This patch disables target specific combine on X86ISD::INSERTPS dag nodes
if optlevel is CodeGenOpt::None.
The backend currently implements a target specific combine rule that converts
a vector load used by an INSERTPS dag node into a scalar load plus a
scalar_to_vector. This allows ISel to select a single INSERTPSrm instead of
two instructions (i.e. a vector load plus INSERTPSrr).
However, the existing target combine rule on INSERTPS nodes only works under
the assumption that ISel will always be able to match an INSERTPSrm. This is
not true in general at -O0, since the backend only allows folding a load into
the memory operand of an instruction if the optimization level is not
CodeGenOpt::None.
In the example below:
//
__m128 test(__m128 a, __m128 *b) {
__m128 c = _mm_insert_ps(a, *b, 1 << 6);
return c;
}
//
Before this patch, at -O0, the backend would have canonicalized the load to 'b'
into a scalar load plus scalar_to_vector. Later on, ISel would have selected an
INSERTPSrr leaving the insertps mask in an inconsistent state:
movss 4(%rdi), %xmm1
insertps $64, %xmm1, %xmm0 # xmm0 = xmm1[1],xmm0[1,2,3].
With this patch, the backend avoids folding the vector load into the operand of
the INSERTPS. The new codegen at -O0 is:
movaps (%rdi), %xmm1
insertps $64, %xmm1, %xmm0 # %xmm1[1],xmm0[1,2,3].
llvm-svn: 226277
If there is no associated immediate (MS style inline asm), do not try to access
the operand, assume that it is valid. This should fix the buildbots after SVN
r225941.
llvm-svn: 225950
The int instruction takes as an operand an 8-bit immediate value. Validate that
the input is valid rather than silently truncating the value.
llvm-svn: 225941
A pass that adds random noops to X86 binaries to introduce diversity with the goal of increasing security against most return-oriented programming attacks.
Command line options:
-noop-insertion // Enable noop insertion.
-noop-insertion-percentage=X // X% of assembly instructions will have a noop prepended (default: 50%, requires -noop-insertion)
-max-noops-per-instruction=X // Randomly generate X noops per instruction. ie. roll the dice X times with probability set above (default: 1). This doesn't guarantee X noop instructions.
In addition, the following 'quick switch' in clang enables basic diversity using default settings (currently: noop insertion and schedule randomization; it is intended to be extended in the future).
-fdiversify
This is the llvm part of the patch.
clang part: D3393
http://reviews.llvm.org/D3392
Patch by Stephen Crane (@rinon)
llvm-svn: 225908
This now handles both 32 and 64-bit element sizes.
In this version, the test are in vector-shuffle-512-v8.ll, canonicalized by
Chandler's update_llc_test_checks.py.
Part of <rdar://problem/17688758>
llvm-svn: 225838
This name is less descriptive, but it sort of puts things in the
'llvm.frame...' namespace, relating it to frameallocate and
frameaddress. It also avoids using "allocate" and "allocation" together.
llvm-svn: 225752
These intrinsics allow multiple functions to share a single stack
allocation from one function's call frame. The function with the
allocation may only perform one allocation, and it must be in the entry
block.
Functions accessing the allocation call llvm.recoverframeallocation with
the function whose frame they are accessing and a frame pointer from an
active call frame of that function.
These intrinsics are very difficult to inline correctly, so the
intention is that they be introduced rarely, or at least very late
during EH preparation.
Reviewers: echristo, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D6493
llvm-svn: 225746
r225551 vector byte shuffle optimization caused an assertion as fully zeroable vectors can be produced under certain circumstances. This fix drops the assert and returns a zero vector where the assert would have failed.
llvm-svn: 225718
This happens in the HINT benchmark, where the SLP-vectorizer created
v2f32 fcmp/select code. The "correct" solution would have been to
teach the vectorizer cost model that v2f32 isn't legal (because really,
it isn't), but if we can vectorize we might as well do so.
We legalize these v2f32 FMIN/FMAX nodes by widening to v4f32 later on.
v3f32 were already widened to v4f32 by the generic unroll-and-build-vector
legalization.
rdar://15763436
Differential Revision: http://reviews.llvm.org/D6557
llvm-svn: 225691
One is that AArch64 has additional restrictions on when local relocations can
be used. We have to take those into consideration when deciding to put a L
symbol in the symbol table or not.
The other is that ld64 requires the relocations to cstring to use linker
visible symbols on AArch64.
Thanks to Michael Zolotukhin for testing this!
Remove doesSectionRequireSymbols.
In an assembly expression like
bar:
.long L0 + 1
the intended semantics is that bar will contain a pointer one byte past L0.
In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.
The solution used in ELF to use relocation with symbols if there is a non-zero
addend.
In MachO before this patch we would just keep all symbols in some sections.
This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.
This patch implements the non-zero addend logic for MachO too.
llvm-svn: 225644
D6015 / rL221313 enabled commutation for SSE immediate blend instructions, but due to a typo the AVX2 VPBLENDW ymm instructions weren't flagged as commutative along with the others in the tables, but were still being commuted in code and tested for.
llvm-svn: 225612
It's possible for the constant pool entry for the shuffle mask to come
from a completely different operation. This occurs when Constants have
the same bit pattern but have different types.
Make DecodePSHUFBMask tolerant of types which, after a bitcast, are
appropriately sized vector types.
This fixes PR22188.
llvm-svn: 225597
Teach the ISelLowering for X86 about the L,M,O target specific constraints.
Although, for the moment, clang performs constraint validation and prevents
passing along inline asm which may have immediate constant constraints violated,
the backend should be able to cope with the invalid inline asm a bit better.
llvm-svn: 225596
In the current code we only attempt to match against insertps if we have exactly one element from the second input vector, irrespective of how much of the shuffle result is zeroable.
This patch checks to see if there is a single non-zeroable element from either input that requires insertion. It also supports matching of cases where only one of the inputs need to be referenced.
We also split insertps shuffle matching off into a new lowerVectorShuffleAsInsertPS function.
Differential Revision: http://reviews.llvm.org/D6879
llvm-svn: 225589
pshufb can shuffle in zero bytes as well as bytes from a source vector - we can use this to avoid having to shuffle 2 vectors and ORing the result when the used inputs from a vector are all zeroable.
Differential Revision: http://reviews.llvm.org/D6878
llvm-svn: 225551
complements the new vector shuffle lowering code path. This flag,
naturally, is *off* because we've not tested or evaluated the results of
this at all. However, the flag will make it much easier to evaluate
whether we can be this aggressive and whether there are missing vector
shuffle lowering optimizations.
llvm-svn: 225491
The call lowering assumes that if the callee is a global, we want to emit a direct call.
This is correct for regular globals, but not for TLS ones.
Differential Revision: http://reviews.llvm.org/D6862
llvm-svn: 225438
type (in addition to the memory type).
The *LoadExt* legalization handling used to only have one type, the
memory type. This forced users to assume that as long as the extload
for the memory type was declared legal, and the result type was legal,
the whole extload was legal.
However, this isn't always the case. For instance, on X86, with AVX,
this is legal:
v4i32 load, zext from v4i8
but this isn't:
v4i64 load, zext from v4i8
Whereas v4i64 is (arguably) legal, even without AVX2.
Note that the same thing was done a while ago for truncstores (r46140),
but I assume no one needed it yet for extloads, so here we go.
Calls to getLoadExtAction were changed to add the value type, found
manually in the surrounding code.
Calls to setLoadExtAction were mechanically changed, by wrapping the
call in a loop, to match previous behavior. The loop iterates over
the MVT subrange corresponding to the memory type (FP vectors, etc...).
I also pulled neighboring setTruncStoreActions into some of the loops;
those shouldn't make a difference, as the additional types are illegal.
(e.g., i128->i1 truncstores on PPC.)
No functional change intended.
Differential Revision: http://reviews.llvm.org/D6532
llvm-svn: 225421
LLVM emits stack probes on Windows targets to ensure that the stack is
correctly accessed. However, the amount of stack allocated before
emitting such a probe is hardcoded to 4096.
It is desirable to have this be configurable so that a function might
opt-out of stack probes. Our level of granularity is at the function
level instead of, say, the module level to permit proper generation of
code after LTO.
Patch by Andrew H!
N.B. The inliner needs to be updated to properly consider what happens
after inlining a function with a specific stack-probe-size into another
function with a different stack-probe-size.
llvm-svn: 225360
This is affecting the behavior of some ObjC++ / AArch64 test cases on Darwin.
Reverting to get the bots green while I track down the source of the changed
behavior.
llvm-svn: 225311
Requires new AsmParserOperand types that detect 16-bit and 32/64-bit mode so that we choose the right instruction based on default sizing without predicates. This is necessary since predicates mess up the disassembler table building.
llvm-svn: 225256
Overall this seems simpler. It reduces duplication of patterns between both modes and it simplifies the memory folding/unfolding tables as they don't need to create fake instructions just to keep track of 64-bitness.
llvm-svn: 225252
"ELF Handling for Thread-Local Storage" specifies that R_X86_64_GOTTPOFF
relocation target a movq or addq instruction.
Prohibit the truncation of such loads to movl or addl.
This fixes PR22083.
Differential Revision: http://reviews.llvm.org/D6839
llvm-svn: 225250
The assembler backend will relax to the long form if necessary. This removes a swap from long form to short form in the MCInstLowering code. Selecting the long form used to be required by the old JIT.
llvm-svn: 225242
Make sure they all have llvm_unreachable on the default path out of the switch. Remove unnecessary "default: break". Remove a 'return' after unreachable. Fix some indentation.
llvm-svn: 225114
This is necessary to allow the disassembler to be able to handle AdSize32 instructions in 64-bit mode when address size prefix is used.
Eventually we should probably also support 'addr32' and 'addr16' in the assembler to override the address size on some of these instructions. But for now we'll just use special operand types that will lookup the current mode size to select the right instruction.
llvm-svn: 225075
The issues was that AArch64 has additional restrictions on when local
relocations can be used. We have to take those into consideration when
deciding to put a L symbol in the symbol table or not.
Original message:
Remove doesSectionRequireSymbols.
In an assembly expression like
bar:
.long L0 + 1
the intended semantics is that bar will contain a pointer one byte past L0.
In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.
The solution used in ELF to use relocation with symbols if there is a non-zero
addend.
In MachO before this patch we would just keep all symbols in some sections.
This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.
This patch implements the non-zero addend logic for MachO too.
llvm-svn: 225048
Under the large code model, we cannot assume that __morestack lives within
2^31 bytes of the call site, so we cannot use pc-relative addressing. We
cannot perform the call via a temporary register, as the rax register may
be used to store the static chain, and all other suitable registers may be
either callee-save or used for parameter passing. We cannot use the stack
at this point either because __morestack manipulates the stack directly.
To avoid these issues, perform an indirect call via a read-only memory
location containing the address.
This solution is not perfect, as it assumes that the .rodata section
is laid out within 2^31 bytes of each function body, but this seems to
be sufficient for JIT.
Differential Revision: http://reviews.llvm.org/D6787
llvm-svn: 225003
In an assembly expression like
bar:
.long L0 + 1
the intended semantics is that bar will contain a pointer one byte past L0.
In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.
The solution used in ELF to use relocation with symbols if there is a non-zero
addend.
In MachO before this patch we would just keep all symbols in some sections.
This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.
This patch implements the non-zero addend logic for MachO too.
llvm-svn: 224985
The else case ResultReg was not checked for validity.
To my surprise, this case was not hit in any of the
existing test cases. This includes a new test cases
that tests this path.
Also drop the `target triple` declaration from the
original test as suggested by H.J. Lu, because
apparently with it the test won't be run on Linux
llvm-svn: 224901
If the control flow is modelling an if-statement where the only instruction in
the 'then' basic block (excluding the terminator) is a call to cttz/ctlz,
CodeGenPrepare can try to speculate the cttz/ctlz call and simplify the control
flow graph.
Example:
\code
entry:
%cmp = icmp eq i64 %val, 0
br i1 %cmp, label %end.bb, label %then.bb
then.bb:
%c = tail call i64 @llvm.cttz.i64(i64 %val, i1 true)
br label %end.bb
end.bb:
%cond = phi i64 [ %c, %then.bb ], [ 64, %entry]
\code
In this example, basic block %then.bb is taken if value %val is not zero.
Also, the phi node in %end.bb would propagate the size-of in bits of %val
only if %val is equal to zero.
With this patch, CodeGenPrepare will try to hoist the call to cttz from %then.bb
into basic block %entry only if cttz is cheap to speculate for the target.
Added two new hooks in TargetLowering.h to let targets customize the behavior
(i.e. decide whether it is cheap or not to speculate calls to cttz/ctlz). The
two new methods are 'isCheapToSpeculateCtlz' and 'isCheapToSpeculateCttz'.
By default, both methods return 'false'.
On X86, method 'isCheapToSpeculateCtlz' returns true only if the target has
LZCNT. Method 'isCheapToSpeculateCttz' only returns true if the target has BMI.
Differential Revision: http://reviews.llvm.org/D6728
llvm-svn: 224899
Summary:
Consider the following IR:
%3 = load i8* undef
%4 = trunc i8 %3 to i1
%5 = call %jl_value_t.0* @foo(..., i1 %4, ...)
ret %jl_value_t.0* %5
Bools (that are the result of direct truncs) are lowered as whatever
the argument to the trunc was and a "and 1", causing the part of the
MBB responsible for this argument to look something like this:
%vreg8<def,tied1> = AND8ri %vreg7<kill,tied0>, 1, %EFLAGS<imp-def>; GR8:%vreg8,%vreg7
Later, when the load is lowered, it will insert
%vreg15<def> = MOV8rm %vreg14, 1, %noreg, 0, %noreg; mem:LD1[undef] GR8:%vreg15 GR64:%vreg14
but remember to (at the end of isel) replace vreg7 by vreg15. Now for
the bug. In fast isel lowering, we mistakenly mark vreg8 as the result
of the load instead of the trunc. This adds a fixup to have
vreg8 replaced by whatever the result of the load is as well, so
we end up with
%vreg15<def,tied1> = AND8ri %vreg15<kill,tied0>, 1, %EFLAGS<imp-def>; GR8:%vreg15
which is an SSA violation and causes problems later down the road.
This fixes PR21557.
Test Plan: Test test case from PR21557 is added to the test suite.
Reviewers: ributzka
Reviewed By: ributzka
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D6245
llvm-svn: 224884
This removes a hardcoded list of instructions in the CodeEmitter. Eventually I intend to remove the predicates on the affected instructions since in any given mode two of them are valid if we supported addr32/addr16 prefixes in the assembler.
llvm-svn: 224809
When combining consecutive loads+inserts into a single vector load,
we should keep the alignment of the base load. Doing otherwise can, and does,
lead to using overly aligned instructions. In the included test case, for
example, using a 32-byte vmovaps on a 16-byte aligned value. Oops.
rdar://19190968
llvm-svn: 224746
Previously I tried to plug musttail into the existing vararg lowering
code. That turned out to be a mistake, because non-vararg calls use
significantly different register lowering, even on x86. For example, AVX
vectors are usually passed in registers to normal functions and memory
to vararg functions. Now musttail uses a completely separate lowering.
Hopefully this can be used as the basis for non-x86 perfect forwarding.
Reviewers: majnemer
Differential Revision: http://reviews.llvm.org/D6156
llvm-svn: 224745
Currently, when ctpop is supported for scalar types, the expansion of
@llvm.ctpop.vXiY uses vector element extractions, insertions and individual
calls to @llvm.ctpop.iY. When not, expansion with bit-math operations is used
for the scalar calls.
Local haswell measurements show that we can improve vector @llvm.ctpop.vXiY
expansion in some cases by using a using a vector parallel bit twiddling
approach, based on:
v = v - ((v >> 1) & 0x55555555);
v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
v = ((v + (v >> 4) & 0xF0F0F0F)
v = v + (v >> 8)
v = v + (v >> 16)
v = v & 0x0000003F
(from http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel)
When scalar ctpop isn't supported, the approach above performs better for
v2i64, v4i32, v4i64 and v8i32 (see numbers below). And even when scalar ctpop
is supported, this approach performs ~2x better for v8i32.
Here, x86_64 implies -march=corei7-avx without ctpop and x86_64h includes ctpop
support with -march=core-avx2.
== [x86_64h - new]
v8i32: 0.661685
v4i32: 0.514678
v4i64: 0.652009
v2i64: 0.324289
== [x86_64h - old]
v8i32: 1.29578
v4i32: 0.528807
v4i64: 0.65981
v2i64: 0.330707
== [x86_64 - new]
v8i32: 1.003
v4i32: 0.656273
v4i64: 1.11711
v2i64: 0.754064
== [x86_64 - old]
v8i32: 2.34886
v4i32: 1.72053
v4i64: 1.41086
v2i64: 1.0244
More work for other vector types will come next.
llvm-svn: 224725
It is intended to be used for a family of personality functions that
have similar IR preparation requirements. Typically when interoperating
with MSVC personality functions, bits of functionality need to be
outlined from the main function into helper functions. There is also
usually more than one landing pad per invoke, which does not match the
LLVM IR landingpad representation.
None of this is implemented yet. This change just adds a new enum that
is active for *-windows-msvc and delegates to the EH removal preparation
pass. No functionality change for other targets.
llvm-svn: 224625
Added RegOp2MemOpTable4 to transform 4th operand from register to memory in merge-masked versions of instructions.
Added lowering tests.
llvm-svn: 224516
Near as I can tell prefixes are ignored on these instructions except for a comment in the Intel docs about 0xf3. Binutils disassembler seems to ignore prefixes on these instructions. Our disassembler still doesn't distinguish PS and "no prefix" well enough for this to make a functional change, but it helps with experiments I'm doing on a potential new disassembler table builder.
llvm-svn: 224496
This handles the case of a BUILD_VECTOR being constructed out of elements extracted from a vector twice the size of the result vector. Previously this was always scalarized. Now, we try to construct a shuffle node that feeds on extract_subvectors.
This fixes PR15872 and provides a partial fix for PR21711.
Differential Revision: http://reviews.llvm.org/D6678
llvm-svn: 224429
The type promotion helper does not support vector type, so when make
such it does not kick in in such cases.
Original commit message:
[CodeGenPrepare] Move sign/zero extensions near loads using type promotion.
This patch extends the optimization in CodeGenPrepare that moves a sign/zero
extension near a load when the target can combine them. The optimization may
promote any operations between the extension and the load to make that possible.
Although this optimization may be beneficial for all targets, in particular
AArch64, this is enabled for X86 only as I have not benchmarked it for other
targets yet.
** Context **
Most targets feature extended loads, i.e., loads that perform a zero or sign
extension for free. In that context it is interesting to expose such pattern in
CodeGenPrepare so that the instruction selection pass can form such loads.
Sometimes, this pattern is blocked because of instructions between the load and
the extension. When those instructions are promotable to the extended type, we
can expose this pattern.
** Motivating Example **
Let us consider an example:
define void @foo(i8* %addr1, i32* %addr2, i8 %a, i32 %b) {
%ld = load i8* %addr1
%zextld = zext i8 %ld to i32
%ld2 = load i32* %addr2
%add = add nsw i32 %ld2, %zextld
%sextadd = sext i32 %add to i64
%zexta = zext i8 %a to i32
%addza = add nsw i32 %zexta, %zextld
%sextaddza = sext i32 %addza to i64
%addb = add nsw i32 %b, %zextld
%sextaddb = sext i32 %addb to i64
call void @dummy(i64 %sextadd, i64 %sextaddza, i64 %sextaddb)
ret void
}
As it is, this IR generates the following assembly on x86_64:
[...]
movzbl (%rdi), %eax # zero-extended load
movl (%rsi), %es # plain load
addl %eax, %esi # 32-bit add
movslq %esi, %rdi # sign extend the result of add
movzbl %dl, %edx # zero extend the first argument
addl %eax, %edx # 32-bit add
movslq %edx, %rsi # sign extend the result of add
addl %eax, %ecx # 32-bit add
movslq %ecx, %rdx # sign extend the result of add
[...]
The throughput of this sequence is 7.45 cycles on Ivy Bridge according to IACA.
Now, by promoting the additions to form more extended loads we would generate:
[...]
movzbl (%rdi), %eax # zero-extended load
movslq (%rsi), %rdi # sign-extended load
addq %rax, %rdi # 64-bit add
movzbl %dl, %esi # zero extend the first argument
addq %rax, %rsi # 64-bit add
movslq %ecx, %rdx # sign extend the second argument
addq %rax, %rdx # 64-bit add
[...]
The throughput of this sequence is 6.15 cycles on Ivy Bridge according to IACA.
This kind of sequences happen a lot on code using 32-bit indexes on 64-bit
architectures.
Note: The throughput numbers are similar on Sandy Bridge and Haswell.
** Proposed Solution **
To avoid the penalty of all these sign/zero extensions, we merge them in the
loads at the beginning of the chain of computation by promoting all the chain of
computation on the extended type. The promotion is done if and only if we do not
introduce new extensions, i.e., if we do not degrade the code quality.
To achieve this, we extend the existing “move ext to load” optimization with the
promotion mechanism introduced to match larger patterns for addressing mode
(r200947).
The idea of this extension is to perform the following transformation:
ext(promotableInst1(...(promotableInstN(load))))
=>
promotedInst1(...(promotedInstN(ext(load))))
The promotion mechanism in that optimization is enabled by a new TargetLowering
switch, which is off by default. In other words, by default, the optimization
performs the “move ext to load” optimization as it was before this patch.
** Performance **
Configuration: x86_64: Ivy Bridge fixed at 2900MHz running OS X 10.10.
Tested Optimization Levels: O3/Os
Tests: llvm-testsuite + externals.
Results:
- No regression beside noise.
- Improvements:
CINT2006/473.astar: ~2%
Benchmarks/PAQ8p: ~2%
Misc/perlin: ~3%
The results are consistent for both O3 and Os.
<rdar://problem/18310086>
llvm-svn: 224402
Added a missing memory folding relationship for the (V)CVTPD2PS instruction - we can safely fold these for stack reloads.
Differential Revision: http://reviews.llvm.org/D6663
llvm-svn: 224383
Summary: As a side-quest for D6629 jvoung pointed out that I should use -verify-machineinstrs and this found a bug in x86-32's handling of EFLAGS for PUSHF/POPF. This patch fixes the use/def, and adds -verify-machineinstrs to all x86 tests which contain 'EFLAGS'. One exception: this patch leaves inline-asm-fpstack.ll as-is because it fails -verify-machineinstrs in a way unrelated to EFLAGS. This patch also modifies cmpxchg-clobber-flags.ll along the lines of what D6629 already does by also testing i386.
Test Plan: ninja check
Reviewers: t.p.northover, jvoung
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D6687
llvm-svn: 224359
This patch extends the optimization in CodeGenPrepare that moves a sign/zero
extension near a load when the target can combine them. The optimization may
promote any operations between the extension and the load to make that possible.
Although this optimization may be beneficial for all targets, in particular
AArch64, this is enabled for X86 only as I have not benchmarked it for other
targets yet.
** Context **
Most targets feature extended loads, i.e., loads that perform a zero or sign
extension for free. In that context it is interesting to expose such pattern in
CodeGenPrepare so that the instruction selection pass can form such loads.
Sometimes, this pattern is blocked because of instructions between the load and
the extension. When those instructions are promotable to the extended type, we
can expose this pattern.
** Motivating Example **
Let us consider an example:
define void @foo(i8* %addr1, i32* %addr2, i8 %a, i32 %b) {
%ld = load i8* %addr1
%zextld = zext i8 %ld to i32
%ld2 = load i32* %addr2
%add = add nsw i32 %ld2, %zextld
%sextadd = sext i32 %add to i64
%zexta = zext i8 %a to i32
%addza = add nsw i32 %zexta, %zextld
%sextaddza = sext i32 %addza to i64
%addb = add nsw i32 %b, %zextld
%sextaddb = sext i32 %addb to i64
call void @dummy(i64 %sextadd, i64 %sextaddza, i64 %sextaddb)
ret void
}
As it is, this IR generates the following assembly on x86_64:
[...]
movzbl (%rdi), %eax # zero-extended load
movl (%rsi), %es # plain load
addl %eax, %esi # 32-bit add
movslq %esi, %rdi # sign extend the result of add
movzbl %dl, %edx # zero extend the first argument
addl %eax, %edx # 32-bit add
movslq %edx, %rsi # sign extend the result of add
addl %eax, %ecx # 32-bit add
movslq %ecx, %rdx # sign extend the result of add
[...]
The throughput of this sequence is 7.45 cycles on Ivy Bridge according to IACA.
Now, by promoting the additions to form more extended loads we would generate:
[...]
movzbl (%rdi), %eax # zero-extended load
movslq (%rsi), %rdi # sign-extended load
addq %rax, %rdi # 64-bit add
movzbl %dl, %esi # zero extend the first argument
addq %rax, %rsi # 64-bit add
movslq %ecx, %rdx # sign extend the second argument
addq %rax, %rdx # 64-bit add
[...]
The throughput of this sequence is 6.15 cycles on Ivy Bridge according to IACA.
This kind of sequences happen a lot on code using 32-bit indexes on 64-bit
architectures.
Note: The throughput numbers are similar on Sandy Bridge and Haswell.
** Proposed Solution **
To avoid the penalty of all these sign/zero extensions, we merge them in the
loads at the beginning of the chain of computation by promoting all the chain of
computation on the extended type. The promotion is done if and only if we do not
introduce new extensions, i.e., if we do not degrade the code quality.
To achieve this, we extend the existing “move ext to load” optimization with the
promotion mechanism introduced to match larger patterns for addressing mode
(r200947).
The idea of this extension is to perform the following transformation:
ext(promotableInst1(...(promotableInstN(load))))
=>
promotedInst1(...(promotedInstN(ext(load))))
The promotion mechanism in that optimization is enabled by a new TargetLowering
switch, which is off by default. In other words, by default, the optimization
performs the “move ext to load” optimization as it was before this patch.
** Performance **
Configuration: x86_64: Ivy Bridge fixed at 2900MHz running OS X 10.10.
Tested Optimization Levels: O3/Os
Tests: llvm-testsuite + externals.
Results:
- No regression beside noise.
- Improvements:
CINT2006/473.astar: ~2%
Benchmarks/PAQ8p: ~2%
Misc/perlin: ~3%
The results are consistent for both O3 and Os.
<rdar://problem/18310086>
llvm-svn: 224351
This is a fix for PR21709 ( http://llvm.org/bugs/show_bug.cgi?id=21709 ).
When we have 2 consecutive 16-byte loads that are merged into one 32-byte vector,
we can use a single 32-byte load instead.
But we don't do this for SandyBridge / IvyBridge because they have slower 32-byte memops.
We also don't bother using 32-byte *integer* loads on a machine that only has AVX1 (btver2)
because those operands would have to be split in half anyway since there is no support for
32-byte integer math ops.
Differential Revision: http://reviews.llvm.org/D6492
llvm-svn: 224344
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
Summary: x86 allows either ordering for the LOCK and DATA16 prefixes, but using GCC+GAS leads to different code generation than using LLVM. This change matches the order that GAS emits the x86 prefixes when a semicolon isn't used in inline assembly (see tc-i386.c comment before define LOCK_PREFIX), and helps simplify tooling that operates on the instruction's byte sequence (such as NaCl's validator). This change shouldn't have any performance impact.
Test Plan: ninja check
Reviewers: craig.topper, jvoung
Subscribers: jfb, llvm-commits
Differential Revision: http://reviews.llvm.org/D6630
llvm-svn: 224283
Adds the various "rm" instruction variants into the list of instructions that have a partial register update. Also adds all variants of SQRTSD that were missing in the original list.
Differential Revision: http://reviews.llvm.org/D6620
llvm-svn: 224246
Previously print+verify passes were added in a very unsystematic way, which is
annoying when debugging as you miss intermediate steps and allows bugs to stay
unnotice when no verification is performed.
To make this change practical I added the possibility to explicitely disable
verification. I used this option on all places where no verification was
performed previously (because alot of places actually don't pass the
MachineVerifier).
In the long term these problems should be fixed properly and verification
enabled after each pass. I'll enable some more verification in subsequent
commits.
This is the 2nd attempt at this after realizing that PassManager::add() may
actually delete the pass.
llvm-svn: 224059
Previously print+verify passes were added in a very unsystematic way, which is
annoying when debugging as you miss intermediate steps and allows bugs to stay
unnotice when no verification is performed.
To make this change practical I added the possibility to explicitely disable
verification. I used this option on all places where no verification was
performed previously (because alot of places actually don't pass the
MachineVerifier).
In the long term these problems should be fixed properly and verification
enabled after each pass. I'll enable some more verification in subsequent
commits.
llvm-svn: 224042
Add patterns to match SSE (shufpd) and AVX (vpermilpd) shuffle codegen
when storing the high element of a v2f64. The existing patterns were
only checking for an unpckh type of shuffle.
http://llvm.org/bugs/show_bug.cgi?id=21791
Differential Revision: http://reviews.llvm.org/D6586
llvm-svn: 223929
EltsFromConsecutiveLoads was apparently only ever called for 128-bit vectors, and assumed this implicitly. r223518 started calling it for AVX-sized vectors, causing the code path that had this assumption to crash.
This adds a check to make this path fire only for 128-bit vectors.
Differential Revision: http://reviews.llvm.org/D6579
llvm-svn: 223922
Lowering patterns were written through avx512_broadcast_pat multiclass as pattern generates VBROADCAST and COPY_TO_REGCLASS nodes.
Added lowering tests.
llvm-svn: 223804
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
This handles the simplest case for mov -> push conversion:
1. x86-32 calling convention, everything is passed through the stack.
2. There is no reserved call frame.
3. Only registers or immediates are pushed, no attempt to combine a mem-reg-mem sequence into a single PUSHmm.
Differential Revision: http://reviews.llvm.org/D6503
llvm-svn: 223757
Fix a compact unwind encoding logic bug which would try to encode
more callee saved registers than it should, leading to early bail out
in the encoding logic and abusive use of DWARF frame mode unnecessarily.
Also remove no-compact-unwind.ll which was testing the wrong thing
based on this bug and move it to valid 'compact unwind' tests. Added
other few more tests too.
llvm-svn: 223676
Teach ISel how to match a TZCNT/LZCNT from a conditional move if the
condition code is X86_COND_NE.
Existing tablegen patterns only allowed to match TZCNT/LZCNT from a
X86cond with condition code equal to X86_COND_E. To avoid introducing
extra rules, I added an 'ImmLeaf' definition that checks if the
condition code is COND_E or COND_NE.
llvm-svn: 223668
Before this patch, the backend sub-optimally expanded the non-constant shift
count of a v8i16 shift into a sequence of two 'movd' plus 'movzwl'.
With this patch the backend checks if the target features sse4.1. If so, then
it lets the shuffle legalizer deal with the expansion of the shift amount.
Example:
;;
define <8 x i16> @test(<8 x i16> %A, <8 x i16> %B) {
%shamt = shufflevector <8 x i16> %B, <8 x i16> undef, <8 x i32> zeroinitializer
%shl = shl <8 x i16> %A, %shamt
ret <8 x i16> %shl
}
;;
Before (with -mattr=+avx):
vmovd %xmm1, %eax
movzwl %ax, %eax
vmovd %eax, %xmm1
vpsllw %xmm1, %xmm0, %xmm0
retq
Now:
vpxor %xmm2, %xmm2, %xmm2
vpblendw $1, %xmm1, %xmm2, %xmm1
vpsllw %xmm1, %xmm0, %xmm0
retq
llvm-svn: 223660
X86ISelLowering.cpp has a long switch for intrinsics. I moved a part of
this long switch to the new intrinsics table in X86IntrinsicsInfo.h.
No functional changes, just code and compile time optimization.
llvm-svn: 223641
Andrea Di Biagio