On Mon, Aug 03, 2015 at 02:48:09PM -0700, Steve Ellcey wrote: > When I generate code to dynamically align the stack my code looks like > this: > > fn2: > .frame $fp,32,$31 # vars= 0, regs= 2/0, args= 16, gp= 8 > .mask 0xc0000000,-4 > .fmask 0x00000000,0 > .set noreorder > .set nomacro > lui $2,%hi(null) > li $3,-16 # 0xfffffffffffffff0 > lw $2,%lo(null)($2) > and $sp,$sp,$3 > addiu $sp,$sp,-32 > .cfi_def_cfa_offset 32 > sw $fp,24($sp) > .cfi_offset 30, -8 > move $fp,$sp > .cfi_def_cfa_register 30 > sw $31,28($sp) > .cfi_offset 31, -4 > jal abort > sb $0,0($2) > > The 'and' instruction is where the stack gets aligned and if I remove that > one instruction, everything works. I think I need to put out some new CFI > psuedo-ops to handle this but I am not sure what they should be. I am just > not very familiar with the CFI directives.
I don't speak mips assembly very well, but it looks to me that you have more than just CFI problems. How do you restore sp on return from the function, assuming sp wasn't 16-byte aligned to begin with? Past that "and $sp,$sp,$3" you don't have any means of calculating the original value of sp! (Which of course is why you also can't find a way of representing the frame address.) -- Alan Modra Australia Development Lab, IBM
