This patch introduces a new pass that computes the safe point to insert the
prologue and epilogue of the function.
The interest is to find safe points that are cheaper than the entry and exits
blocks.
As an example and to avoid regressions to be introduce, this patch also
implements the required bits to enable the shrink-wrapping pass for AArch64.
** Context **
Currently we insert the prologue and epilogue of the method/function in the
entry and exits blocks. Although this is correct, we can do a better job when
those are not immediately required and insert them at less frequently executed
places.
The job of the shrink-wrapping pass is to identify such places.
** Motivating example **
Let us consider the following function that perform a call only in one branch of
a if:
define i32 @f(i32 %a, i32 %b) {
%tmp = alloca i32, align 4
%tmp2 = icmp slt i32 %a, %b
br i1 %tmp2, label %true, label %false
true:
store i32 %a, i32* %tmp, align 4
%tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
br label %false
false:
%tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
ret i32 %tmp.0
}
On AArch64 this code generates (removing the cfi directives to ease
readabilities):
_f: ; @f
; BB#0:
stp x29, x30, [sp, #-16]!
mov x29, sp
sub sp, sp, #16 ; =16
cmp w0, w1
b.ge LBB0_2
; BB#1: ; %true
stur w0, [x29, #-4]
sub x1, x29, #4 ; =4
mov w0, wzr
bl _doSomething
LBB0_2: ; %false
mov sp, x29
ldp x29, x30, [sp], #16
ret
With shrink-wrapping we could generate:
_f: ; @f
; BB#0:
cmp w0, w1
b.ge LBB0_2
; BB#1: ; %true
stp x29, x30, [sp, #-16]!
mov x29, sp
sub sp, sp, #16 ; =16
stur w0, [x29, #-4]
sub x1, x29, #4 ; =4
mov w0, wzr
bl _doSomething
add sp, x29, #16 ; =16
ldp x29, x30, [sp], #16
LBB0_2: ; %false
ret
Therefore, we would pay the overhead of setting up/destroying the frame only if
we actually do the call.
** Proposed Solution **
This patch introduces a new machine pass that perform the shrink-wrapping
analysis (See the comments at the beginning of ShrinkWrap.cpp for more details).
It then stores the safe save and restore point into the MachineFrameInfo
attached to the MachineFunction.
This information is then used by the PrologEpilogInserter (PEI) to place the
related code at the right place. This pass runs right before the PEI.
Unlike the original paper of Chow from PLDI’88, this implementation of
shrink-wrapping does not use expensive data-flow analysis and does not need hack
to properly avoid frequently executed point. Instead, it relies on dominance and
loop properties.
The pass is off by default and each target can opt-in by setting the
EnableShrinkWrap boolean to true in their derived class of TargetPassConfig.
This setting can also be overwritten on the command line by using
-enable-shrink-wrap.
Before you try out the pass for your target, make sure you properly fix your
emitProlog/emitEpilog/adjustForXXX method to cope with basic blocks that are not
necessarily the entry block.
** Design Decisions **
1. ShrinkWrap is its own pass right now. It could frankly be merged into PEI but
for debugging and clarity I thought it was best to have its own file.
2. Right now, we only support one save point and one restore point. At some
point we can expand this to several save point and restore point, the impacted
component would then be:
- The pass itself: New algorithm needed.
- MachineFrameInfo: Hold a list or set of Save/Restore point instead of one
pointer.
- PEI: Should loop over the save point and restore point.
Anyhow, at least for this first iteration, I do not believe this is interesting
to support the complex cases. We should revisit that when we motivating
examples.
Differential Revision: http://reviews.llvm.org/D9210
<rdar://problem/3201744>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236507 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
When using the N64 ABI, element-indices use the i64 type instead of i32.
In many cases, we can use iPTR to account for this but additional patterns
and pseudo's are also required.
This fixes most (but not quite all) failures in the test-suite when using
N64 and MSA together.
Reviewers: vkalintiris
Reviewed By: vkalintiris
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9342
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236494 91177308-0d34-0410-b5e6-96231b3b80d8
When forming an IT block from the first MOV here:
%R2<def> = t2MOVr %R0, pred:1, pred:%CPSR, opt:%noreg
%R3<def> = tMOVr %R0<kill>, pred:14, pred:%noreg
the move in to R3 is moved out of the IT block so that later instructions on the same predicate can be inside this block, and we can share the IT instruction.
However, when moving the R3 copy out of the IT block, we need to clear its kill flags for anything in use at this point in time, ie, R0 here.
This appeases the machine verifier which thought that R0 wasn't defined when used.
I have a test case, but its extremely register allocator specific. It would be too fragile to commit a test which depends on the register allocator here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236468 91177308-0d34-0410-b5e6-96231b3b80d8
and avoid cloning unused decls into every partition.
Module partitioning showed up as a source of significant overhead when I
profiled some trivial test cases. Avoiding the overhead of partitionging
for uncalled functions helps to mitigate this.
This change also means that it is no longer necessary to have a
LazyEmittingLayer underneath the CompileOnDemand layer, since the
CompileOnDemandLayer will not extract or emit function bodies until they are
called.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236465 91177308-0d34-0410-b5e6-96231b3b80d8
When deciding whether a value comes from the aggregate or inserted value of an
insertvalue instruction, we compare the indices against those of the location
we're interested in. One of the lists needs reversing because the input data is
backwards (so that modifications take place at the end of the SmallVector), but
we were reversing both before leading to incorrect results.
Should fix PR23408
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236457 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
The object format can be set to something other than MachO, e.g.
to use ELF-on-Darwin for MCJIT. This already works on Windows, so
there's no reason it shouldn't on Darwin.
Reviewers: lhames, grosbach
Subscribers: rafael, grosbach, t.p.northover, llvm-commits
Differential Revision: http://reviews.llvm.org/D6185
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236455 91177308-0d34-0410-b5e6-96231b3b80d8
A joined option always needs to have an argument, even if it's an empty one.
Clang would previously assert when trying to use --extra-warnings, which is
a flag alias for -W, which is a joined option.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236434 91177308-0d34-0410-b5e6-96231b3b80d8
At the moment, all subregs defined by the SystemZ target can be modified
independently of the wider register. E.g. writing to a GR32 does not
change the upper 32 bits of the GR64. Writing to an FP32 does not change
the lower 32 bits of the FP64.
Hoewver, the upcoming support for the vector extension redefines FP64 as
one half of a V128. Floating-point operations leave the other half of
a V128 in an unpredictable state, so it's no longer the case that writing
to an FP32 leaves the bits of the underlying register (the V128) alone.
I'd prefer to have separate subreg_ names for this situation, so that
it's obvious at a glance whether we're talking about a subreg that leaves
the other parts of the register alone.
No behavioral change intended.
Patch originally by Richard Sandiford.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236433 91177308-0d34-0410-b5e6-96231b3b80d8
We know what MemoryKind an operand has at the time we construct it,
so we might as well just record it in an unused part of the structure.
This makes it easier to add scatter/gather addresses later.
No behavioral change intended.
Patch originally by Richard Sandiford.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236432 91177308-0d34-0410-b5e6-96231b3b80d8
It seems SystemZTargetLowering::getTargetNodeName got out of sync with
some recent changes to the SystemZISD opcode list. Add back all the
missing opcodes (and re-sort to the same order as SystemISelLowering.h).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236430 91177308-0d34-0410-b5e6-96231b3b80d8
ScheduleDAGInstrs wasn't setting or clearing the kill flags on instructions inside bundles. This led to code such as this
%R3<def> = t2ANDrr %R0
BUNDLE %ITSTATE<imp-def,dead>, %R0<imp-use,kill>
t2IT 1, 24, %ITSTATE<imp-def>
R6<def,tied6> = t2ORRrr %R0<kill>, ...
being transformed to
BUNDLE %ITSTATE<imp-def,dead>, %R0<imp-use>
t2IT 1, 24, %ITSTATE<imp-def>
R6<def,tied6> = t2ORRrr %R0<kill>, ...
%R3<def> = t2ANDrr %R0<kill>
where the kill flag was removed from the BUNDLE instruction, but not the t2ORRrr inside it. The verifier then thought that
R0 was undefined when read by the AND.
This change make the toggleKillFlags method also check for bundles and toggle flags on bundled instructions.
Setting the kill flag is special cased as we only want to set the kill flag on the last instruction in the bundle.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236428 91177308-0d34-0410-b5e6-96231b3b80d8
Fixed some bugs in extend/truncate for AVX-512 target.
Removed VBROADCASTM (masked broadcast) node, since it is not used any more.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236420 91177308-0d34-0410-b5e6-96231b3b80d8
After r210687, windows_error does nothing but call mapWindowsError.
Other Windows/*.inc files directly call mapWindowsError. This patch
updates Path.inc and Process.inc to do the same.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236409 91177308-0d34-0410-b5e6-96231b3b80d8
Removed code that was replicating v8i16 'shift + mask' implementation that is done more nicely by making use of LowerScalarImmediateShift
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236388 91177308-0d34-0410-b5e6-96231b3b80d8
Seems we were setting the base address on the wrong DwarfCompileUnit
object so it wasn't being used when generating the ranges.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236377 91177308-0d34-0410-b5e6-96231b3b80d8
This patch adds the --load-address command line option to
llvm-pdbdump, which dumps all addresses assuming the module has
loaded at the specified address.
Additionally, this patch adds an option to llvm-pdbdump to support
dumping of public symbols (i.e. symbols with external linkage).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236342 91177308-0d34-0410-b5e6-96231b3b80d8
This reapplies r235060 and 235070, which were reverted because of test failures
in LLDB. The failure was caused because at moment RuntimeDyld is processing
relocations for all sections, irrespective of whether we actually load them
into memory or not, but RuntimeDyld was not actually remembering where in memory
the unrelocated section is. This commit includes a fix for that issue by
remembering that pointer, though the longer term fix should be to stop processing
unneeded sections.
Original Summary:
This allows us to get rid of the original unrelocated object file after
we're done processing relocations (but before applying them).
MachO and COFF already do not require this (currently we have temporary hacks
to prevent ownership from being released, but those are brittle and should be
removed soon).
The placeholder mechanism allowed the relocation resolver to look at original
object file to obtain more information that are required to apply the
relocations. This is usually necessary in two cases:
- For relocations targetting sub-word memory locations, there may be pieces
of the instruction at the target address which we should not override.
- Some relocations on some platforms allow an extra addend to be encoded in
their immediate fields.
The problem is that in the second case the information cannot be recovered
after the relocations have been applied once because they will have been
overridden. In the first case we also need to be careful to not use any bits
that aren't fixed and may have been overriden by applying a first relocation.
In the past both have been fixed by just looking at original object file. This
patch attempts to recover the information from the first by looking at the
relocated object file, while the extra addend in the second case is read
upon relocation processing and addend to the regular addend.
I have tested this on X86. Other platforms represent my best understanding
of how those relocations should work, but I may have missed something because
I do not have access to those platforms.
We will keep the ugly workarounds in place for a couple of days, so this commit
can be reverted if it breaks the bots.
Differential Revision: http://reviews.llvm.org/D9028
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236341 91177308-0d34-0410-b5e6-96231b3b80d8
This pass is responsible for constructing the EH registration object
that gets linked into fs:00, which is all it does in this change. In the
future, it will also insert stores to update the EH state number.
I considered keeping this functionality in WinEHPrepare, but it's pretty
separable and X86 specific. It has conceptually very little to do with
the task of WinEHPrepare, which is currently outlining. WinEHPrepare is
also in theory useful on ARM, but this logic is pretty x86 specific.
Reviewers: andrew.w.kaylor, majnemer
Differential Revision: http://reviews.llvm.org/D9422
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236339 91177308-0d34-0410-b5e6-96231b3b80d8
Converting from t2LDRs to tLDRr caused the shift argument to drop the internal flag. This would then throw machine verifier errors.
Unfortunately i'm having trouble reducing a test case. I'm going to keep trying, but so far its a scary combination of machine sinking, an 'and i1', loads feeding loads, and a bunch of code which shouldn't change IT block formation, but does. Its not useful to commit a test in that state as we have no way of knowing if it even hits this code reliably in future.
rdar://problem/20752113
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236333 91177308-0d34-0410-b5e6-96231b3b80d8
This patch fixes a bug where the YAML Output class emitted
a sequence of flow sequences without the '-' characters.
Before:
seq:
[ a, b ]
[ c, d ]
After:
seq:
- [ a, b ]
- [ c, d ]
Reviewers: Justin Bogner
Differential Revision: http://reviews.llvm.org/D9206
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236329 91177308-0d34-0410-b5e6-96231b3b80d8
