On modern Intel processors hardware SQRT in many cases is faster than RSQRT
followed by Newton-Raphson refinement. The patch introduces a simple heuristic
to choose between hardware SQRT instruction and Newton-Raphson software
estimation.
The patch treats scalars and vectors differently. The heuristic is that for
scalars the compiler should optimize for latency while for vectors it should
optimize for throughput. It is based on the assumption that throughput bound
code is likely to be vectorized.
Basically, the patch disables scalar NR for big cores and disables NR completely
for Skylake. Firstly, scalar SQRT has shorter latency than NR code in big cores.
Secondly, vector SQRT has been greatly improved in Skylake and has better
throughput compared to NR.
Differential Revision: https://reviews.llvm.org/D21379
llvm-svn: 277725
Summary:
MONITORX/MWAITX instructions provide similar capability to the MONITOR/MWAIT
pair while adding a timer function, such that another termination of the MWAITX
instruction occurs when the timer expires. The presence of the MONITORX and
MWAITX instructions is indicated by CPUID 8000_0001, ECX, bit 29.
The MONITORX and MWAITX instructions are intercepted by the same bits that
intercept MONITOR and MWAIT. MONITORX instruction establishes a range to be
monitored. MWAITX instruction causes the processor to stop instruction execution
and enter an implementation-dependent optimized state until occurrence of a
class of events.
Opcode of MONITORX instruction is "0F 01 FA". Opcode of MWAITX instruction is
"0F 01 FB". These opcode information is used in adding tests for the
disassembler.
These instructions are enabled for AMD's bdver4 architecture.
Patch by Ganesh Gopalasubramanian!
Reviewers: echristo, craig.topper, RKSimon
Subscribers: RKSimon, joker.eph, llvm-commits
Differential Revision: http://reviews.llvm.org/D19795
llvm-svn: 269911
For compilations with no explicit cpu specified, this exhibits
nice gains on Silvermont, with neutral performance on big cores.
Differential Revision: http://reviews.llvm.org/D19138
llvm-svn: 267809
btver1 is a SSSE3/SSE4a only CPU - it doesn't have AVX and doesn't support XSAVE.
Differential Revision: http://reviews.llvm.org/D17683
llvm-svn: 262782
Summary:
- Rename `"skylake"` == SkylakeServerProc to `"skylake-avx512"`
- Change `"skylake"` to denote SkylakeClientProc
- Fix the detection of cpu family 6 and model 94 to be
SkylakeClientProc instead of SkylakeServerProc
- Remove the `"cnl"` for CannonLake
Reviewers: craig.topper, delena
Subscribers: zansari, echristo, qcolombet, RKSimon, spatel, DavidKreitzer, mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D17090
llvm-svn: 261482
Changes in X86.td:
I set features of Intel processors in incremental form: IVB = SNB + X HSW = IVB + X ..
I added Skylake client processor and defined it's features
FeatureADX was missing on KNL
Added some new features to appropriate processors SMAP, IFMA, PREFETCHWT1, VMFUNC and others
Differential Revision: http://reviews.llvm.org/D16357
llvm-svn: 258659
The feature flag is for VPERMB,VPERMI2B,VPERMT2B and VPMULTISHIFTQB instructions.
More about the instruction can be found in:
hattps://software.intel.com/sites/default/files/managed/07/b7/319433-023.pdf
Differential Revision: http://reviews.llvm.org/D16190
llvm-svn: 258012
the feature flag is essential for RDPKRU and WRPKRU instruction
more about the instruction can be found in the SDM rev 56, vol 2 from http://www.intel.com/sdm
Differential Revision: http://reviews.llvm.org/D15491
llvm-svn: 255644
These instructions are not supported by all CPUs in 64-bit mode. Emitting them
causes Chromium to crash on start-up for users with such chips.
(GCC puts these instructions behind -msahf on 64-bit for the same reason.)
This patch adds FeatureLAHFSAHF, enables it by default for 32-bit targets
and modern CPUs, and changes X86InstrInfo::copyPhysReg back to the lowering
from before r244503 when the instructions are not available.
Differential Revision: http://reviews.llvm.org/D15240
llvm-svn: 254793
its own variable.
This is needed so that we can explicitly turn off MMX without turning
off SSE and also so that we can diagnose feature set incompatibilities
that involve MMX without SSE.
Rationale:
// sse3
__m128d test_mm_addsub_pd(__m128d A, __m128d B) {
return _mm_addsub_pd(A, B);
}
// mmx
void shift(__m64 a, __m64 b, int c) {
_mm_slli_pi16(a, c);
_mm_slli_pi32(a, c);
_mm_slli_si64(a, c);
_mm_srli_pi16(a, c);
_mm_srli_pi32(a, c);
_mm_srli_si64(a, c);
_mm_srai_pi16(a, c);
_mm_srai_pi32(a, c);
}
clang -msse3 -mno-mmx file.c -c
For this code we should be able to explicitly turn off MMX
without affecting the compilation of the SSE3 function and then
diagnose and error on compiling the MMX function.
This matches the existing gcc behavior and follows the spirit of
the SSE/MMX separation in llvm where we can (and do) turn off
MMX code generation except in the presence of intrinsics.
Updated a couple of tests, but primarily tested with a couple of tests
for turning on only mmx and only sse.
This is paired with a patch to clang to take advantage of this behavior.
llvm-svn: 249731
See discussion in D12154 ( http://reviews.llvm.org/D12154 ), AMD Software
Optimization Guides for 10H/12H/15H/16H, and Agner Fog's experimental data.
llvm-svn: 245733
This is a 'no functional change intended' patch. It removes one FIXME, but adds several more.
Motivation: the FeatureFastUAMem attribute may be too general. It is used to determine if any
sized misaligned memory access under 32-bytes is 'fast'. From the added FIXME comments, however,
you can see that we're not consistent about this. Changing the name of the attribute makes it
clearer to see the logic holes.
Changing this to a 'slow' attribute also means we don't have to add an explicit 'fast' attribute
to new chips; fast unaligned accesses have been standard for several generations of CPUs now.
Differential Revision: http://reviews.llvm.org/D12154
llvm-svn: 245729
Adds pushes to the folding tables.
This also required a fix to the TD definition, since the memory forms of
the push instructions did not have the right mayLoad/mayStore flags.
Differential Revision: http://reviews.llvm.org/D11340
llvm-svn: 243010
The first try (r238051) to land this was reverted due to ExecutionEngine build failure;
that was hopefully addressed by r238788.
The second try (r238842) to land this was reverted due to BUILD_SHARED_LIBS failure;
that was hopefully addressed by r238953.
This patch adds a TargetRecip class for processing many recip codegen possibilities.
The class is intended to handle both command-line options to llc as well
as options passed in from a front-end such as clang with the -mrecip option.
The x86 backend is updated to use the new functionality.
Only -mcpu=btver2 with -ffast-math should see a functional change from this patch.
All other x86 CPUs continue to *not* use reciprocal estimates by default with -ffast-math.
Differential Revision: http://reviews.llvm.org/D8982
llvm-svn: 239001
Intel® Memory Protection Extensions (Intel® MPX) is a new feature in Skylake.
It is a part of KNL and SKX sets. It is also a part of Skylake client.
I added definition of %bnd0 - %bnd3 registers, each register is a pair of 64-bit integers.
llvm-svn: 238916
The first try (r238051) to land this was reverted due to bot failures
that were hopefully addressed by r238788.
This patch adds a TargetRecip class for processing many recip codegen possibilities.
The class is intended to handle both command-line options to llc as well
as options passed in from a front-end such as clang with the -mrecip option.
The x86 backend is updated to use the new functionality.
Only -mcpu=btver2 with -ffast-math should see a functional change from this patch.
All other x86 CPUs continue to *not* use reciprocal estimates by default with -ffast-math.
Differential Revision: http://reviews.llvm.org/D8982
llvm-svn: 238842
This patch adds a class for processing many recip codegen possibilities.
The TargetRecip class is intended to handle both command-line options to llc as well
as options passed in from a front-end such as clang with the -mrecip option.
The x86 backend is updated to use the new functionality.
Only -mcpu=btver2 with -ffast-math should see a functional change from this patch.
All other CPUs continue to *not* use reciprocal estimates by default with -ffast-math.
Differential Revision: http://reviews.llvm.org/D8982
llvm-svn: 238051
to use the information in the module rather than TargetOptions.
We've had and clang has used the use-soft-float attribute for some
time now so have the backends set a subtarget feature based on
a particular function now that subtargets are created based on
functions and function attributes.
For the one middle end soft float check go ahead and create
an overloadable TargetLowering::useSoftFloat function that
just checks the TargetSubtargetInfo in all cases.
Also remove the command line option that hard codes whether or
not soft-float is set by using the attribute for all of the
target specific test cases - for the generic just go ahead and
add the attribute in the one case that showed up.
llvm-svn: 237079
r224330 introduced a bug by misinterpreting the "FeatureVectorUAMem" bit.
The commit log says that change did not affect anything, but that's not correct.
That change allowed SSE instructions to have unaligned mem operands folded into
math ops, and that's not allowed in the default specification for any SSE variant.
The bug is exposed when compiling for an AVX-capable CPU that had this feature
flag but without enabling AVX codegen. Another mistake in r224330 was not adding
the feature flag to all AVX CPUs; the AMD chips were excluded.
This is part of the fix for PR22371 ( http://llvm.org/bugs/show_bug.cgi?id=22371 ).
This feature bit is SSE-specific, so I've renamed it to "FeatureSSEUnalignedMem".
Changed the existing test case for the feature bit to reflect the new name and
renamed the test file itself to better reflect the feature.
Added runs to fold-vex.ll to check for the failing codegen.
Note that the feature bit is not set by default on any CPU because it may require a
configuration register setting to enable the enhanced unaligned behavior.
llvm-svn: 227983
According to AVX specification:
"Most arithmetic and data processing instructions encoded using the VEX prefix and
performing memory accesses have more flexible memory alignment requirements
than instructions that are encoded without the VEX prefix. Specifically,
With the exception of explicitly aligned 16 or 32 byte SIMD load/store instructions,
most VEX-encoded, arithmetic and data processing instructions operate in
a flexible environment regarding memory address alignment, i.e. VEX-encoded
instruction with 32-byte or 16-byte load semantics will support unaligned load
operation by default. Memory arguments for most instructions with VEX prefix
operate normally without causing #GP(0) on any byte-granularity alignment
(unlike Legacy SSE instructions)."
The same for AVX-512.
This change does not affect anything right now, because only the "memop pattern fragment"
depends on FeatureVectorUAMem and it is not used in AVX patterns.
All AVX patterns are based on the "unaligned load" anyway.
llvm-svn: 224330
missing barcelona CPU which that test uncovered, and remove the 32-bit
x86 CPUs which I really wasn't prepared to audit and test thoroughly.
If anyone wants to clean up the 32-bit only x86 CPUs, go for it.
Also, if anyone else wants to try to de-duplicate the AMD CPUs, that'd
be cool, but from the looks of it wouldn't save as much as it did for
the Intel CPUs.
llvm-svn: 223774
Notably, this adds simple micro-architecture names for the Intel CPU
variants, and defines the old 'core'-based names as aliases. GCC has
started to simplify their documented interface to use these names as
well, so it seems like we can start to converge on a consistent pattern.
I'd appreciate Intel double checking the entries that aren't yet
documented widely, especially Atom (Bonnell and Silvermont), Knights
Landing, and Skylake. But this change shouldn't break any existing
users.
Also, ran clang-format to re-format this code and it actually worked
(modulo a tiny bug) so hopefully we can start to stop thinking about
formatting this stuff.
llvm-svn: 223769
Allow unaligned 16-byte memop codegen for btver2. No functional changes for any other subtargets.
Replace the existing supposed small memcpy test with an actual test of a small memcpy.
The previous test wasn't using FileCheck either.
This patch should allow us to close PR21541 ( http://llvm.org/bugs/show_bug.cgi?id=21541 ).
Differential Revision: http://reviews.llvm.org/D6360
llvm-svn: 222925
This patch adds a feature flag to avoid unaligned 32-byte load/store AVX codegen
for Sandy Bridge and Ivy Bridge. There is no functionality change intended for
those chips. Previously, the absence of AVX2 was being used as a proxy to detect
this feature. But that hindered codegen for AVX-enabled AMD chips such as btver2
that do not have the 32-byte unaligned access slowdown.
Performance measurements are included in PR21541 ( http://llvm.org/bugs/show_bug.cgi?id=21541 ).
Differential Revision: http://reviews.llvm.org/D6355
llvm-svn: 222544
Nikolai Bozhenov