>> getcallerpc: >> movl 4(%esp), %eax >> movl -4(%eax), %eax > > Just a thought: this is in the GCC function call context, which is > different from the P9 compilers'. Does the above still apply?
yes, it does. standard x86 gcc and plan 9 use the same conventions for how function arguments get passed. the only difference in calling convention between gcc's default behavior on x86 platforms and the plan 9 compilers is that gcc has a few callee-saved registers, while the plan 9 compilers have none. i don't know whether, in the gcc port for plan 9, david changed the register saving conventions to match plan 9's. i carefully avoided the issue in the snippet above, trashing only the return register %eax. very few programs care if getcallerpc is broken, and it is never a bottleneck. if it is really bothering you, the c function i posted is certainly correct and avoids writing assembly. russ
