In particular, this preserves the kill flag, which allows the Thumb2 cbn?z
optimization to be applied in cases where a branch has been re-created after
the live variables analysis pass, e.g. by the machine block placement pass.
This appears to be low risk; a number of other targets seem to already be
doing something similar, e.g. AArch64, PowerPC.
Differential Revision: http://reviews.llvm.org/D9184
llvm-svn: 235639
This allows the constant island pass to lower these branches to cbn?z
instructions, resulting in a shorter instruction sequence.
Differential Revision: http://reviews.llvm.org/D9183
llvm-svn: 235638
This makes it more likely that we can use the 16-bit push and pop instructions
on Thumb-2, saving around 4 bytes per function.
Differential Revision: http://reviews.llvm.org/D9165
llvm-svn: 235637
This appears to have been introduced back in r76698 as part of an unrelated
change. I can find no official ARM documentation stating that Thumb-2 functions
require 4-byte alignment; in fact, ARM documentation appears to contradict
this (see, e.g., ARM Architecture Reference Manual Thumb-2 Supplement,
section 2.6.1: "Thumb-2 enforces 16-bit alignment on all instructions.").
Also remove code that sets alignment for ARM functions, which is redundant
with code in the MachineFunction constructor, and remove the hidden
-arm-align-constant-islands flag, which has been enabled by default since
r146739 (Dec 2011) and has probably received sufficient testing by now.
Differential Revision: http://reviews.llvm.org/D9138
llvm-svn: 235636
Specifically, if a pointer accesses different underlying objects in each
iteration, don't look through the phi node defining the pointer.
The motivating case is the underlyling-objects-2.ll testcase. Consider
the loop nest:
int **A;
for (i)
for (j)
A[i][j] = A[i-1][j] * B[j]
This loop is transformed by Load-PRE to stash away A[i] for the next
iteration of the outer loop:
Curr = A[0]; // Prev_0
for (i: 1..N) {
Prev = Curr; // Prev = PHI (Prev_0, Curr)
Curr = A[i];
for (j: 0..N)
Curr[j] = Prev[j] * B[j]
}
Since A[i] and A[i-1] are likely to be independent pointers,
getUnderlyingObjects should not assume that Curr and Prev share the same
underlying object in the inner loop.
If it did we would try to dependence-analyze Curr and Prev and the
analysis of the corresponding SCEVs would fail with non-constant
distance.
To fix this, the getUnderlyingObjects API is extended with an optional
LoopInfo parameter. This is effectively what controls whether we want
the above behavior or the original. Currently, I only changed to use
this approach for LoopAccessAnalysis.
The other testcase is to guard the opposite case where we do want to
look through the loop PHI. If we step through an array by incrementing
a pointer, the underlying object is the incoming value of the phi as the
loop is entered.
Fixes rdar://problem/19566729
llvm-svn: 235634
Summary:
We pick this order because SeparateConstOffsetFromGEP may create more
opportunities for SLSR.
Test Plan:
reassociate-geps-and-slsr.ll
no performance regression on internal benchmarks
Reviewers: meheff
Subscribers: llvm-commits, jholewinski
Differential Revision: http://reviews.llvm.org/D9230
llvm-svn: 235632
TableGen had been nicely generating code to print a number of instructions using
shorter aliases (and PowerPC has plenty of short mnemonics), but we were not
calling it. For some of the aliases we support in the parser, TableGen can't
infer the "inverse" alias relationship, so there is still more to do.
Thus, after some hours of updating test cases...
llvm-svn: 235616
Summary:
Constant stores of f16 vectors can create NvCast nodes from various
operand types to v4f16 or v8f16 depending on patterns in the stored
constants. This patch adds nvcast rules with v4f16 and v8f16 values.
AArchISelLowering::LowerBUILD_VECTOR has the details on which constant
patterns generate the nvcast nodes.
Reviewers: jmolloy, srhines, ab
Subscribers: rengolin, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D9201
llvm-svn: 235610
Summary:
Set operation action for SINT_TO_FP and UINT_TO_FP nodes with v4i32,
v8i8, v8i16 inputs to allow promotion of v4f16 results.
Add tests for sitofp and uitofp for vec4, vec8, vec16, and i8, i16, i32,
and i64 vectors. Only missing tests are for v16i8 and v16i16 as the
shift operations are too complicated to write a proper check sequence.
The conversions from v4i64 to v4f16 do not depend on this patch - v4i64
is split and the conversion gets handled while lowering v2i64. I am
adding a test here for completeness.
Reviewers: aemerson, rengolin, ab, jmolloy, srhines
Subscribers: rengolin, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D9166
llvm-svn: 235609
Third time's the charm. The previous commit was reverted as a
reverse for-loop in SelectionDAGBuilder::lowerWorkItem did 'I--'
on an iterator at the beginning of a vector, causing asserts
when using debugging iterators. This commit fixes that.
llvm-svn: 235608
Summary:
Make sure the abbrev operands are valid and that we can read/skip them
afterwards.
Bug found with AFL fuzz.
Reviewers: rafael
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9030
llvm-svn: 235595
Patch to remove extra bitcasts from shuffles, this is often a legacy of XformToShuffleWithZero being used to combine bitmaskings (of float vectors bitcast to integer vectors) into shuffles: bitcast(shuffle(bitcast(s0),bitcast(s1))) -> shuffle(s0,s1)
Differential Revision: http://reviews.llvm.org/D9097
llvm-svn: 235578
This is a re-commit of r235101, which also fixes the problems with the previous patch:
- Switches with only a default case and non-fallthrough were handled incorrectly
- The previous patch tickled a bug in PowerPC Early-Return Creation which is fixed here.
> This is a major rewrite of the SelectionDAG switch lowering. The previous code
> would lower switches as a binary tre, discovering clusters of cases
> suitable for lowering by jump tables or bit tests as it went along. To increase
> the likelihood of finding jump tables, the binary tree pivot was selected to
> maximize case density on both sides of the pivot.
>
> By not selecting the pivot in the middle, the binary trees would not always
> be balanced, leading to performance problems in the generated code.
>
> This patch rewrites the lowering to search for clusters of cases
> suitable for jump tables or bit tests first, and then builds the binary
> tree around those clusters. This way, the binary tree will always be balanced.
>
> This has the added benefit of decoupling the different aspects of the lowering:
> tree building and jump table or bit tests finding are now easier to tweak
> separately.
>
> For example, this will enable us to balance the tree based on profile info
> in the future.
>
> The algorithm for finding jump tables is quadratic, whereas the previous algorithm
> was O(n log n) for common cases, and quadratic only in the worst-case. This
> doesn't seem to be major problem in practice, e.g. compiling a file consisting
> of a 10k-case switch was only 30% slower, and such large switches should be rare
> in practice. Compiling e.g. gcc.c showed no compile-time difference. If this
> does turn out to be a problem, we could limit the search space of the algorithm.
>
> This commit also disables all optimizations during switch lowering in -O0.
>
> Differential Revision: http://reviews.llvm.org/D8649
llvm-svn: 235560
Only clear out the NSW/NUW flags if we are optimizing 'add'/'sub' while
taking advantage that the sign bit is not set. We do this optimization
to further shrink the mask but shrinking the mask isn't NSW/NUW
preserving in this case.
llvm-svn: 235558
This removes the -sehprepare flag and makes __C_specific_handler
functions always to use WinEHPrepare.
This was tested by building all of chromium_builder_tests and running a
few tests that use SEH, but if something breaks, we can revert this.
llvm-svn: 235557
In particular, this handles SSA values that are live *out* of a handler.
The existing code only handles values that are live *in* to a handler.
It also handles phi nodes in the block where normal control should
resume after the end of a catch handler. When EH return points have phi
nodes, we need to split the return edge. It is impossible for phi
elimination to emit copies in the previous block if that block gets
outlined. The indirectbr that we leave in the function is only notional,
and is eliminated from the MachineFunction CFG early on.
Reviewers: majnemer, andrew.w.kaylor
Differential Revision: http://reviews.llvm.org/D9158
llvm-svn: 235545
An nsw/nuw operation relies on the values feeding into it to not
overflow if 'poison' is not to be produced. This means that
optimizations which make modifications to the bottom of a chain (like
SimplifyDemandedBits) must strip out nsw/nuw if they cannot ensure that
they will be preserved.
This fixes PR23309.
llvm-svn: 235544
Summary:
Remove the CHECK-DAG calls introduced in r235341, and add a comment that
this test may break due to scheduling variations.
This patch completes the fix discussed in http://reviews.llvm.org/D8804
Reviewers: dsanders, srhines
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9178
llvm-svn: 235530
ARM32 ELF R_ARM_V4BX relocation format is a special relocation type
that records the location of an ARMv4t BX instruction to enable a
static linker to generate ARMv4 compatible instructions. This
relocation does not contain a reference symbol.
This patch enabled its creation by removing the requeriment of a
relocation symbol target in ELFState<ELFT>::writeSectionContent.
llvm-svn: 235513
An assert was triggered when attempting to create a new SCEV
with operands of different types in the visitAddRecExpr. In this
test case, the operand types of the numerator and denominator
are different. The SCEV division code should generate a
conservative answer when this happens.
Differential Revision: http://reviews.llvm.org/D9021
llvm-svn: 235511
This fixes a regression introduced at revision 218263.
On AVX, if we optimize for size, a splat build_vector of a load
is lowered into a VBROADCAST node. This is done even if the value type of the
splat build_vector node is v2i64.
Since AVX doesn't support v2f64/v2i64 broadcasts, revision 218263 added two
extra tablegen patterns to allow selecting a VMOVDDUPrm from an X86VBroadcast
where the scalar element comes from a loadi64/loadf64.
However, revision 218263 forgot to add an extra fallback pattern for the case
where we have a X86VBroadcast of a loadi64 with multiple uses.
This patch adds the missing tablegen pattern in X86InstrSSE.td.
This patch also adds an extra test to 'splat-for-size.ll' to verify that ISel
doesn't crash with a 'fatal error in the backend' due to a missing AVX pattern
to select v2i64 X86ISD::BROADCAST nodes.
llvm-svn: 235509
This turned up after r235333, but was a pre-existing bug. The optimization
which transforms select(c, load, load) into a load of a select of the addresses
does not handle indexed loads (pre/post inc/dec). However, it did not check for
them either, leading to a crash if it tried to transform one of them.
llvm-svn: 235497
Enough concerns were raised that this optimization is pessimising some code patterns.
The obvious fix, to add a Reassociate run afterwards, causes even more pessimisation in some cases due to fewer complex addressing modes being matched. As there isn't a trivial fix for this, backing this out by default until someone gets a chance to fix the addressing mode matcher.
llvm-svn: 235491
X86 backend.
The code generated for symbolic targets is identical to the code generated for
constant targets, except that a relocation is emitted to fix up the actual
target address at link-time. This allows IR and object files containing
patchpoints to be cached across JIT-invocations where the target address may
change.
llvm-svn: 235483
Add a flag to lib/Linker (and `llvm-link`) to override linkage rules.
When set, the functions in the source module *always* replace those in
the destination module.
The `llvm-link` option is `-override=abc.ll`. All the "regular" modules
are loaded and linked first, followed by the `-override` modules. This
is useful for debugging workflows where some subset of the module (e.g.,
a single function) is extracted into a separate file where it's
optimized differently, before being merged back in.
Patch by Luqman Aden!
llvm-svn: 235473
With SSE2, we can generate a 'movq' or other 64-bit store op on a 32-bit system
even though 64-bit integers are not legal types.
So instead of producing this:
pshufd $229, %xmm0, %xmm1 ## xmm1 = xmm0[1,1,2,3]
movd %xmm0, (%eax)
movd %xmm1, 4(%eax)
We can do:
movq %xmm0, (%eax)
This is a fix for the problem noted in D7296.
Differential Revision: http://reviews.llvm.org/D9134
llvm-svn: 235460
We should also teach the inliner to collapse framerecover of
frameaddress of the current frame down to an alloca, but that can happen
later.
llvm-svn: 235459
https://llvm.org/bugs/show_bug.cgi?id=23163.
Gep merging sometimes behaves like a reverse CSE/LICM optimization,
which has negative impact on performance. In this patch we restrict
gep merging to happen only when the indexes to be merged are both consts,
which ensures such merge is always beneficial.
The patch makes gep merging only happen in very restrictive cases.
It is possible that some analysis/optimization passes rely on the merged
geps to get better result, and we havn't notice them yet. We will be ready
to further improve it once we see the cases.
Differential Revision: http://reviews.llvm.org/D8911
llvm-svn: 235455
https://llvm.org/bugs/show_bug.cgi?id=23163.
Gep merging sometimes behaves like a reverse CSE/LICM optimizations,
which has negative impact on performance. In this patch we restrict
gep merging to happen only when the indexes to be merged are both consts,
which ensures such merge is always beneficial.
The patch makes gep merging only happen in very restrictive cases.
It is possible that some analysis/optimization passes rely on the merged
geps to get better result, and we havn't notice them yet. We will be ready
to further improve it once we see the cases.
Differential Revision: http://reviews.llvm.org/D9007
llvm-svn: 235451
