From: Matt Birkholz <matt@birkholz.chandler.az.us>
Date: Thu, 2 Jun 2011 05:24:36 +0000 (-0700)
Subject: Implement BORKED_FENV for i386.
X-Git-Tag: 20110609-Gtk~6
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=a10f6e24e9d333d430226b887ae561654a1ac7d6;p=mit-scheme.git

Implement BORKED_FENV for i386.
---

diff --git a/src/microcode/achost.ac b/src/microcode/achost.ac
index e4fc6b517..1bdc2a1f3 100644
--- a/src/microcode/achost.ac
+++ b/src/microcode/achost.ac
@@ -115,6 +115,17 @@ linux-gnu)
     M4_FLAGS="${M4_FLAGS} -P __linux__,1"
     DO_GCC_TESTS=yes
     GNU_LD=yes
+    # In Ubuntu 11.04 on i386 eglibc-2.13's fesetenv(FE_DFL_ENV) does
+    # not mask all FPEs.  Its feclear/disableexcept() functions are
+    # not effective either.  A callout to pango_layout_get_pixel_
+    # extents can use these and still SIGFPE Underflow.  However the
+    # emulation in cmpintmd/x86-fenv.c IS effective.  Defining
+    # BORKED_FENV causes libc's fenv.h to be ignored and x86-fenv.c to
+    # be included.  Not all linux-gnu/i386 hosts need this, but the
+    # emulation should work on all of them.
+    if test "x${mit_scheme_native_code}" = "xi386"; then
+	BORKED_FENV=yes
+    fi
     ;;
 freebsd*)
     M4_FLAGS="${M4_FLAGS} -P SUPPRESS_LEADING_UNDERSCORE,1"
diff --git a/src/microcode/cmpauxmd/x86-64.m4 b/src/microcode/cmpauxmd/x86-64.m4
index 2ae38405c..864f416e1 100644
--- a/src/microcode/cmpauxmd/x86-64.m4
+++ b/src/microcode/cmpauxmd/x86-64.m4
@@ -990,22 +990,22 @@ define_c_label(x87_trap_exceptions)
 
 define_c_label(x87_read_control_word)
 	enter		IMM(4),IMM(0)
-	fnstcw		IND(REG(esp))
-	OP(mov,w)	TW(IND(REG(esp)),REG(ax))
+	fnstcw		IND(REG(rsp))
+	OP(mov,w)	TW(IND(REG(rsp)),REG(ax))
 	leave
 	ret
 
 define_c_label(x87_write_control_word)
 	enter		IMM(4),IMM(0)
 	OP(mov,w)	TW(REG(di),IND(REG(rsp)))
-	fldcw		IND(REG(esp))
+	fldcw		IND(REG(rsp))
 	leave
 	ret
 
 define_c_label(x87_read_status_word)
 	enter		IMM(4),IMM(0)
-	fnstsw		IND(REG(esp))
-	OP(mov,w)	TW(IND(REG(esp)),REG(ax))
+	fnstsw		IND(REG(rsp))
+	OP(mov,w)	TW(IND(REG(rsp)),REG(ax))
 	leave
 	ret
 
@@ -1013,7 +1013,7 @@ define_c_label(x87_read_environment)
 	fnstenv		IND(REG(rdi))
 	# fnstenv masks all exceptions (go figure), so we must load
 	# the control word back in order to undo that.
-	fldcw		IND(REG(eax))
+	fldcw		IND(REG(rdi))
 	ret
 
 define_c_label(x87_write_environment)
diff --git a/src/microcode/cmpintmd/i386.c b/src/microcode/cmpintmd/i386.c
index 0d66de11b..152e93e63 100644
--- a/src/microcode/cmpintmd/i386.c
+++ b/src/microcode/cmpintmd/i386.c
@@ -391,7 +391,7 @@ i386_reset_hook (void)
 #endif /* _MACH_UNIX */
 }
 
-#ifndef HAVE_FENV_H
+#if !defined(HAVE_FENV_H) || defined(BORKED_FENV)
 extern int i387_presence;
 extern int sse_presence;
 #  define x87_p i387_presence
diff --git a/src/microcode/cmpintmd/i386.h b/src/microcode/cmpintmd/i386.h
index f07d5c240..db76f50ab 100644
--- a/src/microcode/cmpintmd/i386.h
+++ b/src/microcode/cmpintmd/i386.h
@@ -335,7 +335,7 @@ extern void i386_reset_hook (void);
 
 extern int ia32_cpuid_needed;
 
-#ifndef HAVE_FENV_H
+#if !defined(HAVE_FENV_H) || defined(BORKED_FENV)
 #  define CMPINTMD_EMULATES_FENV
 #  include "cmpintmd/x86-fenv.h"
 #endif
diff --git a/src/microcode/cmpintmd/x86-fenv.h b/src/microcode/cmpintmd/x86-fenv.h
index dc5ddcd2e..a65f40ee7 100644
--- a/src/microcode/cmpintmd/x86-fenv.h
+++ b/src/microcode/cmpintmd/x86-fenv.h
@@ -26,6 +26,23 @@ USA.
 
 /* C99 <fenv.h> emulation for x86 (shared between i386 and amd64) */
 
+#ifdef BORKED_FENV
+# undef HAVE_FEGETROUND
+# undef HAVE_FESETROUND
+# undef HAVE_FECLEAREXCEPT
+# undef HAVE_FEGETEXCEPTFLAG
+# undef HAVE_FERAISEEXCEPT
+# undef HAVE_FESETEXCEPTFLAG
+# undef HAVE_FETESTEXCEPT
+# undef HAVE_FEDISABLEEXCEPT
+# undef HAVE_FEENABLEEXCEPT
+# undef HAVE_FEGETEXCEPT
+# undef HAVE_FEGETENV
+# undef HAVE_FESETENV
+# undef HAVE_FEHOLDEXCEPT
+# undef HAVE_FEUPDATEENV
+#endif
+
 #define HAVE_FENV_T
 #define HAVE_FEXCEPT_T
 
diff --git a/src/microcode/configure.ac b/src/microcode/configure.ac
index 642cf04a0..0a9b68845 100644
--- a/src/microcode/configure.ac
+++ b/src/microcode/configure.ac
@@ -369,8 +369,13 @@ define([SCM_INC_FENV],
     ])
 
 if test "x$ac_cv_header_fenv_h" = "xyes"; then
-  AC_CHECK_TYPES([fenv_t], [], [], [SCM_INC_FENV])
-  AC_CHECK_TYPES([fexcept_t], [], [], [SCM_INC_FENV])
+  if test "x$BORKED_FENV" = "xyes"; then
+    AC_DEFINE([BORKED_FENV], [1],
+	[Define to 1 if your fenv implementation is broken.])
+  else
+    AC_CHECK_TYPES([fenv_t], [], [], [SCM_INC_FENV])
+    AC_CHECK_TYPES([fexcept_t], [], [], [SCM_INC_FENV])
+  fi
 fi
 
 AC_CHECK_SIZEOF([time_t])
diff --git a/src/microcode/floenv.h b/src/microcode/floenv.h
index 6ab58ac79..0ff82ae40 100644
--- a/src/microcode/floenv.h
+++ b/src/microcode/floenv.h
@@ -32,7 +32,7 @@ USA.
 
 #include "cmpintmd.h"
 
-#if (defined (HAVE_FENV_H))
+#if (defined (HAVE_FENV_H) && !defined (BORKED_FENV))
 #  include <fenv.h>
 #  ifdef HAVE_FENV_T
 #    define scheme_fenv_t fenv_t