On 26 June 2012 00:48, Nathanaël Prémillieu <nprem...@irisa.fr> wrote: > Hi all, > > I am using the gcc ARM cross-compiler (gcc version 4.6.3 (Ubuntu/Linaro > 4.6.3-1ubuntu5)). Compiling the test.c code (in attachement) with: > > 'arm-linux-gnueabi-gcc -S test.c' > > I obtain the test.s assembly code (in attachement). At lines 56 and 57 of > the test.s there is two identical strd instructions: > > 56 strd r2, [r7] > 57 strd r2, [r7] > > I have checked the semantic of the ARM strd instruction and I have not seen > any side effect of this instruction that could explain why gcc need to put > this instruction two times in a row. For me, one is sufficient to store the > 8-bytes variable into memory. > > Is there an explanation?
Hi Nathanaël. Your question is more appropriate for the gcc-help list. This list is about the development of GCC itself. You've built with optimisation turned off so GCC has generated correct but inefficient code. The double store could be side effect of expanding the 64 bit multiply into the component 32 bit multiplies or the conditional. Try building at -O or higher. -- Michael
