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Cherry Zhang 49e933fc57 cmd/compile: make interface conversion function selection ABI insensitive
Before register ABI, we always pass argument in memory, and the
compiler chooses interface conversion functions solely based on
the memory layout. As long as the two types have identical memory
layout, it is fine to mix and match, e.g. convT64 takes a uint64
argument, but it can be used for things like float64 or
struct { x [4]struct{}; y int64 }.

With register ABI, those types may be passed differently, e.g.
uint64 is passed in an integer register, float64 is passed in a
floating point register, the struct above is passed in memory.
I made a few attempts in the previous CLs to try to choose the
right function based on the argument type, but none of them is
really correct.

Instead, this CL changes it to always pass the argument in the
same type the runtime expects, and do conversion before the call
in the compiler. The conversion can be no-op (e.g. a named type
to its underlying type), direct (e.g. int64 to uint64), or
through memory (e.g. *(*uint64)(unsafe.Pointer(&arg))). This way,
the front end does not need to know the ABI. (It only needs to
know how to convert types, and it already does.)

TODO: do something similar for map functions.

Change-Id: I33fc780a47c3f332b765e09b5e527f52ea1d6b5c
Reviewed-on: https://go-review.googlesource.com/c/go/+/309029
Trust: Cherry Zhang <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
2021-04-12 22:50:31 +00:00
.github .github: add link to questions in ISSUE_TEMPLATE 2020-01-06 17:05:31 +00:00
api syscall: restore broken GetQueuedCompletionStatus signature but make it not crash 2021-02-24 23:35:00 +00:00
doc runtime/cgo: add Handle for managing (c)go pointers 2021-04-06 23:39:42 +00:00
lib/time lib/time, time/tzdata: update tzdata to 2021a 2021-01-25 16:08:46 +00:00
misc all: fix spellings 2021-04-10 01:46:41 +00:00
src cmd/compile: make interface conversion function selection ABI insensitive 2021-04-12 22:50:31 +00:00
test test: make codegen tests work with both ABIs 2021-04-12 21:59:59 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore
AUTHORS A+C: add new e-mail addresses for Andy Pan 2021-03-12 02:56:04 +00:00
CONTRIBUTING.md all: restore changes from faulty merge/revert 2018-02-12 20:13:59 +00:00
CONTRIBUTORS A+C: add new e-mail addresses for Andy Pan 2021-03-12 02:56:04 +00:00
LICENSE
PATENTS
README.md README: pull gopher image from website 2021-02-16 18:25:10 +00:00
SECURITY.md SECURITY.md: update go versions 2019-09-26 15:34:57 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00

README.md

The Go Programming Language

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