Since we permit using SOME attributes (at the moment, just 1) with
multiversioning, we should improve the message as it still implies that
no attributes should be combined with multiversioning.
I discovered that in ICC (where this list comes from), that the two
pentium_iii versions were actually identical despite the two different
names (despite them implying a difference). Because of this, they ended
up having identical manglings, which obviously caused problems when used
together.
This patch makes pentium_iii_no_xmm_regs an alias for pentium_iii so
that it can still be used, but has the same meaning as ICC. However, we
still prohibit using the two together which is different (albeit better)
behavior.
Change-Id: I4f3c9a47e48490c81525c8a3d23ed4201921b288
llvm-svn: 352054
r347812 permitted forward declarations for cpu-dispatch functions, which
are occassionally useful as exposition in header files. However, this inadvertently
permitted this function to become multiversioned after a usage. This
patch ensures that the "CausesMV" checks are still run in the
forward-declaration case.
Change-Id: Icb6f975a2d068f088b89e3bbe26cf1d24f5a972c
llvm-svn: 351212
CPUSpecifc/CPUDispatch call resolution assumed that all declarations
that would be passed are valid, however this was an invalid assumption.
This patch deals with those situations by making the valid version take
priority. Note that the checked ordering is arbitrary, since both are
replaced by calls to the resolver later.
Change-Id: I7ff2ec88c55a721d51bc1f39ea1a1fe242b4e45f
llvm-svn: 350398
As a followup to r347805, allow forward declarations of cpu-dispatch and
cpu-specific for the same reasons.
Change-Id: Ic1bde9be369b1f8f1d47d58e6fbdc2f9dfcdd785
llvm-svn: 347812
As documented here: https://software.intel.com/en-us/node/682969 and
https://software.intel.com/en-us/node/523346. cpu_dispatch multiversioning
is an ICC feature that provides for function multiversioning.
This feature is implemented with two attributes: First, cpu_specific,
which specifies the individual function versions. Second, cpu_dispatch,
which specifies the location of the resolver function and the list of
resolvable functions.
This is valuable since it provides a mechanism where the resolver's TU
can be specified in one location, and the individual implementions
each in their own translation units.
The goal of this patch is to be source-compatible with ICC, so this
implementation diverges from the ICC implementation in a few ways:
1- Linux x86/64 only: This implementation uses ifuncs in order to
properly dispatch functions. This is is a valuable performance benefit
over the ICC implementation. A future patch will be provided to enable
this feature on Windows, but it will obviously more closely fit ICC's
implementation.
2- CPU Identification functions: ICC uses a set of custom functions to identify
the feature list of the host processor. This patch uses the cpu_supports
functionality in order to better align with 'target' multiversioning.
1- cpu_dispatch function def/decl: ICC's cpu_dispatch requires that the function
marked cpu_dispatch be an empty definition. This patch supports that as well,
however declarations are also permitted, since the linker will solve the
issue of multiple emissions.
Differential Revision: https://reviews.llvm.org/D47474
llvm-svn: 337552
Erich Keane