ArraySize * ElementSize
ElementSize * ArraySize
ArraySize << log2(ElementSize)
ElementSize << log2(ArraySize)
Refactor isArrayMallocHelper and delete isSafeToGetMallocArraySize, so that there is only 1 copy of the malloc array determining logic.
Update users of getMallocArraySize() to not bother calling isArrayMalloc() as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85421 91177308-0d34-0410-b5e6-96231b3b80d8
stuff) to programmatically control the current debug flavor. While
I'm at it, doxygenate Debug.h and clean it up.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85395 91177308-0d34-0410-b5e6-96231b3b80d8
Checks on Demand algorithm which looks at arbitrary branches instead of loop
iterations. This is GSoC work by Andre Tavares with only editorial changes
applied!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85382 91177308-0d34-0410-b5e6-96231b3b80d8
In the new world order, BlockAddress can have a BasicBlock operand.
This doesn't permute much, because if you have a ConstantExpr (or
anything more specific than Constant) we still know the operand has
to be a Constant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85375 91177308-0d34-0410-b5e6-96231b3b80d8
use it to control tail merging when there is a tradeoff between performance
and code size. When there is only 1 instruction in the common tail, we have
been merging. That can be good for code size but is a definite loss for
performance. Now we will avoid tail merging in that case when the
optimization level is "Aggressive", i.e., "-O3". Radar 7338114.
Since the IfConversion pass invokes BranchFolding, it too needs to know
the optimization level. Note that I removed the RegisterPass instantiation
for IfConversion because it required a default constructor. If someone
wants to keep that for some reason, we can add a default constructor with
a hard-wired optimization level.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85346 91177308-0d34-0410-b5e6-96231b3b80d8
being destroyed. This allows users to run global optimizations like globaldce
even after some functions have been jitted.
This patch also removes the Function* parameter to
JITEventListener::NotifyFreeingMachineCode() since it can cause that to be
called when the Function is partially destroyed. This change will be even more
helpful later when I think we'll want to allow machine code to actually outlive
its Function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85182 91177308-0d34-0410-b5e6-96231b3b80d8
Remove LowerAllocations pass.
Update some more passes to treate free calls just like they were treating FreeInst.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85176 91177308-0d34-0410-b5e6-96231b3b80d8
GEPs (more than one non-zero index) into simple GEPs (at most one
non-zero index). In some simple experiments using this it's not
uncommon to see 3% overall code size wins, because it exposes
redundancies that can be eliminated, however it's tricky to use
because instcombine aggressively undoes the work that this pass does.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85144 91177308-0d34-0410-b5e6-96231b3b80d8
bootstrapping. It's not safe to leave identity subreg_to_reg and insert_subreg
around.
- Relax register scavenging to allow use of partially "not-live" registers. It's
common for targets to operate on registers where the top bits are undef. e.g.
s0 =
d0 = insert_subreg d0<undef>, s0, 1
...
= d0
When the insert_subreg is eliminated by the coalescer, the scavenger used to
complain. The previous fix was to keep to insert_subreg around. But that's
brittle and it's overly conservative when we want to use the scavenger to
allocate registers. It's actually legal and desirable for other instructions
to use the "undef" part of d0. e.g.
s0 =
d0 = insert_subreg d0<undef>, s0, 1
...
s1 =
= s1
= d0
We probably need add a "partial-undef" marker on machine operand so the
machine verifier would not complain.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85091 91177308-0d34-0410-b5e6-96231b3b80d8
used elsewhere - an exit block is a block outside the loop branched to
from within the loop. An exiting block is a block inside the loop that
branches out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85019 91177308-0d34-0410-b5e6-96231b3b80d8
Update all analysis passes and transforms to treat free calls just like FreeInst.
Remove RaiseAllocations and all its tests since FreeInst no longer needs to be raised.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84987 91177308-0d34-0410-b5e6-96231b3b80d8
compiled.
When functions are compiled, they accumulate references in the JITResolver's
stub maps. This patch removes those references when the functions are
destroyed. It's illegal to destroy a Function when any thread may still try to
call its machine code.
This patch also updates r83987 to use ValueMap instead of explicit CallbackVHs
and fixes a couple "do stuff inside assert()" bugs from r84522.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84975 91177308-0d34-0410-b5e6-96231b3b80d8
even when keys get RAUWed and deleted during its lifetime. By default the keys
act like WeakVHs, but users can pass a third template parameter to configure
how updates work and whether to do anything beyond updating the map on each
action.
It's also possible to automatically acquire a lock around ValueMap updates
triggered by RAUWs and deletes, to support the ExecutionEngine.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84890 91177308-0d34-0410-b5e6-96231b3b80d8
Analysis/ConstantFolding.cpp. This doesn't change the behavior of
instcombine but makes other clients of ConstantFoldInstruction
able to handle loads. This was partially extracted from Eli's patch
in PR3152.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84836 91177308-0d34-0410-b5e6-96231b3b80d8
- i < getNumElements() instead of getNumElements() > i
- Make setParent() private
- Fix use of resizeOperands
- Reset HasMetadata bit after removing all metadata attached to an instruction
- Efficient use of iterators
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84765 91177308-0d34-0410-b5e6-96231b3b80d8
s/validName/isValidName/g
s/with an Instruction/to an Instruction/g
s/RegisterMDKind/registerMDKind/g
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84689 91177308-0d34-0410-b5e6-96231b3b80d8
JITEmitter.
I'm gradually making Functions auto-remove themselves from the JIT when they're
destroyed. In this case, the Function needs to be removed from the JITEmitter,
but the map recording which Functions need to be removed lived behind the
JITMemoryManager interface, which made things difficult.
This patch replaces the deallocateMemForFunction(Function*) method with a pair
of methods deallocateFunctionBody(void *) and deallocateExceptionTable(void *)
corresponding to the two startFoo/endFoo pairs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84651 91177308-0d34-0410-b5e6-96231b3b80d8
appropriate restore location for the spill as well as perform the actual
save and restore.
The Thumb1 target uses this to make sure R12 is not clobbered while a spilled
scavenger register is live there.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84554 91177308-0d34-0410-b5e6-96231b3b80d8
The JITResolver maps Functions to their canonical stubs and all callsites for
lazily-compiled functions to their target Functions. To make Function
destruction work, I'm going to need to remove all callsites on destruction, so
this patch also adds the reverse mapping for that.
There was an incorrect assumption in here that the only stub for a function
would be the one caused by needing to lazily compile it, while x86-64 far calls
and dlsym-stubs could also cause such stubs, but I didn't look for a test case
that the assumption broke.
This also adds DenseMapInfo<AssertingVH> so I can use DenseMaps instead of
std::maps.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84522 91177308-0d34-0410-b5e6-96231b3b80d8
stack slots and giving them different PseudoSourceValue's did not fix the
problem of post-alloc scheduling miscompiling llvm itself.
- Apply Dan's conservative workaround by assuming any non fixed stack slots can
alias other memory locations. This means a load from spill slot #1 cannot
move above a store of spill slot #2.
- Enable post-alloc scheduling for x86 at optimization leverl Default and above.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84424 91177308-0d34-0410-b5e6-96231b3b80d8
Update testcases that rely on malloc insts being present.
Also prematurely remove MallocInst handling from IndMemRemoval and RaiseAllocations to help pass tests in this incremental step.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84292 91177308-0d34-0410-b5e6-96231b3b80d8
identifying the malloc as a non-array malloc. This broke GlobalOpt's optimization of stores of mallocs
to global variables.
The fix is to classify malloc's into 3 categories:
1. non-array mallocs
2. array mallocs whose array size can be determined
3. mallocs that cannot be determined to be of type 1 or 2 and cannot be optimized
getMallocArraySize() returns NULL for category 3, and all users of this function must avoid their
malloc optimization if this function returns NULL.
Eventually, currently unexpected codegen for computing the malloc's size argument will be supported in
isArrayMalloc() and getMallocArraySize(), extending malloc optimizations to those examples.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84199 91177308-0d34-0410-b5e6-96231b3b80d8
so get rid of eh.selector.i64 and rename eh.selector.i32 to eh.selector.
Likewise for eh.typeid.for. This aligns us with gcc, which always uses a
32 bit value for the selector on all platforms. My understanding is that
the register allocator used to assert if the selector intrinsic size didn't
match the pointer size, and this was the reason for introducing the two
variants. However my testing shows that this is no longer the case (I
fixed some bugs in selector lowering yesterday, and some more today in the
fastisel path; these might have caused the original problems).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84106 91177308-0d34-0410-b5e6-96231b3b80d8
truncating an SDValue (depending on whether the target
type is bigger or smaller than the value's type); or zero
extending or truncating it. Use it in a few places (this
seems to be a popular operation, but I only modified cases
of it in SelectionDAGBuild). In particular, the eh_selector
lowering was doing this wrong due to a repeated rather than
inverted test, fixed with this change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84027 91177308-0d34-0410-b5e6-96231b3b80d8
GlobalValue is destroyed. Function destruction still leaks machine code and
can crash on leaked stubs, but this is some progress.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83987 91177308-0d34-0410-b5e6-96231b3b80d8
bootstrap of FSF-style PPC, so there is some
reason to believe the original bug (which was
never analyzed) has been fixed, probably by
82266.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83871 91177308-0d34-0410-b5e6-96231b3b80d8
not just at the end. Add a big comment explaining when this could
be useful (which never happens for jump threading).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83741 91177308-0d34-0410-b5e6-96231b3b80d8
a Value* to a WeakVH was constructing a temporary WeakVH
(due to the implicit assignment operator). This avoids
that cost.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83704 91177308-0d34-0410-b5e6-96231b3b80d8
is trivially rematerializable and integrate it into
TargetInstrInfo::isTriviallyReMaterializable. This way, all places that
need to know whether an instruction is rematerializable will get the
same answer.
This enables the useful parts of the aggressive-remat option by
default -- using AliasAnalysis to determine whether a memory location
is invariant, and removes the questionable parts -- rematting operations
with virtual register inputs that may not be live everywhere.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83687 91177308-0d34-0410-b5e6-96231b3b80d8
While recording beginning of a function, use scope info from the first location entry instead of just relying on first location entry itself.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83684 91177308-0d34-0410-b5e6-96231b3b80d8
mappings, which could cause errors and assert-failures. This patch fixes that,
adds a test, and refactors the global-mapping-removal code into a single place.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83678 91177308-0d34-0410-b5e6-96231b3b80d8
constants used in inlining heuristics (especially
those used in more than one file). No functional change.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83675 91177308-0d34-0410-b5e6-96231b3b80d8
to declare that they preserve other passes without needing to pull in
additional header file or library dependencies. Convert MachineFunctionPass
and CodeGenLICM to make use of this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83555 91177308-0d34-0410-b5e6-96231b3b80d8
"LoopVR's logic was copied into ScalarEvolution::getUnsignedRange and
::getSignedRange. Please delete LoopVR."
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83531 91177308-0d34-0410-b5e6-96231b3b80d8
implementations with a new MachineInstr::isInvariantLoad, which uses
MachineMemOperands and is target-independent. This brings MachineLICM
and other functionality to targets which previously lacked an
isInvariantLoad implementation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83475 91177308-0d34-0410-b5e6-96231b3b80d8
a virtual register to eliminate a frame index, it can return that register
and the constant stored there to PEI to track. When scavenging to allocate
for those registers, PEI then tracks the last-used register and value, and
if it is still available and matches the value for the next index, reuses
the existing value rather and removes the re-materialization instructions.
Fancier tracking and adjustment of scavenger allocations to keep more
values live for longer is possible, but not yet implemented and would likely
be better done via a different, less special-purpose, approach to the
problem.
eliminateFrameIndex() is modified so the target implementations can return
the registers they wish to be tracked for reuse.
ARM Thumb1 implements and utilizes the new mechanism. All other targets are
simply modified to adjust for the changed eliminateFrameIndex() prototype.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83467 91177308-0d34-0410-b5e6-96231b3b80d8
intuitive.
It does NOT update the value if the key is already in the map,
it also returns false if the key is already in the map, regardless
if the value matched.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83458 91177308-0d34-0410-b5e6-96231b3b80d8
out of it, and jump threading, condprop and gvn are now getting
most of the benefit. This was approved by Nicholas and Nicolas.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83390 91177308-0d34-0410-b5e6-96231b3b80d8
spill slot. When frame references are via the frame pointer, they will be
negative, but Thumb1 load/store instructions only allow positive immediate
offsets. Instead, Thumb1 will spill to R12.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83336 91177308-0d34-0410-b5e6-96231b3b80d8
question, can we get rid of the BasicBlock versions of all inserters
and use Head == 0 to indicate the old case when GetInsertBlock == 0?
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83216 91177308-0d34-0410-b5e6-96231b3b80d8
set, these flags indicate the instructions source / def operands have special
register allocation requirement that are not captured in their register classes.
Post-allocation passes (e.g. post-alloc scheduler) should not change their
allocations. e.g. ARM::LDRD require the two definitions to be allocated
even / odd register pair.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83196 91177308-0d34-0410-b5e6-96231b3b80d8
Add a new TargetLoweringObjectFileMachO::getConstTextCoalSection method to
get access to that section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83178 91177308-0d34-0410-b5e6-96231b3b80d8
to emit target-specific things at the beginning of the asm output. This
fixes a problem for PPC, where the text sections are not being kept together
as expected. The base class doInitialization code calls DW->BeginModule()
which emits a bunch of DWARF section directives. The PPC doInitialization
code then emits all the TEXT section directives, with the intention that they
will be kept together. But as I understand it, the Darwin assembler treats
the default TEXT section as a special case and moves it to the beginning of
the file, which means that all those DWARF sections are in the middle of
the text. With this change, the EmitStartOfAsmFile hook is called before
the DWARF section directives are emitted, so that all the PPC text section
directives come out right at the beginning of the file.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83176 91177308-0d34-0410-b5e6-96231b3b80d8
basic blocks that are so long that their size overflows a short.
Also assert that overflow does not happen in the future, as requested by Evan.
This fixes PR4401.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83159 91177308-0d34-0410-b5e6-96231b3b80d8
information. This allows arbitrary code involving DW_OP_plus_uconst
and DW_OP_deref. The scheme allows for easy extention to include,
any, or all of the DW_OP_ opcodes. I thought about just exposing all
of them, but, wasn't sure if people wanted the dwarf opcodes exposed
in the api. Is that a layering violation?
With this scheme, the entire existing block scheme used by llvm-gcc
can be switched over to the new scheme. I think that would be
cleaner, as then the compiler specific bits are not present in llvm
proper. Before the old code can be yanked however, similar code in
clang would have to be removed.
Next up, more testing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83120 91177308-0d34-0410-b5e6-96231b3b80d8
unused DECLARE instruction.
KILL is not yet used anywhere, it will replace TargetInstrInfo::IMPLICIT_DEF
in the places where IMPLICIT_DEF is just used to alter liveness of physical
registers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83006 91177308-0d34-0410-b5e6-96231b3b80d8
the PassManager code into a regular verifyAnalysis method.
Also, reorganize loop verification. Make the LoopPass infrastructure
call verifyLoop as needed instead of having LoopInfo::verifyAnalysis
check every loop in the function after each looop pass. Add a new
command-line argument, -verify-loop-info, to enable the expensive
full checking.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82952 91177308-0d34-0410-b5e6-96231b3b80d8
code that stops the timer doesn't have to search to find the timer
object before it stops the timer. This avoids a lock acquisition
and a few other things done with the timer running.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82949 91177308-0d34-0410-b5e6-96231b3b80d8
setenv(). This patch just disables the test rather than getting putenv() to
work. Thanks to Sandeep Patel for reporting the problem.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82797 91177308-0d34-0410-b5e6-96231b3b80d8
- Allocate MachineMemOperands and MachineMemOperand lists in MachineFunctions.
This eliminates MachineInstr's std::list member and allows the data to be
created by isel and live for the remainder of codegen, avoiding a lot of
copying and unnecessary translation. This also shrinks MemSDNode.
- Delete MemOperandSDNode. Introduce MachineSDNode which has dedicated
fields for MachineMemOperands.
- Change MemSDNode to have a MachineMemOperand member instead of its own
fields with the same information. This introduces some redundancy, but
it's more consistent with what MachineInstr will eventually want.
- Ignore alignment when searching for redundant loads for CSE, but remember
the greatest alignment.
Target-specific code which previously used MemOperandSDNodes with generic
SDNodes now use MemIntrinsicSDNodes, with opcodes in a designated range
so that the SelectionDAG framework knows that MachineMemOperand information
is available.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82794 91177308-0d34-0410-b5e6-96231b3b80d8
naming scheme used in SelectionDAG, where there are multiple kinds
of "target" nodes, but "machine" nodes are nodes which represent
a MachineInstr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82790 91177308-0d34-0410-b5e6-96231b3b80d8
For the AAPCS ABI, SP must always be 4-byte aligned, and at any "public
interface" it must be 8-byte aligned. For the older ARM APCS ABI, the stack
alignment is just always 4 bytes. For X86, we currently align SP at
entry to a function (e.g., to 16 bytes for Darwin), but no stack alignment
is needed at other times, such as for a leaf function.
After discussing this with Dan, I decided to go with the approach of adding
a new "TransientStackAlignment" field to TargetFrameInfo. This value
specifies the stack alignment that must be maintained even in between calls.
It defaults to 1 except for ARM, where it is 4. (Some other targets may
also want to set this if they have similar stack requirements. It's not
currently required for PPC because it sets targetHandlesStackFrameRounding
and handles the alignment in target-specific code.) The existing StackAlignment
value specifies the alignment upon entry to a function, which is how we've
been using it anyway.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82767 91177308-0d34-0410-b5e6-96231b3b80d8
this adjustment does not change the direction or the signs of the object
offsets, and the details of the offset calculations can be target-specific.
Also mention that for most targets this value is only used to generate debug
info.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82750 91177308-0d34-0410-b5e6-96231b3b80d8
of the defs are processed.
Also fix a implicit_def propagation bug: a implicit_def of a physical register
should be applied to uses of the sub-registers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82616 91177308-0d34-0410-b5e6-96231b3b80d8
two different places for printing MachineMemOperands.
Drop the virtual from Value::dump and instead give Value a
protected virtual hook that can be overridden by subclasses
to implement custom printing. This lets printing be more
consistent, and simplifies printing of PseudoSourceValue
values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82599 91177308-0d34-0410-b5e6-96231b3b80d8
buffer", while we work out a solution.
Dan convinced me that making debugging annoying for him is worse than 10x being
slower for me. :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82553 91177308-0d34-0410-b5e6-96231b3b80d8
- This also fixes a dereference of std::string::end, which makes MSVC unhappy and was causing all the static analyzer clang tests to fail.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82517 91177308-0d34-0410-b5e6-96231b3b80d8
This is designed for tracking a value even when it might move (like WeakVH), but it is an error to delete the referenced value (unlike WeakVH0. TrackingVH is templated like AssertingVH on the tracked Value subclass, it is an error to RAUW a tracked value to an incompatible type.
For implementation reasons the latter error is only diagnosed on accesses to a mis-RAUWed TrackingVH, because we don't want a virtual interface in a templated class.
The former error is also only diagnosed on access, so that clients are allowed to delete a tracked value, as long as they don't use it. This makes it easier for the client to reason about destruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82506 91177308-0d34-0410-b5e6-96231b3b80d8
the base pointer, without the offset. This matches MemSDNode's
new alignment behavior, and holds more interesting information.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82473 91177308-0d34-0410-b5e6-96231b3b80d8
is.
- The problem is that formatted_ostream forces its underlying buffer to be
unbuffered, so if some client happens to wrap a formatted_ostream around
something, but still use the underlying stream, then we can end up writing on
a fully unbuffered output (which was never intended to be unbuffered).
- This makes clang (and presumably llvm-gcc) -emit-llvm -S a mere 10x faster.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82434 91177308-0d34-0410-b5e6-96231b3b80d8
feature, either build the JIT in debug mode to enable it by default or pass
-jit-emit-debug to lli.
Right now, the only debug information that this communicates to GDB is call
frame information, since it's already being generated to support exceptions in
the JIT. Eventually, when DWARF generation isn't tied so tightly to AsmPrinter,
it will be easy to push that information to GDB through this interface.
Here's a step-by-step breakdown of how the feature works:
- The JIT generates the machine code and DWARF call frame info
(.eh_frame/.debug_frame) for a function into memory.
- The JIT copies that info into an in-memory ELF file with a symbol for the
function.
- The JIT creates a code entry pointing to the ELF buffer and adds it to a
linked list hanging off of a global descriptor at a special symbol that GDB
knows about.
- The JIT calls a function marked noinline that GDB knows about and has put an
internal breakpoint in.
- GDB catches the breakpoint and reads the global descriptor to look for new
code.
- When sees there is new code, it reads the ELF from the inferior's memory and
adds it to itself as an object file.
- The JIT continues, and the next time we stop the program, we are able to
produce a proper backtrace.
Consider running the following program through the JIT:
#include <stdio.h>
void baz(short z) {
long w = z + 1;
printf("%d, %x\n", w, *((int*)NULL)); // SEGFAULT here
}
void bar(short y) {
int z = y + 1;
baz(z);
}
void foo(char x) {
short y = x + 1;
bar(y);
}
int main(int argc, char** argv) {
char x = 1;
foo(x);
}
Here is a backtrace before this patch:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x2aaaabdfbd10 (LWP 25476)]
0x00002aaaabe7d1a8 in ?? ()
(gdb) bt
#0 0x00002aaaabe7d1a8 in ?? ()
#1 0x0000000000000003 in ?? ()
#2 0x0000000000000004 in ?? ()
#3 0x00032aaaabe7cfd0 in ?? ()
#4 0x00002aaaabe7d12c in ?? ()
#5 0x00022aaa00000003 in ?? ()
#6 0x00002aaaabe7d0aa in ?? ()
#7 0x01000002abe7cff0 in ?? ()
#8 0x00002aaaabe7d02c in ?? ()
#9 0x0100000000000001 in ?? ()
#10 0x00000000014388e0 in ?? ()
#11 0x00007fff00000001 in ?? ()
#12 0x0000000000b870a2 in llvm::JIT::runFunction (this=0x1405b70,
F=0x14024e0, ArgValues=@0x7fffffffe050)
at /home/rnk/llvm-gdb/lib/ExecutionEngine/JIT/JIT.cpp:395
#13 0x0000000000baa4c5 in llvm::ExecutionEngine::runFunctionAsMain
(this=0x1405b70, Fn=0x14024e0, argv=@0x13f06f8, envp=0x7fffffffe3b0)
at /home/rnk/llvm-gdb/lib/ExecutionEngine/ExecutionEngine.cpp:377
#14 0x00000000007ebd52 in main (argc=2, argv=0x7fffffffe398,
envp=0x7fffffffe3b0) at /home/rnk/llvm-gdb/tools/lli/lli.cpp:208
And a backtrace after this patch:
Program received signal SIGSEGV, Segmentation fault.
0x00002aaaabe7d1a8 in baz ()
(gdb) bt
#0 0x00002aaaabe7d1a8 in baz ()
#1 0x00002aaaabe7d12c in bar ()
#2 0x00002aaaabe7d0aa in foo ()
#3 0x00002aaaabe7d02c in main ()
#4 0x0000000000b870a2 in llvm::JIT::runFunction (this=0x1405b70,
F=0x14024e0, ArgValues=...)
at /home/rnk/llvm-gdb/lib/ExecutionEngine/JIT/JIT.cpp:395
#5 0x0000000000baa4c5 in llvm::ExecutionEngine::runFunctionAsMain
(this=0x1405b70, Fn=0x14024e0, argv=..., envp=0x7fffffffe3c0)
at /home/rnk/llvm-gdb/lib/ExecutionEngine/ExecutionEngine.cpp:377
#6 0x00000000007ebd52 in main (argc=2, argv=0x7fffffffe3a8,
envp=0x7fffffffe3c0) at /home/rnk/llvm-gdb/tools/lli/lli.cpp:208
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82418 91177308-0d34-0410-b5e6-96231b3b80d8
stringref because they may not be nul terminated. For options like -Lfoo
this now avoids a O(n) temporary std::strings where N is the length of
the string after -L.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82345 91177308-0d34-0410-b5e6-96231b3b80d8