runtime: ignore exceptions from foreign threads.
Fixes #8224.
LGTM=alex.brainman, rsc
R=alex.brainman, rsc, dave
CC=golang-codereviews
https://golang.org/cl/104200046
diff --git a/src/pkg/runtime/sys_windows_amd64.s b/src/pkg/runtime/sys_windows_amd64.s
index c3db2c1..72b905e 100644
--- a/src/pkg/runtime/sys_windows_amd64.s
+++ b/src/pkg/runtime/sys_windows_amd64.s
@@ -120,6 +120,10 @@
// fetch g
get_tls(DX)
+ CMPQ DX, $0
+ JNE 3(PC)
+ MOVQ $0, AX // continue
+ JMP done
MOVQ g(DX), DX
CMPQ DX, $0
JNE 2(PC)
@@ -131,6 +135,7 @@
CALL runtime·sighandler(SB)
// AX is set to report result back to Windows
+done:
// restore registers as required for windows callback
MOVQ 24(SP), R15
MOVQ 32(SP), R14
