Jakub Jelinek wrote: > On Mon, Jul 04, 2011 at 03:49:58PM +0200, Michael Matz wrote: >> > But you said the operand is an int sized memory, while you expect >> > 4 times as big data with different alignment. >> > So you want "m"(*(__m128d *)nnnn) (or "m"(*(__m128i *)nnnn) ). >> >> Right. But even then the replacement of a memory location with a >> constant >> seems useless in an asm operand whose constraint requires memory. The >> only thing that we get out of this is some shuffling between the old and >> some temporary memory.
I commented on http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46615 about how I patched the mpeg2dec package in mandriva. > No, what you can get out of that is e.g. optimizing away otherwise > unneeded > large variable. > Consider: > static const int i[131072] = { 1, 2, 3, 4, 5 }; > void foo (void) > { > __asm volatile ("" : : "m" (i[0])); > } > By giving the asm just address of an const int 1 instead of the whole > array > you can optimize the large array away. The solution I used was to not declare the vector as const. It probably is a fragile solution, but at the moment I considered safer than attempting to patch the asm, and inserting bugs on code I do not fully understand. > Jakub Paulo
