https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70047
Bug ID: 70047
Summary: Warn on inefficient function parameter passing
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: jaak at ristioja dot ee
Target Milestone: ---
According to the x86_64 ABI [1], function arguments are passed using registers
and stack memory. It might be useful for x86_64 and other architectures if GCC
would provide an option to warn if some parameters would (inefficiently) be
passed on the stack instead of being passed via registers. This would help
programmers optimize function signatures without disassembling the end result.
Depending on the cost of different argument passing techniques in the ABI used,
this warning option could benefit from multiple levels or suboptions, e.g.
-Wparameter-passing=memory,xmm
would warn if parameters are passed on stack or via xmm registers.
Just a raw idea. :)
[1] System V Application Binary Interface. AMD64 Architecture Processor
Supplement. Draft Version 0.99.6. http://www.x86-64.org/documentation/abi.pdf
