Somewhere in the process of writing the documentation for the ms_abi
function attribute, there has been some (justifiable) confusion about
which calling conventions are which, and the documentation currently
states that on non-Windows x86 targets we default to the "x86/AMD ABI".
In the past I've heard "the AMD calling conventions" used to refer to
the Microsoft parameter passing register usage, so I looked it up. As
far as I can tell, AMD does not specify *any* calling conventions for
the 64-bit x86 instruction set. The only times the AMD64 documentation
refers to calling conventions or parameter passing are in a general
introduction of PUSHA and ENTER, which do not implement a relevant part
of either convention, and a section about saving SSE state when passing
YMM/XMM register values as arguments.
This patch changes the documentation to explicitly refer to either the
"Microsoft ABI" or the "System V ELF ABI".
Signed-off-by: Peter Jones <pjo...@redhat.com>
---
ChangeLog | 5 +++++
gcc/doc/extend.texi | 7 ++++---
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index b0239316868..691d4cd619c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2020-09-10 Peter Jones <pjo...@redhat.com>
+
+ * gcc/doc/extend.texi: Clarify the documentation for the ms_abi
+ function attribute
+
2020-08-26 Tobias Burnus <tob...@codesourcery.com>
* MAINTAINERS (Various Maintainers): Add myself as OpenACC maintainer.
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 3b37aba5795..8ac4dad390f 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -6069,9 +6069,10 @@ and for static member methods.
On 32-bit and 64-bit x86 targets, you can use an ABI attribute
to indicate which calling convention should be used for a function. The
@code{ms_abi} attribute tells the compiler to use the Microsoft ABI,
-while the @code{sysv_abi} attribute tells the compiler to use the ABI
-used on GNU/Linux and other systems. The default is to use the Microsoft ABI
-when targeting Windows. On all other systems, the default is the x86/AMD ABI.
+while the @code{sysv_abi} attribute tells the compiler to use the System V
+ELF ABI, which is used on GNU/Linux and other systems. The default is to use
+the Microsoft ABI when targeting Windows. On all other systems, the default
+is the System V ELF ABI.
Note, the @code{ms_abi} attribute for Microsoft Windows 64-bit targets
currently
requires the @option{-maccumulate-outgoing-args} option.
--
2.26.2
