mips gcc -O1: Address exception error on store doubleword

[Andrew Haley]

[redirected to gcc-help]

Alex Gonzalez writes:

 > I am seeing an address error exception caused by the gcc optimizer -O1.
 > 
 > I have narrowed it down to the following function:
 > 
 > static void varcopy(PVAR *pvar1, PVAR *pvar2) {
 >     memcpy(pvar1,pvar2,sizeof(PVAR));
 > }
 > 
 > Being the sizeof(PVAR) 160 bytes.
 > 
 > The exception is caused on an sd instruction when the input is not
 > aligned on a doubleword boundary.
 > 
 > I was under the assumption that the compiler made sure that it doesn't
 > store a doubleword that is not aligned on a doubleword boundary. Is
 > this a bug in the optimizer?
 > 
 > I am using a gcc mips64 cross-compiler,
 > 
 > mips64-linux-gnu-gcc (GCC) 3.3-mips64linux-031001
 > 
 > Has anyone experienced this problem before?

I'm guessing you're doing something illegal, like casting an unaligned
pointer to a PVAR *.  It would help if you could post a short test
case (complete, runnable) that shows the problem.

Andrew.