Fix powerpc32 lround, lroundf spurious exceptions (bug 19134).

The powerpc32 implementation of lround and lroundf can produce
spurious exceptions from adding 0.5 then converting to integer.  This
includes "inexact" from the conversion to integer (not allowed for
integer arguments to these functions), and, for larger integer
arguments, "inexact", and "overflow" when rounding upward, from the
addition.  In addition, "inexact" is not allowed together with
"invalid" and so inexact addition must be avoided when the integer
will be out of range of 32-bit long, whether or not the argument is an
integer.

This patch fixes these problems.  As in the powerpc64 llround
implementation, a check is added for too-large arguments; in the
powerpc64 case that means arguments at least 2^52 in magnitude (so
that 0.5 cannot be added exactly), while in this case it means
arguments for which the result would overflow "long".  In those cases
a suitable overflowing value is used for the integer conversion
without adding 0.5, while for smaller arguments it's tested whether
the argument is an integer (by adding and subtracting 2^52 to the
absolute value and comparing with the original absolute value) to
avoid adding 0.5 to integers and generating spurious "inexact".

This code is not used when the power5+ sysdeps directories are used,
as there's a separate power5+ version of these functions..

Tested for powerpc.  This gets test-float (for a default powerpc32
hard-float build without any --with-cpu) back to the point where it
should pass once powerpc ulps are regenerated; test-double still needs
another problem with exceptions fixed to get back to that point (and I
haven't looked lately at what default powerpc64 results are like).

	[BZ #19134]
	* sysdeps/powerpc/powerpc32/fpu/s_lround.S (.LC1): New object.
	(.LC2): Likewise.
	(.LC3): Likewise.
	(__lround): Do not add 0.5 to integer or out-of-range arguments.

diff --git a/ChangeLog b/ChangeLog
index 8a308891ea3d4a7f7487a64147bd13ddc43c11a7..997ad1381f30bd62b79fcd80ddd1149c9022282c 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-10-14  Joseph Myers  <joseph@codesourcery.com>
+
+       [BZ #19134]
+       * sysdeps/powerpc/powerpc32/fpu/s_lround.S (.LC1): New object.
+       (.LC2): Likewise.
+       (.LC3): Likewise.
+       (__lround): Do not add 0.5 to integer or out-of-range arguments.
+
 2015-10-14  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
        [BZ #19129]

diff --git a/NEWS b/NEWS
index fd33e079f6f5082e6ffe61a9d9f2a6899c1ce0ad..d4e8b4adf2e0cfe87fafdc1a4989e6c6e7976c7e 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -20,7 +20,7 @@ Version 2.23
   18966, 18967, 18969, 18970, 18977, 18980, 18981, 18985, 19003, 19007,
   19012, 19016, 19018, 19032, 19046, 19049, 19050, 19059, 19071, 19074,
   19076, 19077, 19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124,
-  19125, 19129
+  19125, 19129, 19134
 
 * The obsolete header <regexp.h> has been removed.  Programs that require
   this header must be updated to use <regex.h> instead.

diff --git a/sysdeps/powerpc/powerpc32/fpu/s_lround.S b/sysdeps/powerpc/powerpc32/fpu/s_lround.S
index 231d5e4f45c0bc96c4692c481a422a546872e306..5dd3618524482b3d3d96fb9278ee1c0fd0665d0b 100644 (file)
--- a/sysdeps/powerpc/powerpc32/fpu/s_lround.S
+++ b/sysdeps/powerpc/powerpc32/fpu/s_lround.S
@@ -23,6 +23,16 @@
        .align  2
 .LC0:  /* 0.5 */
        .long 0x3f000000
+.LC1:  /* 2^52.  */
+       .long 0x59800000
+       .section        .rodata.cst8,"aM",@progbits,8
+       .align  3
+.LC2:  /* 0x7fffffff.8p0.  */
+       .long 0x41dfffff
+       .long 0xffe00000
+.LC3:  /* -0x80000000.8p0.  */
+       .long 0xc1e00000
+       .long 0x00100000
        .section        ".text"
 
 /* long [r3] lround (float x [fp1])
@@ -45,19 +55,40 @@ ENTRY (__lround)
        mflr    r11
        cfi_register(lr,r11)
        SETUP_GOT_ACCESS(r9,got_label)
-       addis   r9,r9,.LC0-got_label@ha
-       lfs     fp10,.LC0-got_label@l(r9)
+       addis   r10,r9,.LC0-got_label@ha
+       lfs     fp10,.LC0-got_label@l(r10)
+       addis   r10,r9,.LC1-got_label@ha
+       lfs     fp11,.LC1-got_label@l(r10)
+       addis   r10,r9,.LC2-got_label@ha
+       lfd     fp9,.LC2-got_label@l(r10)
+       addis   r10,r9,.LC3-got_label@ha
+       lfd     fp8,.LC3-got_label@l(r10)
        mtlr    r11
        cfi_same_value (lr)
 #else
        lis     r9,.LC0@ha
        lfs     fp10,.LC0@l(r9)
+       lis     r9,.LC1@ha
+       lfs     fp11,.LC1@l(r9)
+       lis     r9,.LC2@ha
+       lfd     fp9,.LC2@l(r9)
+       lis     r9,.LC3@ha
+       lfd     fp8,.LC3@l(r9)
 #endif
        fabs    fp2, fp1        /* Get the absolute value of x.  */
        fsub    fp12,fp10,fp10  /* Compute 0.0.  */
        fcmpu   cr6, fp2, fp10  /* if |x| < 0.5  */
+       fcmpu   cr5, fp1, fp9   /* if x >= 0x7fffffff.8p0  */
+       fcmpu   cr1, fp1, fp8   /* if x <= -0x80000000.8p0  */
        fcmpu   cr7, fp1, fp12  /* x is negative? x < 0.0  */
        blt-    cr6,.Lretzero
+       bge-    cr5,.Loflow
+       ble-    cr1,.Loflow
+       /* Test whether an integer to avoid spurious "inexact".  */
+       fadd    fp3,fp2,fp11
+       fsub    fp3,fp3,fp11
+       fcmpu   cr5, fp2, fp3
+       beq     cr5,.Lnobias
        fadd    fp3,fp2,fp10    /* |x|+=0.5 bias to prepare to round.  */
        bge     cr7,.Lconvert   /* x is positive so don't negate x.  */
        fnabs   fp3,fp3         /* -(|x|+=0.5)  */
@@ -74,6 +105,14 @@ ENTRY (__lround)
 .Lretzero:                     /* when 0.5 > x > -0.5  */
        li      r3,0            /* return 0.  */
        b       .Lout
+.Lnobias:
+       fmr     fp3,fp1
+       b       .Lconvert
+.Loflow:
+       fmr     fp3,fp11
+       bge     cr7,.Lconvert
+       fnabs   fp3,fp3
+       b       .Lconvert
        END (__lround)
 
 weak_alias (__lround, lround)