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authorJoseph Myers <joseph@codesourcery.com>2015-10-14 21:13:42 +0000
committerJoseph Myers <joseph@codesourcery.com>2015-10-14 21:13:42 +0000
commit0c25f5b5bb48a9d550b5fb403b9a801ba04c146f (patch)
tree1924b1f2087eacccee4837bcdbf16f8dad8d0814 /sysdeps/powerpc
parent1fae5a6800b07d0a8225664ac65a628bbe98cae7 (diff)
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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.
Diffstat (limited to 'sysdeps/powerpc')
-rw-r--r--sysdeps/powerpc/powerpc32/fpu/s_lround.S43
1 files changed, 41 insertions, 2 deletions
diff --git a/sysdeps/powerpc/powerpc32/fpu/s_lround.S b/sysdeps/powerpc/powerpc32/fpu/s_lround.S
index 231d5e4..5dd3618 100644
--- 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)