From 0f59f5c12003e547e7557cc09da39c2abd63403d Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Fri, 16 Jan 2015 23:23:31 +0000
Subject: [PATCH] runtime: Add __sparc__ case for SETCONTEXT_CLOBBERS_TLS.

The glibc setcontext incorrectly modifies %g7 on SPARC.

From Richard Henderson.

From-SVN: r219778
---
 libgo/runtime/proc.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index c4f27fb6bbb..da0f2ed3a75 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -126,6 +126,30 @@ fixcontext(ucontext_t* c)
 	c->uc_mcontext._mc_tlsbase = tlsbase;
 }
 
+# elif defined(__sparc__)
+
+static inline void
+initcontext(void)
+{
+}
+
+static inline void
+fixcontext(ucontext_t *c)
+{
+	/* ??? Using 
+	     register unsigned long thread __asm__("%g7");
+	     c->uc_mcontext.gregs[REG_G7] = thread;
+	   results in
+	     error: variable ‘thread’ might be clobbered by \
+		‘longjmp’ or ‘vfork’ [-Werror=clobbered]
+	   which ought to be false, as %g7 is a fixed register.  */
+
+	if (sizeof (c->uc_mcontext.gregs[REG_G7]) == 8)
+		asm ("stx %%g7, %0" : "=m"(c->uc_mcontext.gregs[REG_G7]));
+	else
+		asm ("st %%g7, %0" : "=m"(c->uc_mcontext.gregs[REG_G7]));
+}
+
 # else
 
 #  error unknown case for SETCONTEXT_CLOBBERS_TLS