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From: Dimitry Andric <dim@FreeBSD.org>
Date: Fri, 7 Aug 2015 20:13:04 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject: svn commit: r286421 - projects/clang-trunk/lib/msun/src
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Author: dim
Date: Fri Aug  7 20:13:04 2015
New Revision: 286421
URL: https://svnweb.freebsd.org/changeset/base/286421

Log:
  Apply an atrocious hack to libm's pow() implementation, to work around
  LLVM PR 24343.  This fixes the graphics/png build on i386, which
  otherwise failed during its tests because of floating point exceptions,
  leading to >5000 skipped other ports.

Modified:
  projects/clang-trunk/lib/msun/src/e_pow.c

Modified: projects/clang-trunk/lib/msun/src/e_pow.c
==============================================================================
--- projects/clang-trunk/lib/msun/src/e_pow.c	Fri Aug  7 19:56:22 2015	(r286420)
+++ projects/clang-trunk/lib/msun/src/e_pow.c	Fri Aug  7 20:13:04 2015	(r286421)
@@ -162,7 +162,13 @@ __ieee754_pow(double x, double y)
 	if(lx==0) {
 	    if(ix==0x7ff00000||ix==0||ix==0x3ff00000){
 		z = ax;			/*x is +-0,+-inf,+-1*/
-		if(hy<0) z = one/z;	/* z = (1/|x|) */
+		if(hy<0) {
+#ifdef __i386__
+		    /* XXX: Work around llvm PR 24343: */
+		    __compiler_membar();
+#endif
+		    z = one/z;	/* z = (1/|x|) */
+		}
 		if(hx<0) {
 		    if(((ix-0x3ff00000)|yisint)==0) {
 			z = (z-z)/(z-z); /* (-1)**non-int is NaN */