Now that MachineBasicBlock::reverse_instr_iterator knows when it's at
the end (since r281168 and r281170), implement
MachineBasicBlock::reverse_iterator directly on top of an
ilist::reverse_iterator by adding an IsReverse template parameter to
MachineInstrBundleIterator. This replaces another hard-to-reason-about
use of std::reverse_iterator on list iterators, matching the changes for
ilist::reverse_iterator from r280032 (see the "out of scope" section at
the end of that commit message). MachineBasicBlock::reverse_iterator
now has a handle to the current node and has obvious invalidation
semantics.
r280032 has a more detailed explanation of how list-style reverse
iterators (invalidated when the pointed-at node is deleted) are
different from vector-style reverse iterators like std::reverse_iterator
(invalidated on every operation). A great motivating example is this
commit's changes to lib/CodeGen/DeadMachineInstructionElim.cpp.
Note: If your out-of-tree backend deletes instructions while iterating
on a MachineBasicBlock::reverse_iterator or converts between
MachineBasicBlock::iterator and MachineBasicBlock::reverse_iterator,
you'll need to update your code in similar ways to r280032. The
following table might help:
[Old] ==> [New]
delete &*RI, RE = end() delete &*RI++
RI->erase(), RE = end() RI++->erase()
reverse_iterator(I) std::prev(I).getReverse()
reverse_iterator(I) ++I.getReverse()
--reverse_iterator(I) I.getReverse()
reverse_iterator(std::next(I)) I.getReverse()
RI.base() std::prev(RI).getReverse()
RI.base() ++RI.getReverse()
--RI.base() RI.getReverse()
std::next(RI).base() RI.getReverse()
(For more details, have a look at r280032.)
llvm-svn: 281172
Summary:
An IR load can be invariant, dereferenceable, neither, or both. But
currently, MI's notion of invariance is IR-invariant &&
IR-dereferenceable.
This patch splits up the notions of invariance and dereferenceability at
the MI level. It's NFC, so adds some probably-unnecessary
"is-dereferenceable" checks, which we can remove later if desired.
Reviewers: chandlerc, tstellarAMD
Subscribers: jholewinski, arsenm, nemanjai, llvm-commits
Differential Revision: https://reviews.llvm.org/D23371
llvm-svn: 281151
Summary:
I want to separate out the notions of invariance and dereferenceability
at the MI level, so that they correspond to the equivalent concepts at
the IR level. (Currently an MI load is MI-invariant iff it's
IR-invariant and IR-dereferenceable.)
First step is renaming this function.
Reviewers: chandlerc
Subscribers: MatzeB, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D23370
llvm-svn: 281125
This extends the optimization in r280832 to also work for 64-bit. The only
quirk is that we can't do this for 64-bit Windows (yet).
Differential Revision: https://reviews.llvm.org/D24423
llvm-svn: 281113
The x64 ABI has two major function types:
- frame functions
- leaf functions
A frame function is one which requires a stack frame. A leaf function
is one which does not. A frame function may or may not have a frame
pointer.
A leaf function does not require a stack frame and may never modify SP
except via a return (RET, tail call via JMP).
A frame function which has a frame pointer is permitted to use the LEA
instruction in the epilogue, a frame function without which doesn't
establish a frame pointer must use ADD to adjust the stack pointer epilogue.
Fun fact: Leaf functions don't require a function table entry
(associated PDATA/XDATA).
llvm-svn: 281006
The REX prefix should be used on indirect jmps, but not direct ones.
For direct jumps, the unwinder looks at the offset to determine if
it's inside the current function.
Differential Revision: https://reviews.llvm.org/D24359
llvm-svn: 281003
And associated commits, as they broke the Thumb bots.
This reverts commit r280935.
This reverts commit r280891.
This reverts commit r280888.
llvm-svn: 280967
This is a port of XRay to ARM 32-bit, without Thumb support yet. The XRay instrumentation support is moving up to AsmPrinter.
This is one of 3 commits to different repositories of XRay ARM port. The other 2 are:
1. https://reviews.llvm.org/D23932 (Clang test)
2. https://reviews.llvm.org/D23933 (compiler-rt)
Differential Revision: https://reviews.llvm.org/D23931
llvm-svn: 280888
The patch is to fix PR30298, which is caused by rL272694. The solution is to
bail out if the target has no SSE2.
Differential Revision: https://reviews.llvm.org/D24288
llvm-svn: 280837
When branching to a block that immediately tail calls, it is possible to fold
the call directly into the branch if the call is direct and there is no stack
adjustment, saving one byte.
Example:
define void @f(i32 %x, i32 %y) {
entry:
%p = icmp eq i32 %x, %y
br i1 %p, label %bb1, label %bb2
bb1:
tail call void @foo()
ret void
bb2:
tail call void @bar()
ret void
}
before:
f:
movl 4(%esp), %eax
cmpl 8(%esp), %eax
jne .LBB0_2
jmp foo
.LBB0_2:
jmp bar
after:
f:
movl 4(%esp), %eax
cmpl 8(%esp), %eax
jne bar
.LBB0_1:
jmp foo
I don't expect any significant size savings from this (on a Clang bootstrap I
saw 288 bytes), but it does make the code a little tighter.
This patch only does 32-bit, but 64-bit would work similarly.
Differential Revision: https://reviews.llvm.org/D24108
llvm-svn: 280832
The previous commit (r280368 - https://reviews.llvm.org/D23313) does not cover AVX-512F, KNL set.
FNEG(x) operation is lowered to (bitcast (vpxor (bitcast x), (bitcast constfp(0x80000000))).
It happens because FP XOR is not supported for 512-bit data types on KNL and we use integer XOR instead.
I added pattern match for integer XOR.
Differential Revision: https://reviews.llvm.org/D24221
llvm-svn: 280785
We need to bitcast the index operand to a floating point type so that it matches the result type. If not then the passthru part of the DAG will be a bitcast from the index's original type to the destination type. This makes it very difficult to match. The other option would be to add 5 sets of patterns for every other possible type.
llvm-svn: 280696
The code is now written in terms of source and dest classes with feature checks inside each type of copy instead of having separate functions for each feature set.
llvm-svn: 280673
Previously we were extending to copying the whole ZMM register. The register allocator shouldn't use XMM16-31 or YMM16-31 in this configuration as the instructions to spill them aren't available.
llvm-svn: 280648
The only way to select them was in AVX512 mode because EVEX VMOVSS/SD was below them and the patterns weren't qualified properly for AVX only. So if you happened to have an aligned FR32/FR64 load in AVX512 you could get a VEX encoded VMOVAPS/VMOVAPD.
I tried to search back through history and it seems like these instructions were probably unselectable for at least 5 years, at least to the time the VEX versions were added. But I can't prove they ever were.
llvm-svn: 280644
For the store of a wide value merged from a pair of values, especially int-fp pair,
sometimes it is more efficent to split it into separate narrow stores, which can
remove the bitwise instructions or sink them to colder places.
Now the feature is only enabled on x86 target, and only store of int-fp pair is
splitted. It is possible that the application scope gets extended with perf evidence
support in the future.
Differential Revision: https://reviews.llvm.org/D22840
llvm-svn: 280505
Prior to this, we could generate a vector_shuffle from an IR shuffle when the
size of the result was exactly the sum of the sizes of the input vectors.
If the output vector was narrower - e.g. a <12 x i8> being formed by a shuffle
with two <8 x i8> inputs - we would lower the shuffle to a sequence of extracts
and inserts.
Instead, we can form a larger vector_shuffle, and then extract a subvector
of the right size - e.g. shuffle the two <8 x i8> inputs into a <16 x i8>
and then extract a <12 x i8>.
This also includes a target-specific X86 combine that in the presence of
AVX2 combines:
(vector_shuffle <mask> (concat_vectors t1, undef)
(concat_vectors t2, undef))
into:
(vector_shuffle <mask> (concat_vectors t1, t2), undef)
in cases where this allows us to form VPERMD/VPERMQ.
(This is not a separate commit, as that pattern does not appear without
the DAGBuilder change.)
llvm-svn: 280418
According to spec cvtdq2pd and cvtps2pd instructions don't require memory operand to be aligned
to 16 bytes. This patch removes this requirement from the memory folding table.
Differential Revision: https://reviews.llvm.org/D23919
llvm-svn: 280402
Summary:
This change promotes the 'isTailCall(...)' member function to
TargetInstrInfo as a query interface for determining on a per-target
basis whether a given MachineInstr is a tail call instruction. We build
upon this in the XRay instrumentation pass to emit special sleds for
tail call optimisations, where we emit the correct kind of sled.
The tail call sleds look like a mix between the function entry and
function exit sleds. Form-wise, the sled comes before the "jmp"
instruction that implements the tail call similar to how we do it for
the function entry sled. Functionally, because we know this is a tail
call, it behaves much like an exit sled -- i.e. at runtime we may use
the exit trampolines instead of a different kind of trampoline.
A follow-up change to recognise these sleds will be done in compiler-rt,
so that we can start intercepting these initially as exits, but also
have the option to have different log entries to more accurately reflect
that this is actually a tail call.
Reviewers: echristo, rSerge, majnemer
Subscribers: mehdi_amini, dberris, llvm-commits
Differential Revision: https://reviews.llvm.org/D23986
llvm-svn: 280334
Duncan P. N. Exon Smith