Commit Graph

12 Commits

Author SHA1 Message Date
Craig Topper 74c10e3236 [Builtins][Attributes][X86] Tag all X86 builtins with their required vector width. Add a min_vector_width function attribute and tag all x86 instrinsics with it
This is part of an ongoing attempt at making 512 bit vectors illegal in the X86 backend type legalizer due to CPU frequency penalties associated with wide vectors on Skylake Server CPUs. We want the loop vectorizer to be able to emit IR containing wide vectors as intermediate operations in vectorized code and allow these wide vectors to be legalized to 256 bits by the X86 backend even though we are targetting a CPU that supports 512 bit vectors. This is similar to what happens with an AVX2 CPU, the vectorizer can emit wide vectors and the backend will split them. We want this splitting behavior, but still be able to use new Skylake instructions that work on 256-bit vectors and support things like masking and gather/scatter.

Of course if the user uses explicit vector code in their source code we need to not split those operations. Especially if they have used any of the 512-bit vector intrinsics from immintrin.h. And we need to make it so that merely using the intrinsics produces the expected code in order to be backwards compatible.

To support this goal, this patch adds a new IR function attribute "min-legal-vector-width" that can indicate the need for a minimum vector width to be legal in the backend. We need to ensure this attribute is set to the largest vector width needed by any intrinsics from immintrin.h that the function uses. The inliner will be reponsible for merging this attribute when a function is inlined. We may also need a way to limit inlining in the future as well, but we can discuss that in the future.

To make things more complicated, there are two different ways intrinsics are implemented in immintrin.h. Either as an always_inline function containing calls to builtins(can be target specific or target independent) or vector extension code. Or as a macro wrapper around a taget specific builtin. I believe I've removed all cases where the macro was around a target independent builtin.

To support the always_inline function case this patch adds attribute((min_vector_width(128))) that can be used to tag these functions with their vector width. All x86 intrinsic functions that operate on vectors have been tagged with this attribute.

To support the macro case, all x86 specific builtins have also been tagged with the vector width that they require. Use of any builtin with this property will implicitly increase the min_vector_width of the function that calls it. I've done this as a new property in the attribute string for the builtin rather than basing it on the type string so that we can opt into it on a per builtin basis and avoid any impact to target independent builtins.

There will be future work to support vectors passed as function arguments and supporting inline assembly. And whatever else we can find that isn't covered by this patch.

Special thanks to Chandler who suggested this direction and reviewed a preview version of this patch. And thanks to Eric Christopher who has had many conversations with me about this issue.

Differential Revision: https://reviews.llvm.org/D48617

llvm-svn: 336583
2018-07-09 19:00:16 +00:00
Martin Storsjo cad7a5f1aa [X86] Remove leftover semicolons at end of macros
This was missed in a few places in SVN r333613, causing compilation
errors if these macros are used e.g. as parameter to a function.

llvm-svn: 333734
2018-06-01 09:40:50 +00:00
Craig Topper c633867944 [X86] Remove __extension__ from macro intrinsics when its not needed.
I think this is a holdover from when we used to declare variables inside the macros. And then its been copy and pasted forward for years every time a new macro intrinsic gets added.

Interestingly this caused some tests for IRGen to be slightly more optimized. We now return a zeroinitializer directly instead of going through a store+load.

It also removed a bogus error message on another test.

llvm-svn: 333613
2018-05-31 00:51:20 +00:00
Craig Topper d619eaaae4 [X86] Add missing typecasts in intrinsic macros. This should make them more robust against inputs that aren't already the right type.
llvm-svn: 252700
2015-11-11 03:47:10 +00:00
Michael Kuperstein e45af54cdb [X86] Rename DEFAULT_FN_ATTR macro to __DEFAULT_FN_ATTR
llvm-svn: 241065
2015-06-30 13:36:19 +00:00
Eric Christopher 9fc7fb274e Update the intel intrinsic headers to use the target attribute support.
This involved removing the conditional inclusion and replacing them
with target attributes matching the original conditional inclusion
and checks. The testcase update removes the macro checks for each
file and replaces them with usage of the __target__ attribute, e.g.:

int __attribute__((__target__(("sse3")))) foo(int a) {
  _mm_mwait(0, 0);
  return 4;
}

This usage does require the enclosing function have the requisite
__target__ attribute for inlining and code generation - also for
any macro intrinsic uses in the enclosing function. There's no change
for existing uses of the intrinsic headers.

llvm-svn: 239883
2015-06-17 07:09:32 +00:00
Eric Christopher 4d185168e9 Use a define for per-file function attributes for the Intel intrinsic headers.
This is a precursor to changing them to use the new target attribute
code.

llvm-svn: 239882
2015-06-17 07:09:20 +00:00
Chandler Carruth 28daca211c [x86] Also add the missing type casts on the returns in the sha
intrinsic header file. Along with r224822, this should restore the build
bots to passing.

llvm-svn: 224883
2014-12-27 11:50:51 +00:00
Craig Topper ab70789199 [x86] Add missing typecast to __v4si to sha intrinsic header file.
llvm-svn: 224882
2014-12-27 07:19:25 +00:00
Ben Langmuir ed6e97d2c3 Fix ifdef macro missed in previous commit
llvm-svn: 191003
2013-09-19 14:07:14 +00:00
Ben Langmuir 6efe3a886e Move sha intrinsics to immintrin.h
This is consistent with ICC and Intel's SHA-enabled GCC version.

llvm-svn: 191002
2013-09-19 14:00:22 +00:00
Ben Langmuir 58078d0103 Add C intrinsics for Intel SHA Extensions
Intrinsics added shaintrin.h, which is included from x86intrin.h if __SHA__ is
enabled. SHA implies SSE2, which is needed for the __m128i type.

Also add the -msha/-mno-sha option.

llvm-svn: 190999
2013-09-19 13:22:04 +00:00