From 3f2f21e640682c604d9322ba0708e122d1fcf5ee Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Fri, 17 Sep 2010 20:06:27 +0000
Subject: [PATCH] Attempt to support platforms which don't have fenv.h.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114196 91177308-0d34-0410-b5e6-96231b3b80d8
---
 autoconf/configure.ac              |  1 +
 include/llvm/Config/config.h.cmake |  3 ++
 include/llvm/Config/config.h.in    |  3 ++
 include/llvm/System/FEnv.h         | 50 ++++++++++++++++++++++++++++++
 lib/Analysis/ConstantFolding.cpp   | 19 +++++-------
 5 files changed, 64 insertions(+), 12 deletions(-)
 create mode 100644 include/llvm/System/FEnv.h

diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 7b270c9f4d9..949a74f7112 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1262,6 +1262,7 @@ AC_CHECK_HEADERS([utime.h windows.h])
 AC_CHECK_HEADERS([sys/mman.h sys/param.h sys/resource.h sys/time.h])
 AC_CHECK_HEADERS([sys/types.h sys/ioctl.h malloc/malloc.h mach/mach.h])
 AC_CHECK_HEADERS([valgrind/valgrind.h])
+AC_CHECK_HEADERS([fenv.h])
 if test "$ENABLE_THREADS" -eq 1 ; then
   AC_CHECK_HEADERS(pthread.h,
                    AC_SUBST(HAVE_PTHREAD, 1),
diff --git a/include/llvm/Config/config.h.cmake b/include/llvm/Config/config.h.cmake
index e8feabffdaf..5e0fa1ea9a1 100644
--- a/include/llvm/Config/config.h.cmake
+++ b/include/llvm/Config/config.h.cmake
@@ -461,6 +461,9 @@
 /* Define to 1 if you have the <valgrind/valgrind.h> header file. */
 #cmakedefine HAVE_VALGRIND_VALGRIND_H ${HAVE_VALGRIND_VALGRIND_H}
 
+/* Define to 1 if you have the <fenv.h> header file. */
+#cmakedefine HAVE_FENV_H ${HAVE_FENV_H}
+
 /* Define to 1 if you have the <windows.h> header file. */
 #cmakedefine HAVE_WINDOWS_H ${HAVE_WINDOWS_H}
 
diff --git a/include/llvm/Config/config.h.in b/include/llvm/Config/config.h.in
index d62da1ab037..6fd274d875d 100644
--- a/include/llvm/Config/config.h.in
+++ b/include/llvm/Config/config.h.in
@@ -455,6 +455,9 @@
 /* Define to 1 if you have the <valgrind/valgrind.h> header file. */
 #undef HAVE_VALGRIND_VALGRIND_H
 
+/* Define to 1 if you have the <fenv.h> header file. */
+#undef HAVE_FENV_H
+
 /* Define to 1 if you have the <windows.h> header file. */
 #undef HAVE_WINDOWS_H
 
diff --git a/include/llvm/System/FEnv.h b/include/llvm/System/FEnv.h
new file mode 100644
index 00000000000..4c72eb2ab26
--- /dev/null
+++ b/include/llvm/System/FEnv.h
@@ -0,0 +1,50 @@
+//===- llvm/System/FEnv.h - Host floating-point exceptions ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides an operating system independent interface to
+// floating-point exception interfaces.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SYSTEM_FENV_H
+#define LLVM_SYSTEM_FENV_H
+
+#include "llvm/Config/config.h"
+#include <cerrno>
+#ifdef HAVE_FENV_H
+#include <fenv.h>
+#endif
+
+namespace llvm {
+namespace sys {
+
+/// llvm_fenv_clearexcept - Clear the floating-point exception state.
+static inline void llvm_fenv_clearexcept() {
+#ifdef HAVE_FENV_H
+  feclearexcept(FE_ALL_EXCEPT);
+#endif
+  errno = 0;
+}
+
+/// llvm_fenv_testexcept - Test if a floating-point exception was raised.
+static inline bool llvm_fenv_testexcept() {
+  int errno_val = errno;
+  if (errno_val == ERANGE || errno_val == EDOM)
+    return true;
+#ifdef HAVE_FENV_H
+  if (fetestexcept(FE_ALL_EXCEPT))
+    return true;
+#endif
+  return false;
+}
+
+} // End sys namespace
+} // End llvm namespace
+
+#endif
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 69581ba5ecd..c015231e1ba 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/GetElementPtrTypeIterator.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/System/FEnv.h"
 #include <cerrno>
 #include <cmath>
 #include <fenv.h>
@@ -1040,13 +1041,10 @@ llvm::canConstantFoldCallTo(const Function *F) {
 
 static Constant *ConstantFoldFP(double (*NativeFP)(double), double V, 
                                 const Type *Ty) {
-  feclearexcept(FE_ALL_EXCEPT);
-  errno = 0;
+  sys::llvm_fenv_clearexcept();
   V = NativeFP(V);
-  if (errno != 0 ||
-      fetestexcept(FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)) {
-    feclearexcept(FE_ALL_EXCEPT);
-    errno = 0;
+  if (sys::llvm_fenv_testexcept()) {
+    sys::llvm_fenv_clearexcept();
     return 0;
   }
   
@@ -1060,13 +1058,10 @@ static Constant *ConstantFoldFP(double (*NativeFP)(double), double V,
 
 static Constant *ConstantFoldBinaryFP(double (*NativeFP)(double, double),
                                       double V, double W, const Type *Ty) {
-  feclearexcept(FE_ALL_EXCEPT);
-  errno = 0;
+  sys::llvm_fenv_clearexcept();
   V = NativeFP(V, W);
-  if (errno != 0 ||
-      fetestexcept(FE_DIVBYZERO | FE_UNDERFLOW | FE_OVERFLOW | FE_INVALID)) {
-    feclearexcept(FE_ALL_EXCEPT);
-    errno = 0;
+  if (sys::llvm_fenv_testexcept()) {
+    sys::llvm_fenv_clearexcept();
     return 0;
   }