This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Fix powerpc round, roundf spurious "inexact" (bug 19238) [committed]
- From: Joseph Myers <joseph at codesourcery dot com>
- To: <libc-alpha at sourceware dot org>
- Date: Thu, 12 Nov 2015 19:00:42 +0000
- Subject: Fix powerpc round, roundf spurious "inexact" (bug 19238) [committed]
- Authentication-results: sourceware.org; auth=none
The powerpc hard-float round and roundf functions, both 32-bit and
64-bit, raise spurious "inexact" exceptions for integer arguments from
adding 0.5 and rounding to integer toward zero.
Since these functions already save and restore the rounding mode, it's
natural to make them restore the full floating-point state instead to
fix this bug, which this patch does. The save of the state is moved
after the first floating-point operation on the input so that any
"invalid" exceptions from signaling NaN inputs are properly
preserved. As a consequence of this approach to the fix, "inexact"
for noninteger arguments (disallowed by TS 18661-1 but not by C99/C11,
see bug 15479) is also avoided for these implementations; this is
*not* a general fix for bug 15479 since plenty of other
implementations of various functions still raise spurious "inexact"
for noninteger arguments.
This issue and fix do not apply to builds using power5+ versions of
round and roundf, which use the frin instruction and avoid "inexact"
exceptions that way.
This patch should get hard-float powerpc32 and powerpc64 (default
function implementations) back to a state where test-float and
test-double will pass after ulps regeneration.
Tested for powerpc32 and powerpc64. Committed.
2015-11-12 Joseph Myers <joseph@codesourcery.com>
[BZ #15479]
[BZ #19238]
* sysdeps/powerpc/powerpc32/fpu/s_round.S (__round): Save
floating-point state after first operation on input. Restore full
state rather than just rounding mode.
* sysdeps/powerpc/powerpc32/fpu/s_roundf.S (__roundf): Likewise.
* sysdeps/powerpc/powerpc64/fpu/s_round.S (__round): Likewise.
* sysdeps/powerpc/powerpc64/fpu/s_roundf.S (__roundf): Likewise.
diff --git a/sysdeps/powerpc/powerpc32/fpu/s_round.S b/sysdeps/powerpc/powerpc32/fpu/s_round.S
index 061fbe2..18ba18a 100644
--- a/sysdeps/powerpc/powerpc32/fpu/s_round.S
+++ b/sysdeps/powerpc/powerpc32/fpu/s_round.S
@@ -38,7 +38,6 @@
.section ".text"
ENTRY (__round)
- mffs fp11 /* Save current FPU rounding mode. */
#ifdef SHARED
mflr r11
cfi_register(lr,r11)
@@ -55,6 +54,8 @@ ENTRY (__round)
fabs fp0,fp1
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
+ mffs fp11 /* Save current FPU rounding mode and
+ "inexact" state. */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnllr- cr7
mtfsfi 7,1 /* Set rounding mode toward 0. */
@@ -70,7 +71,8 @@ ENTRY (__round)
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) */
/* x = 0.0; */
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
.L4:
fsub fp9,fp1,fp10 /* x+= 0.5; */
@@ -80,7 +82,8 @@ ENTRY (__round)
fnabs fp1,fp1 /* if (x == 0.0) */
/* x = -0.0; */
.L9:
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
END (__round)
diff --git a/sysdeps/powerpc/powerpc32/fpu/s_roundf.S b/sysdeps/powerpc/powerpc32/fpu/s_roundf.S
index 414bede..e69a823 100644
--- a/sysdeps/powerpc/powerpc32/fpu/s_roundf.S
+++ b/sysdeps/powerpc/powerpc32/fpu/s_roundf.S
@@ -37,7 +37,6 @@
.section ".text"
ENTRY (__roundf )
- mffs fp11 /* Save current FPU rounding mode. */
#ifdef SHARED
mflr r11
cfi_register(lr,r11)
@@ -54,6 +53,8 @@ ENTRY (__roundf )
fabs fp0,fp1
fsubs fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO23) */
+ mffs fp11 /* Save current FPU rounding mode and
+ "inexact" state. */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnllr- cr7
mtfsfi 7,1 /* Set rounding mode toward 0. */
@@ -68,7 +69,8 @@ ENTRY (__roundf )
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fabs fp1,fp1 /* if (x == 0.0) */
/* x = 0.0; */
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
.L4:
fsubs fp9,fp1,fp10 /* x+= 0.5; */
@@ -78,7 +80,8 @@ ENTRY (__roundf )
fnabs fp1,fp1 /* if (x == 0.0) */
/* x = -0.0; */
.L9:
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
END (__roundf)
diff --git a/sysdeps/powerpc/powerpc64/fpu/s_round.S b/sysdeps/powerpc/powerpc64/fpu/s_round.S
index 2f99c04..31ede39 100644
--- a/sysdeps/powerpc/powerpc64/fpu/s_round.S
+++ b/sysdeps/powerpc/powerpc64/fpu/s_round.S
@@ -38,11 +38,12 @@
EALIGN (__round, 4, 0)
CALL_MCOUNT 0
- mffs fp11 /* Save current FPU rounding mode. */
lfd fp13,.LC0@toc(2)
fabs fp0,fp1
fsub fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
+ mffs fp11 /* Save current FPU rounding mode and
+ "inexact" state. */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnllr- cr7
mtfsfi 7,1 /* Set rounding mode toward 0. */
@@ -53,7 +54,8 @@ EALIGN (__round, 4, 0)
fsub fp1,fp1,fp13 /* x-= TWO52; */
fabs fp1,fp1 /* if (x == 0.0) */
/* x = 0.0; */
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
.L4:
fsub fp9,fp1,fp10 /* x+= 0.5; */
@@ -63,7 +65,8 @@ EALIGN (__round, 4, 0)
fnabs fp1,fp1 /* if (x == 0.0) */
/* x = -0.0; */
.L9:
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
END (__round)
diff --git a/sysdeps/powerpc/powerpc64/fpu/s_roundf.S b/sysdeps/powerpc/powerpc64/fpu/s_roundf.S
index babb52b..3ccf48c 100644
--- a/sysdeps/powerpc/powerpc64/fpu/s_roundf.S
+++ b/sysdeps/powerpc/powerpc64/fpu/s_roundf.S
@@ -39,11 +39,12 @@
EALIGN (__roundf, 4, 0)
CALL_MCOUNT 0
- mffs fp11 /* Save current FPU rounding mode. */
lfs fp13,.LC0@toc(2)
fabs fp0,fp1
fsubs fp12,fp13,fp13 /* generate 0.0 */
fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO23) */
+ mffs fp11 /* Save current FPU rounding mode and
+ "inexact" state. */
fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
bnllr- cr7
mtfsfi 7,1 /* Set rounding mode toward 0. */
@@ -54,7 +55,8 @@ EALIGN (__roundf, 4, 0)
fsubs fp1,fp1,fp13 /* x-= TWO23; */
fabs fp1,fp1 /* if (x == 0.0) */
/* x = 0.0; */
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
.L4:
fsubs fp9,fp1,fp10 /* x+= 0.5; */
@@ -64,7 +66,8 @@ EALIGN (__roundf, 4, 0)
fnabs fp1,fp1 /* if (x == 0.0) */
/* x = -0.0; */
.L9:
- mtfsf 0x01,fp11 /* restore previous rounding mode. */
+ mtfsf 0xff,fp11 /* Restore previous rounding mode and
+ "inexact" state. */
blr
END (__roundf)
--
Joseph S. Myers
joseph@codesourcery.com