push dword [esp+4] ; push y push dword [esp+4] ; push z call bar add esp, 8 ; cdecl requires caller See pdf. System V Application Binary Interface – Intel™ Architecture Processor Supplement, Fourth Edition, a bit and a bit version. The bit version of standard can be found at and the 64bit version.

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Comment 3 Alexandre Pereira Nunes Page where function calling, including argument passing, begins.

linux – C calling conventions and passed arguments – Stack Overflow

At least sysv abi as far as I’ve read does not mandate anything about the bitfields within a word. Comment 4 Alexandre Pereira Nunes But the request for better documentation is correct. I do believe that Abi3886 structures are always padded alignedand the packed structures are outside of the ABI scope Is it a default on gcc whenever the target has no particular semantics as arm-elf, which I suppose does not derive from the ARM published Ab386 at all?

When a bit-field is inserted into a packed record, the whole size of the underlying type is used by one or more same-size adjacent bit-fields that is, if its long: Although the caller in some calling conventions is the one that cleans up the arguments, all it’s really doing is deallocating bai386 space previously allocated on the stack to hold the argument values.


I ahi386 perfectly that avi386 structures like that is meant to be non-portable, but it’s quite handy to have something like that without too much worry about platforms, since altough I develop for several arches, almost all of them today have a gcc port, and I know there are others with similar issues.

Any changes the called variable makes will be to the original variable in the calling program. Comment 8 Alexandre Pereira Nunes That is where the calling convention comes in.

How have functions like printf been designed so people can easily call them with varying numbers of parameters?

I am talking about the actual, runtime stack parameters at the machine level and whether or not those stack locations can be modified be the callee. Did the behavior change I think it did for some 3. When making a function call in Linux or OS X for that mattercan the callee modify the values of the arguments on the stack?

Called function needs to “know” ai386 many parameters to use. Actually, this was from the compiler I was working on, but I was stashing a value that is live later on in the program. If this hook returns true, other macros that control bit-field layout are ignored.


Index of /elf

Comment 10 Alexandre Pereira Nunes Apply principles learned in courses like CSI Other bug subscribers Subscribe someone else. I’ve seem that gcc packs structures in a very similar if not identical fashion on some targets ixlinux-gnu, arm-elf, mingw without -mms-bitfields, at leastare they covered by sysv ABI too?

The caller does clean them up but ignores the value. Lara Dougan 3 Remote bug watches auto-lsbbugs.

Home New Browse Search [? In case it is, could someone ani386 point me to a documentation source, i. Stack Overflow works best with JavaScript enabled. Right, in that case you can definitely not assume that the popped value will always equal what you previously pushed.

That’s where I said the abi could change for several arches. This bug affects 1 person. Here is some sample code I was debugging. So what I’m asking is: It’s stated somewhere in gcc docs that gcc tries to do things uniformly, only diverging between targets where there’s a compelling reason to do so.