Hello!
According to C99, reminder function returns:
If x or y is a NaN, a NaN is returned.
If x is an infinity, and y is not a NaN, a domain error occurs,
and a NaN is returned.
If y is zero, and x is not a NaN, a domain error occurs, and a
NaN is returned.
and fmod returns:
If x or y is a NaN, a NaN is returned.
If x is an infinity, a domain error occurs, and a NaN is returned.
If y is zero, a domain error occurs, and a NaN is returned.
If x is +0 (-0), and y is not zero, +0 (-0) is returned.
However, x87 fprem and fprem1 instructions that are used to implement
these builtin functions do not return NaN for infinities, but generate
invalid-arithmetic-operand exception.
Attached patch enables these builtins for finite math only, consistent
with gcc documentation:
'-ffinite-math-only':
Allow optimizations for floating-point arithmetic that assume that
arguments and results are not NaNs or +-Infs.
This option is not turned on by any '-O' option since it can result
in incorrect output for programs that depend on an exact
implementation of IEEE or ISO rules/specifications for math
functions. It may, however, yield faster code for programs that do
not require the guarantees of these specifications.
2014-09-30 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.md (fmodxf3): Enable for flag_finite_math_only only.
(fmod<mode>3): Ditto.
(fpremxf4_i387): Ditto.
(reminderxf3): Ditto.
(reminder<mode>3): Ditto.
(fprem1xf4_i387): Ditto.
Patch was bootstrapped and regression tested on x86_64-linux-gnu
{,-m32}. The patch also fixes ieee_2.f90 testsuite failure with FX's
pending IEEE support improvement patch.
2014-09-30 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.md (fmodxf3): Enable for flag_finite_math_only only.
(fmod<mode>3): Ditto.
(fpremxf4_i387): Ditto.
(reminderxf3): Ditto.
(reminder<mode>3): Ditto.
(fprem1xf4_i387): Ditto.
The patch will be committed to mainline and other release branches.
Uros.
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 215705)
+++ config/i386/i386.md (working copy)
@@ -13813,7 +13813,8 @@
(set (reg:CCFP FPSR_REG)
(unspec:CCFP [(match_dup 2) (match_dup 3)]
UNSPEC_C2_FLAG))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
"fprem"
[(set_attr "type" "fpspc")
(set_attr "mode" "XF")])
@@ -13822,7 +13823,8 @@
[(use (match_operand:XF 0 "register_operand"))
(use (match_operand:XF 1 "general_operand"))
(use (match_operand:XF 2 "general_operand"))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
{
rtx_code_label *label = gen_label_rtx ();
@@ -13845,7 +13847,8 @@
[(use (match_operand:MODEF 0 "register_operand"))
(use (match_operand:MODEF 1 "general_operand"))
(use (match_operand:MODEF 2 "general_operand"))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
{
rtx (*gen_truncxf) (rtx, rtx);
@@ -13884,7 +13887,8 @@
(set (reg:CCFP FPSR_REG)
(unspec:CCFP [(match_dup 2) (match_dup 3)]
UNSPEC_C2_FLAG))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
"fprem1"
[(set_attr "type" "fpspc")
(set_attr "mode" "XF")])
@@ -13893,7 +13897,8 @@
[(use (match_operand:XF 0 "register_operand"))
(use (match_operand:XF 1 "general_operand"))
(use (match_operand:XF 2 "general_operand"))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
{
rtx_code_label *label = gen_label_rtx ();
@@ -13916,7 +13921,8 @@
[(use (match_operand:MODEF 0 "register_operand"))
(use (match_operand:MODEF 1 "general_operand"))
(use (match_operand:MODEF 2 "general_operand"))]
- "TARGET_USE_FANCY_MATH_387"
+ "TARGET_USE_FANCY_MATH_387
+ && flag_finite_math_only"
{
rtx (*gen_truncxf) (rtx, rtx);
