On Tue, Aug 2, 2011 at 2:06 PM, Mikael Pettersson <mi...@it.uu.se> wrote: > Michael Walle writes: > > > > Hi, > > > > > To confirm that try -fno-tree-ter. > > > > "lm32-gcc -O1 -fno-tree-ter -S -c test.c" generates the following working > > assembly code: > > > > f2: > > addi sp, sp, -4 > > sw (sp+4), ra > > addi r2, r0, 10 > > calli __ashrsi3 > > addi r8, r0, 10 > > scall > > lw ra, (sp+4) > > addi sp, sp, 4 > > b ra > > -fno-tree-ter also unbreaks the ARM test case in PR48863 comment #4.
It's of course only a workaround, not a real fix as nothing prevents other optimizers from performing the re-scheduling TER does. I suggest to amend the documentation for local call-clobbered register variables to say that the only valid sequence using them is from a non-inlinable function that contains only direct initializations of the register variables from constants or parameters. Or go one step further and deprecate local register variables alltogether (they IMHO don't make much sense, and rather the targets should provide a way to properly constrain asm inputs and outputs). Richard.
