Messages in this thread | | | Date | Mon, 24 Nov 2008 16:28:13 +0200 | From | Török Edwin <> | Subject | 2.6.28-rc6-tip fails to build with gcc 4.4.0 |
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Hi,
Using gcc version 4.4.0 20081120 (experimental) [trunk revision 142055] I can't build latest tip/master (commit b27fef5b222564b6e7ae71f7110c233b2fb45a38)
drivers/built-in.o: In function `sd_revalidate_disk': sd.c:(.text+0x8bc76): undefined reference to `____ilog2_NaN' make: *** [.tmp_vmlinux1] Error 1
Apparently gcc determines that sector_size can have an invalid constant value as ilog2's parameter in sd_read_capacity.
I tried to narrow down, but all I found so far is that gcc 4.4.0 now says that __builtin_constant_p() is true even in these cases:
a = .. constant value ... if (cond) { a = ... constant value ... } __builtin_constant_p(a) ? ....
a = .. constant value ... if (cond) { a = ... constant value ... } else { a = ... another constant value ... } __builtin_constant_p(a) ? ....
I guess it clones the __builtin_constant_p for each branch, where a is constant, gcc 4.3 doesn't seem to do that.
Did it find a real bug in sd.c, or is it a gcc bug?
Best regards, --Edwin
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