From 6038e5b155efd6af5740aa6018b04b7ead454176 Mon Sep 17 00:00:00 2001 From: dim Date: Fri, 30 Dec 2011 23:41:24 +0000 Subject: [PATCH] MFC r228536: The TCB_GET32() and TCB_GET64() macros in the i386 and amd64-specific versions of pthread_md.h have a special case of dereferencing a null pointer. Clang warns about this with: In file included from lib/libthr/arch/i386/i386/pthread_md.c:36: lib/libthr/arch/i386/include/pthread_md.h:96:10: error: indirection of non-volatile null pointer will be deleted, not trap [-Werror,-Wnull-dereference] return (TCB_GET32(tcb_self)); ^~~~~~~~~~~~~~~~~~~ lib/libthr/arch/i386/include/pthread_md.h:73:13: note: expanded from: : "m" (*(u_int *)(__tcb_offset(name)))); \ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ lib/libthr/arch/i386/include/pthread_md.h:96:10: note: consider using __builtin_trap() or qualifying pointer with 'volatile' Since this indirection is done relative to the fs or gs segment, to retrieve thread-specific data, it is an exception to the rule. Therefore, add a volatile qualifier to tell the compiler we really want to dereference a zero address. git-svn-id: svn://svn.freebsd.org/base/stable/9@229047 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f --- lib/libthr/arch/amd64/include/pthread_md.h | 2 +- lib/libthr/arch/i386/include/pthread_md.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/lib/libthr/arch/amd64/include/pthread_md.h b/lib/libthr/arch/amd64/include/pthread_md.h index 9f6d3a137..0ebea2e3b 100644 --- a/lib/libthr/arch/amd64/include/pthread_md.h +++ b/lib/libthr/arch/amd64/include/pthread_md.h @@ -71,7 +71,7 @@ struct tcb { u_long __i; \ __asm __volatile("movq %%fs:%1, %0" \ : "=r" (__i) \ - : "m" (*(u_long *)(__tcb_offset(name)))); \ + : "m" (*(volatile u_long *)(__tcb_offset(name)))); \ __result = (__tcb_type(name))__i; \ \ __result; \ diff --git a/lib/libthr/arch/i386/include/pthread_md.h b/lib/libthr/arch/i386/include/pthread_md.h index 5c00cf694..c160aa4fb 100644 --- a/lib/libthr/arch/i386/include/pthread_md.h +++ b/lib/libthr/arch/i386/include/pthread_md.h @@ -70,7 +70,7 @@ struct tcb { u_int __i; \ __asm __volatile("movl %%gs:%1, %0" \ : "=r" (__i) \ - : "m" (*(u_int *)(__tcb_offset(name)))); \ + : "m" (*(volatile u_int *)(__tcb_offset(name)))); \ __result = (__tcb_type(name))__i; \ \ __result; \ -- 2.45.0