From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Fri, 9 Sep 2016 16:39:44 +0000 (+0000)
Subject: runtime: use alignof to check alignment of ucontext_t
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ac376b15df246bc673b0e14074a4f19d39762480;p=gcc.git

runtime: use alignof to check alignment of ucontext_t

    Use alignof rather than assuming a 16 byte alignment.

    Reviewed-on: https://go-review.googlesource.com/28913

From-SVN: r240047
---

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 99e32cec32d..261a79ae2bb 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-b37a9e66ea584885043240f8f6f1d1c0284eadec
+6c1f159cdcb56ebff617f6bbc6c97943a1a8a34d
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index 7e2b172492e..6ac8857338b 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -166,7 +166,13 @@ static ucontext_t*
 ucontext_arg(void** go_ucontext)
 {
 	uintptr_t p = (uintptr_t)go_ucontext;
-	p = (p + 15) &~ (uintptr_t)0xf;
+	size_t align = __alignof__(ucontext_t);
+	if(align > 16) {
+		// We only ensured space for up to a 16 byte alignment
+		// in libgo/go/runtime/runtime2.go.
+		runtime_throw("required alignment of ucontext_t too large");
+	}
+	p = (p + align - 1) &~ (uintptr_t)(align - 1);
 	return (ucontext_t*)p;
 }