("%08b", b)
}
- if strings.HasSuffix(hstr, os.Getenv("GOSSAHASH")) {
+
+ if strings.HasSuffix(hstr, gossahash) {
fmt.Printf("GOSSAHASH triggered %s\n", name)
return s.f, true
}
+
+ // Iteratively try additional hashes to allow tests for multi-point
+ // failure.
+ for i := 0; true; i++ {
+ ev := fmt.Sprintf("GOSSAHASH%d", i)
+ evv := os.Getenv(ev)
+ if evv == "" {
+ break
+ }
+ if strings.HasSuffix(hstr, evv) {
+ fmt.Printf("%s triggered %s\n", ev, name)
+ return s.f, true
+ }
+ }
+
return s.f, false
}
@@ -1353,6 +1372,15 @@
// Assume everything will work out, so set up our return value.
// Anything interesting that happens from here is a fatal.
x := s.expr(n.Left)
+
+ // Special case for not confusing GC and liveness.
+ // We don't want pointers accidentally classified
+ // as not-pointers or vice-versa because of copy
+ // elision.
+ if to.IsPtr() != from.IsPtr() {
+ return s.newValue1(ssa.OpConvert, to, x)
+ }
+
v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type
// CONVNOP closure
@@ -1364,6 +1392,7 @@
if from.Etype == to.Etype {
return v
}
+
// unsafe.Pointer <--> *T
if to.Etype == TUNSAFEPTR && from.IsPtr() || from.Etype == TUNSAFEPTR && to.IsPtr() {
return v
