math: adjust compilation flags, use them when testing

    
    We were using special compilation flags for the math package, but we
    weren't using them when testing.  That meant that our tests were not
    checking the real code we were providing.  Fix that.
    
    Fixing that revealed that we were not using a good set of flags, or at
    least were not using flags that let the tests pass.  Adjust the flags
    to stop using -funsafe-math-optimizations on x86.  Instead always use
    -ffp-contract=off -fno-math-errno -fno-trapping-math for all targets.
    
    Fixes golang/go#23647
    
    Reviewed-on: https://go-review.googlesource.com/91355

From-SVN: r257312

5 files changed, 12 insertions, 13 deletions

diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index 88be5db..531f8f0 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -1138,6 +1138,7 @@ $(foreach package,$(GOTOOL_PACKAGES),$(eval $(call PACKAGE_template,$(package)))
 # Pass -ffp-contract=off, or 386-specific options, when building the
 # math package.  MATH_FLAG is defined in configure.ac.
 math_lo_GOCFLAGS = $(MATH_FLAG)
+math_check_GOCFLAGS = $(MATH_FLAG)
 
 # Add the generated file runtime_sysinfo.go to the runtime package.
 extra_go_files_runtime = runtime_sysinfo.go sigtab.go
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 471a047..fbca83e 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -1175,6 +1175,7 @@ CHECK_DEPS = $(toolexeclibgo_DATA) $(toolexeclibgoarchive_DATA) \
 # Pass -ffp-contract=off, or 386-specific options, when building the
 # math package.  MATH_FLAG is defined in configure.ac.
 math_lo_GOCFLAGS = $(MATH_FLAG)
+math_check_GOCFLAGS = $(MATH_FLAG)
 
 # Add the generated file runtime_sysinfo.go to the runtime package.
 extra_go_files_runtime = runtime_sysinfo.go sigtab.go
diff --git a/libgo/configure b/libgo/configure
index d0550c3..aba4dc3 100755
--- a/libgo/configure
+++ b/libgo/configure
@@ -15076,10 +15076,9 @@ fi
 $as_echo "$libgo_cv_c_fancymath" >&6; }
 MATH_FLAG=
 if test "$libgo_cv_c_fancymath" = yes; then
-  MATH_FLAG="-mfancy-math-387 -funsafe-math-optimizations -fno-math-errno"
-else
-  MATH_FLAG="-ffp-contract=off"
+  MATH_FLAG="-mfancy-math-387"
 fi
+MATH_FLAG="${MATH_FLAG} -ffp-contract=off -fno-math-errno -fno-trapping-math"
 
 
 CFLAGS_hold=$CFLAGS
diff --git a/libgo/configure.ac b/libgo/configure.ac
index c497e78..1264a1d 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -649,8 +649,7 @@ fi
 AC_SUBST(STRINGOPS_FLAG)
 
 dnl For x86 we want to compile the math library with -mfancy-math-387
-dnl -funsafe-math-optimizations so that we can use the builtin
-dnl instructions directly.
+dnl so that we can use the builtin instructions directly.
 AC_CACHE_CHECK([whether compiler supports -mfancy-math-387],
 [libgo_cv_c_fancymath],
 [CFLAGS_hold=$CFLAGS
@@ -661,10 +660,9 @@ AC_COMPILE_IFELSE([int i;],
 CFLAGS=$CFLAGS_hold])
 MATH_FLAG=
 if test "$libgo_cv_c_fancymath" = yes; then
-  MATH_FLAG="-mfancy-math-387 -funsafe-math-optimizations -fno-math-errno"
-else
-  MATH_FLAG="-ffp-contract=off"
+  MATH_FLAG="-mfancy-math-387"
 fi
+MATH_FLAG="${MATH_FLAG} -ffp-contract=off -fno-math-errno -fno-trapping-math"
 AC_SUBST(MATH_FLAG)
 
 CFLAGS_hold=$CFLAGS
diff --git a/libgo/go/math/all_test.go b/libgo/go/math/all_test.go
index 6682395..98437b0 100644
--- a/libgo/go/math/all_test.go
+++ b/libgo/go/math/all_test.go
@@ -128,7 +128,7 @@ var cbrt = []float64{
 var ceil = []float64{
 	5.0000000000000000e+00,
 	8.0000000000000000e+00,
-	0.0000000000000000e+00,
+	Copysign(0, -1),
 	-5.0000000000000000e+00,
 	1.0000000000000000e+01,
 	3.0000000000000000e+00,
@@ -644,7 +644,7 @@ var tanh = []float64{
 var trunc = []float64{
 	4.0000000000000000e+00,
 	7.0000000000000000e+00,
-	-0.0000000000000000e+00,
+	Copysign(0, -1),
 	-5.0000000000000000e+00,
 	9.0000000000000000e+00,
 	2.0000000000000000e+00,
@@ -2134,7 +2134,7 @@ func TestCbrt(t *testing.T) {
 
 func TestCeil(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
-		if f := Ceil(vf[i]); ceil[i] != f {
+		if f := Ceil(vf[i]); !alike(ceil[i], f) {
 			t.Errorf("Ceil(%g) = %g, want %g", vf[i], f, ceil[i])
 		}
 	}
@@ -2361,7 +2361,7 @@ func TestDim(t *testing.T) {
 
 func TestFloor(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
-		if f := Floor(vf[i]); floor[i] != f {
+		if f := Floor(vf[i]); !alike(floor[i], f) {
 			t.Errorf("Floor(%g) = %g, want %g", vf[i], f, floor[i])
 		}
 	}
@@ -2884,7 +2884,7 @@ func TestTanh(t *testing.T) {
 
 func TestTrunc(t *testing.T) {
 	for i := 0; i < len(vf); i++ {
-		if f := Trunc(vf[i]); trunc[i] != f {
+		if f := Trunc(vf[i]); !alike(trunc[i], f) {
 			t.Errorf("Trunc(%g) = %g, want %g", vf[i], f, trunc[i])
 		}
 	}