Updates:
Status: Assigned
Comment #5 on issue 2205 by [email protected]: MathFloorOfDiv
optimization is very fragile
http://code.google.com/p/v8/issues/detail?id=2205
I just checked it for
function foo(x, y) {
return Math.floor((x + y) / 2);
}
foo(1, 11);
foo(1, 11);
foo(1, 11);
%OptimizeFunctionOnNextCall(foo);
foo(1, 11);
and got:
;;; <@18,#25> tagged-to-i
0x3d32cdcb 43 f6c101 test_b cl,0x1
0x3d32cdce 46 0f8566000000 jnz 154 (0x3d32ce3a)
0x3d32cdd4 52 d1f9 sar ecx,1
;;; <@19,#25> gap
0x3d32cdd6 54 8b5508 mov edx,[ebp+0x8]
;;; <@20,#26> tagged-to-i
0x3d32cdd9 57 f6c201 test_b dl,0x1
0x3d32cddc 60 0f8587000000 jnz 201 (0x3d32ce69)
0x3d32cde2 66 d1fa sar edx,1
;;; <@22,#14> add-i
0x3d32cde4 68 03d1 add edx,ecx
0x3d32cde6 70 0f8013010000 jo 351 (0x3d32ceff)
;;; <@24,#17> div-i
0x3d32cdec 76 f6c201 test_b dl,0x1
0x3d32cdef 79 0f850f010000 jnz 356 (0x3d32cf04)
0x3d32cdf5 85 d1fa sar edx,1
;;; <@26,#19> check-non-smi
0x3d32cdf7 87 f7c001000000 test eax,0x1
0x3d32cdfd 93 0f8406010000 jz 361 (0x3d32cf09)
;;; <@28,#20> check-maps
0x3d32ce03 99 8178ff49db6025 cmp [eax+0xff],0x2560db49 ;; object:
0x2560db49 <Map(elements=3)>
0x3d32ce0a 106 0f85fe000000 jnz 366 (0x3d32cf0e)
;;; <@30,#27> int32-to-double
0x3d32ce10 112 f20f2aca cvtsi2sd xmm1,edx
;;; <@32,#21> math-floor
0x3d32ce14 116 660f3a0bc109 roundsd xmm0,xmm1,9
0x3d32ce1a 122 f20f2cc8 cvttsd2si ecx,xmm0
0x3d32ce1e 126 81f900000080 cmp ecx,0x80000000
0x3d32ce24 132 0f84e9000000 jz 371 (0x3d32cf13)
;;; <@34,#28> number-tag-i
0x3d32ce2a 138 03c9 add ecx,ecx
0x3d32ce2c 140 0f8066000000 jo 248 (0x3d32ce98)
so it was either not fixed or regressed since June.
--
You received this message because this project is configured to send all
issue notifications to this address.
You may adjust your notification preferences at:
https://code.google.com/hosting/settings
--
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
---
You received this message because you are subscribed to the Google Groups "v8-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/groups/opt_out.
