[dev.ssa] cmd/compile/internal/ssa: implement write barriers

For now, we only use typedmemmove.  This can be optimized
in future CLs.

Also add a feature to help with binary searching bad compilations.
Together with GOSSAPKG, GOSSAHASH specifies the last few binary digits
of the hash of function names that should be compiled.  So
GOSSAHASH=0110 means compile only those functions whose last 4 bits
of hash are 0110.  By adding digits to the front we can binary search
for the function whose SSA-generated code is causing a test to fail.

Change-Id: I5a8b6b70c6f034f59e5753965234cd42ea36d524
Reviewed-on: https://go-review.googlesource.com/14530
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/test/nosplit.go b/test/nosplit.go
index e5c2a9f30e..e7c00f5783 100644
--- a/test/nosplit.go
+++ b/test/nosplit.go
@@ -285,12 +285,12 @@ TestCases:
 				// Instead of rewriting the test cases above, adjust
 				// the first stack frame to use up the extra bytes.
 				if i == 0 {
-					size += 512 - 128
+					size += 832 - 128
 					// Noopt builds have a larger stackguard.
 					// See ../cmd/dist/buildruntime.go:stackGuardMultiplier
 					for _, s := range strings.Split(os.Getenv("GO_GCFLAGS"), " ") {
 						if s == "-N" {
-							size += 640
+							size += 960
 						}
 					}
 				}