64 bit off-core writes in C

[notzed]

[jeremybennett]

What does -Os or -O2 do? Alternatively put this in a separate file and compile it with -O3 and the rest with -Os.

You can also control the invididual optimizations with the various -f flags. I'll pass this on to Joern Rennecke (who ported GCC) to see if he has any suggestions.

Jeremy

[ysapir]

This problem is known and AFAIR, the only bulletproof solution is to use extended inline assembly for forcing the STRD instruction.

[amylaar]

[amylaar]

P.S.: It would be interesting to hear what experiences people have with -fno-split-wide-types in general.
If the subreg pass does generally more harm than good for epiphany, we can change the default.

[over9000]

Would adding __attribute__((aligned(64)) on the pointer (edit: and struct) cause it to use the correct instruction?

[notzed]

[over9000]

[ysapir]

FYI, in the past, I tried using __builtin_assume_aligned() intrinsic for function arguments, but the results weren't consistent either.

[amylaar]

Epiphany aligns the stack pointer to multiples of 8 bytes. And the biggest alignment for types (in the absence of attributes) is also 64 bit, so that's what long long gets.