Issue localized. Surprised that anyone with /W4 /WX on MS VC does not see this,
since this code can be seen by any X64 build that I can try. MSVC detects that
the union of an auto variable exceeds the storage on the stack.
The problem is that word0 uses the following union:
1. typedef union { double d; ULong L[2]; } U; (gdtoaimp.h)
2. Now, ULong is typedef'd to UINTN. (see EfiCdefs.h)
3. word0() is #define word0(x) ( /* LINTED */ (U*)&x)->L[1] (gdtoaimp.h)
4. And rv is a double: double aadj, aadj1, adj, rv, rv0; (strtod.c, line
96) In MSVC, this is 8 bytes.
Now, the line in question is line 825:
825: word0(rv) = (UINT32)(L | Bndry_mask1);
Which ends up being
((U *)&rv)->L[1] = (UINT32)(L | Bndry_mask1);
L[1] ends up being offset 8 (64 bits) into rv, which is past the end of the
double, thus the warning. That explaines why word1(x) works fine.
There is a piece of commented-out code in line 287 of gdatoimp.h which uses a
UINT32 instead of a ULong, which appears to be correct. After commenting out
line 286 and including line 287, the code builds without warning.
Thanks,
Tim
From: Tim Lewis [mailto:tim.le...@insyde.com]
Sent: Monday, October 22, 2012 2:42 PM
To: edk2-devel@lists.sourceforge.net
Subject: [edk2] strod issues
Anyone seen these before? I can get them in one config but not another. In X64
word0 evaluates to a UINTN *
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(825) : error C2220: warning
treated as error - no 'object' file generated
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(825) : warning C4789:
destination of memory copy is too small
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(785) : warning C4789:
destination of memory copy is too small
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(905) : warning C4789:
destination of memory copy is too small
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(499) : warning C4789:
destination of memory copy is too small
d:\bios\kernel\05.02.40\stdlib\libc\gdtoa\strtod.c(473) : warning C4789:
destination of memory copy is too small
They all seem to come from lines like this:
825: word0(rv) = (UINT32)(L | Bndry_mask1);
785: word0(rv) = (word0(rv) & Exp_mask)
+ Exp_msk1
#ifdef IBM
| Exp_msk1 >> 4
#endif
;
905: word0(rv) = Big0;
499: word0(rv) = (P+2)*Exp_msk1;
473: word0(rv) = Big0;
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