While looking at the GCC testresults compiled with -mips16 I found that
gcc.target/mips/mips32-dsp-run.c failed.  Further investigation resulted
in this cutdown testcase:


long long a64_r;
unsigned int ui32_a, ui32_b;

__attribute__((nomips16)) int foo() {
a64_r = __builtin_mips_multu (ui32_a, ui32_b);
}

main ()
{
	foo();
}


Compiling with -O3 -mips16 results in:

gcc -mips16 -O3 builtin.c
/local/home/sellcey/nightly_full/install-mips-mti-elf/lib/gcc/mips-mti-elf/4.8.0/../../../../mips-mti-elf/bin/ld: warning: cannot find entry symbol __start; defaulting to 0000000000400098
/tmp/ccrfai7t.o: In function `foo':
builtin.c:(.text+0x10): undefined reference to `__builtin_mips_multu'
collect2: error: ld returned 1 exit status

Inlining a function with the nomips16 attribute into a function that does
not have that attribute seems to be the cause of the problem.