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* Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Geoff Berry2018-02-271-3/+3
| | | | | | | | Re-enable commit r323991 now that r325931 has been committed to make MachineOperand::isRenamable() check more conservative w.r.t. code changes and opt-in on a per-target basis. llvm-svn: 326208
* Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Quentin Colombet2018-02-171-3/+3
| | | | | | | | | | | | | | | | | This reverts commit r323991. This commit breaks target that don't model all the register constraints in TableGen. So far the workaround was to set the hasExtraXXXRegAllocReq, but it proves that it doesn't cover all the cases. For instance, when mutating an instruction (like in the lowering of COPYs) the isRenamable flag is not properly updated. The same problem will happen when attaching machine operand from one instruction to another. Geoff Berry is working on a fix in https://reviews.llvm.org/D43042. llvm-svn: 325421
* [MachineCopyPropagation] Extend pass to do COPY source forwardingGeoff Berry2018-02-011-3/+3
| | | | | | | | | | | | | | | | | | | | | | Summary: This change extends MachineCopyPropagation to do COPY source forwarding and adds an additional run of the pass to the default pass pipeline just after register allocation. This version of this patch uses the newly added MachineOperand::isRenamable bit to avoid forwarding registers is such a way as to violate constraints that aren't captured in the Machine IR (e.g. ABI or ISA constraints). This change is a continuation of the work started in D30751. Reviewers: qcolombet, javed.absar, MatzeB, jonpa, tstellar Subscribers: tpr, mgorny, mcrosier, nhaehnle, nemanjai, jyknight, hfinkel, arsenm, inouehrs, eraman, sdardis, guyblank, fedor.sergeev, aheejin, dschuff, jfb, myatsina, llvm-commits Differential Revision: https://reviews.llvm.org/D41835 llvm-svn: 323991
* Revert "Re-enable "[MachineCopyPropagation] Extend pass to do COPY source ↵Geoff Berry2017-10-031-3/+3
| | | | | | | | | | forwarding"" This reverts commit r314729. Another bug has been encountered in an out-of-tree target reported by Quentin. llvm-svn: 314814
* Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Geoff Berry2017-10-021-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Issues addressed since original review: - Avoid bug in regalloc greedy/machine verifier when forwarding to use in an instruction that re-defines the same virtual register. - Fixed bug when forwarding to use in EarlyClobber instruction slot. - Fixed incorrect forwarding to register definitions that showed up in explicit_uses() iterator (e.g. in INLINEASM). - Moved removal of dead instructions found by LiveIntervals::shrinkToUses() outside of loop iterating over instructions to avoid instructions being deleted while pointed to by iterator. - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907. - The pass no longer forwards COPYs to physical register uses, since doing so can break code that implicitly relies on the physical register number of the use. - The pass no longer forwards COPYs to undef uses, since doing so can break the machine verifier by creating LiveRanges that don't end on a use (since the undef operand is not considered a use). [MachineCopyPropagation] Extend pass to do COPY source forwarding This change extends MachineCopyPropagation to do COPY source forwarding. This change also extends the MachineCopyPropagation pass to be able to be run during register allocation, after physical registers have been assigned, but before the virtual registers have been re-written, which allows it to remove virtual register COPY LiveIntervals that become dead through the forwarding of all of their uses. llvm-svn: 314729
* Revert "Re-enable "[MachineCopyPropagation] Extend pass to do COPY source ↵Sam McCall2017-09-041-3/+3
| | | | | | | | | | forwarding"" This crashes on boringSSL on PPC (will send reduced testcase) This reverts commit r312328. llvm-svn: 312490
* Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Geoff Berry2017-09-011-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | Issues addressed since original review: - Moved removal of dead instructions found by LiveIntervals::shrinkToUses() outside of loop iterating over instructions to avoid instructions being deleted while pointed to by iterator. - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907. - The pass no longer forwards COPYs to physical register uses, since doing so can break code that implicitly relies on the physical register number of the use. - The pass no longer forwards COPYs to undef uses, since doing so can break the machine verifier by creating LiveRanges that don't end on a use (since the undef operand is not considered a use). [MachineCopyPropagation] Extend pass to do COPY source forwarding This change extends MachineCopyPropagation to do COPY source forwarding. This change also extends the MachineCopyPropagation pass to be able to be run during register allocation, after physical registers have been assigned, but before the virtual registers have been re-written, which allows it to remove virtual register COPY LiveIntervals that become dead through the forwarding of all of their uses. llvm-svn: 312328
* Revert r312154 "Re-enable "[MachineCopyPropagation] Extend pass to do COPY ↵Hans Wennborg2017-08-301-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | source forwarding"" It caused PR34387: Assertion failed: (RegNo < NumRegs && "Attempting to access record for invalid register number!") > Issues identified by buildbots addressed since original review: > - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907. > - The pass no longer forwards COPYs to physical register uses, since > doing so can break code that implicitly relies on the physical > register number of the use. > - The pass no longer forwards COPYs to undef uses, since doing so > can break the machine verifier by creating LiveRanges that don't > end on a use (since the undef operand is not considered a use). > > [MachineCopyPropagation] Extend pass to do COPY source forwarding > > This change extends MachineCopyPropagation to do COPY source forwarding. > > This change also extends the MachineCopyPropagation pass to be able to > be run during register allocation, after physical registers have been > assigned, but before the virtual registers have been re-written, which > allows it to remove virtual register COPY LiveIntervals that become dead > through the forwarding of all of their uses. llvm-svn: 312178
* Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Geoff Berry2017-08-301-3/+3
| | | | | | | | | | | | | | | | | | | | | | | Issues identified by buildbots addressed since original review: - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907. - The pass no longer forwards COPYs to physical register uses, since doing so can break code that implicitly relies on the physical register number of the use. - The pass no longer forwards COPYs to undef uses, since doing so can break the machine verifier by creating LiveRanges that don't end on a use (since the undef operand is not considered a use). [MachineCopyPropagation] Extend pass to do COPY source forwarding This change extends MachineCopyPropagation to do COPY source forwarding. This change also extends the MachineCopyPropagation pass to be able to be run during register allocation, after physical registers have been assigned, but before the virtual registers have been re-written, which allows it to remove virtual register COPY LiveIntervals that become dead through the forwarding of all of their uses. llvm-svn: 312154
* Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding" ↵Geoff Berry2017-08-181-3/+3
| | | | | | | | | | | round 2 This reverts commit r311135. sanitizer-x86_64-linux-android buildbot is timing out with just this patch applied. llvm-svn: 311142
* Re-enable "[MachineCopyPropagation] Extend pass to do COPY source ↵Geoff Berry2017-08-171-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | forwarding" Two issues identified by buildbots were addressed: - The pass no longer forwards COPYs to physical register uses, since doing so can break code that implicitly relies on the physical register number of the use. - The pass no longer forwards COPYs to undef uses, since doing so can break the machine verifier by creating LiveRanges that don't end on a use (since the undef operand is not considered a use). [MachineCopyPropagation] Extend pass to do COPY source forwarding This change extends MachineCopyPropagation to do COPY source forwarding. This change also extends the MachineCopyPropagation pass to be able to be run during register allocation, after physical registers have been assigned, but before the virtual registers have been re-written, which allows it to remove virtual register COPY LiveIntervals that become dead through the forwarding of all of their uses. Reviewers: qcolombet, javed.absar, MatzeB, jonpa Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny Differential Revision: https://reviews.llvm.org/D30751 llvm-svn: 311135
* Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding"Geoff Berry2017-08-171-3/+3
| | | | | | | | | | This reverts commit r311038. Several buildbots are breaking, and at least one appears to be due to the forwarding of physical regs enabled by this change. Reverting while I investigate further. llvm-svn: 311062
* [MachineCopyPropagation] Extend pass to do COPY source forwardingGeoff Berry2017-08-161-3/+3
| | | | | | | | | | | | | | | | | | This change extends MachineCopyPropagation to do COPY source forwarding. This change also extends the MachineCopyPropagation pass to be able to be run during register allocation, after physical registers have been assigned, but before the virtual registers have been re-written, which allows it to remove virtual register COPY LiveIntervals that become dead through the forwarding of all of their uses. Reviewers: qcolombet, javed.absar, MatzeB, jonpa Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny Differential Revision: https://reviews.llvm.org/D30751 llvm-svn: 311038
* [DAG] Improve Aliasing of operations to static allocaNirav Dave2017-07-181-21/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Re-recommiting after landing DAG extension-crash fix. Recommiting after adding check to avoid miscomputing alias information on addresses of the same base but different subindices. Memory accesses offset from frame indices may alias, e.g., we may merge write from function arguments passed on the stack when they are contiguous. As a result, when checking aliasing, we consider the underlying frame index's offset from the stack pointer. Static allocs are realized as stack objects in SelectionDAG, but its offset is not set until post-DAG causing DAGCombiner's alias check to consider access to static allocas to frequently alias. Modify isAlias to consider access between static allocas and access from other frame objects to be considered aliasing. Many test changes are included here. Most are fixes for tests which indirectly relied on our aliasing ability and needed to be modified to preserve their original intent. The remaining tests have minor improvements due to relaxed ordering. The exception is CodeGen/X86/2011-10-19-widen_vselect.ll which has a minor degradation dispite though the pre-legalized DAG is improved. Reviewers: rnk, mkuper, jonpa, hfinkel, uweigand Reviewed By: rnk Subscribers: sdardis, nemanjai, javed.absar, llvm-commits Differential Revision: https://reviews.llvm.org/D33345 llvm-svn: 308350
* Revert r308025 due to uncovering a crash in SelectionDAG. This is filedChandler Carruth2017-07-181-21/+21
| | | | | | | | | with a minimal test case in http://llvm.org/PR33833. Original commit message: Improve Aliasing of operations to static alloca llvm-svn: 308271
* Improve Aliasing of operations to static allocaNirav Dave2017-07-141-21/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Recommiting after adding check to avoid miscomputing alias information on addresses of the same base but different subindices. Memory accesses offset from frame indices may alias, e.g., we may merge write from function arguments passed on the stack when they are contiguous. As a result, when checking aliasing, we consider the underlying frame index's offset from the stack pointer. Static allocs are realized as stack objects in SelectionDAG, but its offset is not set until post-DAG causing DAGCombiner's alias check to consider access to static allocas to frequently alias. Modify isAlias to consider access between static allocas and access from other frame objects to be considered aliasing. Many test changes are included here. Most are fixes for tests which indirectly relied on our aliasing ability and needed to be modified to preserve their original intent. The remaining tests have minor improvements due to relaxed ordering. The exception is CodeGen/X86/2011-10-19-widen_vselect.ll which has a minor degradation dispite though the pre-legalized DAG is improved. Reviewers: rnk, mkuper, jonpa, hfinkel, uweigand Reviewed By: rnk Subscribers: sdardis, nemanjai, javed.absar, llvm-commits Differential Revision: https://reviews.llvm.org/D33345 llvm-svn: 308025
* Revert "[DAG] Improve Aliasing of operations to static alloca"Matthias Braun2017-07-101-21/+21
| | | | | | | | | Reverting as it breaks tramp3d-v4 in the llvm test-suite. I added some comments to https://reviews.llvm.org/D33345 about it. This reverts commit r307546. llvm-svn: 307589
* [DAG] Improve Aliasing of operations to static allocaNirav Dave2017-07-101-21/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Memory accesses offset from frame indices may alias, e.g., we may merge write from function arguments passed on the stack when they are contiguous. As a result, when checking aliasing, we consider the underlying frame index's offset from the stack pointer. Static allocs are realized as stack objects in SelectionDAG, but its offset is not set until post-DAG causing DAGCombiner's alias check to consider access to static allocas to frequently alias. Modify isAlias to consider access between static allocas and access from other frame objects to be considered aliasing. Many test changes are included here. Most are fixes for tests which indirectly relied on our aliasing ability and needed to be modified to preserve their original intent. The remaining tests have minor improvements due to relaxed ordering. The exception is CodeGen/X86/2011-10-19-widen_vselect.ll which has a minor degradation dispite though the pre-legalized DAG is improved. Reviewers: rnk, mkuper, jonpa, hfinkel, uweigand Reviewed By: rnk Subscribers: sdardis, nemanjai, javed.absar, llvm-commits Differential Revision: https://reviews.llvm.org/D33345 llvm-svn: 307546
* Add placeholder for more extensive verification of psuedo opsPhilip Reames2017-06-021-1/+1
| | | | | | | | | | This initial patch doesn't actually do much useful. It's just to show where the new code goes. Once this is in, I'll extend the verification logic to check more useful properties. For those curious, the more complicated version of this patch already found one very suspicious thing. Differential Revision: https://reviews.llvm.org/D33819 llvm-svn: 304564
* [Statepoints] Reuse stack slots more than once within a basic blockPhilip Reames2016-12-131-0/+30
| | | | | | | | | | The stack slot reuse code had a really amusing bug. We ended up only reusing a stack slot exact once (initial use + reuse) within a basic block. If we had a third statepoint to process, we ended up allocating a new set of stack slots. If we crossed a basic block boundary, the set got cleared. As a result, code which is invoke heavy doesn't see the problem, but multiple calls within a basic block does. Net result: as we optimize invokes into calls, lowering gets worse. The root error here is that the bitmap uses by the custom allocator wasn't kept in sync. The result was that we ended up resizing the bitmap on the next statepoint (to handle the cross block case), reset the bit once, but then never reset it again. Differential Revision: https://reviews.llvm.org/D25243 llvm-svn: 289509
* Implemented stack symbol table ordering/packing optimization to improve data ↵Zia Ansari2016-02-151-1/+1
| | | | | | | | locality and code size from SP/FP offset encoding. Differential Revision: http://reviews.llvm.org/D15393 llvm-svn: 260917
* [gc.statepoint] Change gc.statepoint intrinsic's return type to token type ↵Chen Li2015-12-261-27/+27
| | | | | | | | | | | | | | instead of i32 type Summary: This patch changes gc.statepoint intrinsic's return type to token type instead of i32 type. Using token types could prevent LLVM to merge different gc.statepoint nodes into PHI nodes and cause further problems with gc relocations. The patch also changes the way on how gc.relocate and gc.result look for their corresponding gc.statepoint on unwind path. The current implementation uses the selector value extracted from a { i8*, i32 } landingpad as a hook to find the gc.statepoint, while the patch directly uses a token type landingpad (http://reviews.llvm.org/D15405) to find the gc.statepoint. Reviewers: sanjoy, JosephTremoulet, pgavlin, igor-laevsky, mjacob Subscribers: reames, mjacob, sanjoy, llvm-commits Differential Revision: http://reviews.llvm.org/D15662 llvm-svn: 256443
* Move the personality function from LandingPadInst to FunctionDavid Majnemer2015-06-171-3/+3
| | | | | | | | | | | | | | | | | | | The personality routine currently lives in the LandingPadInst. This isn't desirable because: - All LandingPadInsts in the same function must have the same personality routine. This means that each LandingPadInst beyond the first has an operand which produces no additional information. - There is ongoing work to introduce EH IR constructs other than LandingPadInst. Moving the personality routine off of any one particular Instruction and onto the parent function seems a lot better than have N different places a personality function can sneak onto an exceptional function. Differential Revision: http://reviews.llvm.org/D10429 llvm-svn: 239940
* [Statepoints] Test only change. Check that statepoint lowering didn't ↵Igor Laevsky2015-06-161-0/+2
| | | | | | | | generate more than expected amount of spills. See http://reviews.llvm.org/D10402 for related discussion. llvm-svn: 239842
* [StatepointLowering] Reuse stack slots across basic blocksIgor Laevsky2015-06-101-1/+45
| | | | | | | | | | | During statepoint lowering we can sometimes avoid spilling of the value if we know that it was already spilled for previous statepoint. We were doing this by checking if incoming statepoint value was lowered into load from stack slot. This was working only in boundaries of one basic block. But instead of looking at the lowered node we can look directly at the llvm-ir value and if it was gc.relocate (or some simple modification of it) look up stack slot for it's derived pointer and reuse stack slot from it. This allows us to look across basic block boundaries. Differential Revision: http://reviews.llvm.org/D10251 llvm-svn: 239472
* [Statepoints] Support for "patchable" statepoints.Sanjoy Das2015-05-121-18/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This change adds two new parameters to the statepoint intrinsic, `i64 id` and `i32 num_patch_bytes`. `id` gets propagated to the ID field in the generated StackMap section. If the `num_patch_bytes` is non-zero then the statepoint is lowered to `num_patch_bytes` bytes of nops instead of a call (the spill and reload code remains unchanged). A non-zero `num_patch_bytes` is useful in situations where a language runtime requires complete control over how a call is lowered. This change brings statepoints one step closer to patchpoints. With some additional work (that is not part of this patch) it should be possible to get rid of `TargetOpcode::STATEPOINT` altogether. PlaceSafepoints generates `statepoint` wrappers with `id` set to `0xABCDEF00` (the old default value for the ID reported in the stackmap) and `num_patch_bytes` set to `0`. This can be made more sophisticated later. Reviewers: reames, pgavlin, swaroop.sridhar, AndyAyers Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D9546 llvm-svn: 237214
* Reverse ordering of base and derived pointer during safepoint lowering.Igor Laevsky2015-05-121-4/+4
| | | | | | | | According to the documentation in StackMap section for the safepoint we should have: "The first Location in each pair describes the base pointer for the object. The second is the derived pointer actually being relocated." But before this change we emitted them in reverse order - derived pointer first, base pointer second. llvm-svn: 237126
* Extend the statepoint intrinsic to allow statepoints to be marked as ↵Pat Gavlin2015-05-081-16/+16
| | | | | | | | | | | | | | | | | | | | | | transitions from GC-aware code to code that is not GC-aware. This changes the shape of the statepoint intrinsic from: @llvm.experimental.gc.statepoint(anyptr target, i32 # call args, i32 unused, ...call args, i32 # deopt args, ...deopt args, ...gc args) to: @llvm.experimental.gc.statepoint(anyptr target, i32 # call args, i32 flags, ...call args, i32 # transition args, ...transition args, i32 # deopt args, ...deopt args, ...gc args) This extension offers the backend the opportunity to insert (somewhat) arbitrary code to manage the transition from GC-aware code to code that is not GC-aware and back. In order to support the injection of transition code, this extension wraps the STATEPOINT ISD node generated by the usual lowering lowering with two additional nodes: GC_TRANSITION_START and GC_TRANSITION_END. The transition arguments that were passed passed to the intrinsic (if any) are lowered and provided as operands to these nodes and may be used by the backend during code generation. Eventually, the lowering of the GC_TRANSITION_{START,END} nodes should be informed by the GC strategy in use for the function containing the intrinsic call; for now, these nodes are instead replaced with no-ops. Differential Revision: http://reviews.llvm.org/D9501 llvm-svn: 236888
* [opaque pointer type] Add textual IR support for explicit type parameter to ↵David Blaikie2015-04-161-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the call instruction See r230786 and r230794 for similar changes to gep and load respectively. Call is a bit different because it often doesn't have a single explicit type - usually the type is deduced from the arguments, and just the return type is explicit. In those cases there's no need to change the IR. When that's not the case, the IR usually contains the pointer type of the first operand - but since typed pointers are going away, that representation is insufficient so I'm just stripping the "pointerness" of the explicit type away. This does make the IR a bit weird - it /sort of/ reads like the type of the first operand: "call void () %x(" but %x is actually of type "void ()*" and will eventually be just of type "ptr". But this seems not too bad and I don't think it would benefit from repeating the type ("void (), void () * %x(" and then eventually "void (), ptr %x(") as has been done with gep and load. This also has a side benefit: since the explicit type is no longer a pointer, there's no ambiguity between an explicit type and a function that returns a function pointer. Previously this case needed an explicit type (eg: a function returning a void() function was written as "call void () () * @x(" rather than "call void () * @x(" because of the ambiguity between a function returning a pointer to a void() function and a function returning void). No ambiguity means even function pointer return types can just be written alone, without writing the whole function's type. This leaves /only/ the varargs case where the explicit type is required. Given the special type syntax in call instructions, the regex-fu used for migration was a bit more involved in its own unique way (as every one of these is) so here it is. Use it in conjunction with the apply.sh script and associated find/xargs commands I've provided in rr230786 to migrate your out of tree tests. Do let me know if any of this doesn't cover your cases & we can iterate on a more general script/regexes to help others with out of tree tests. About 9 test cases couldn't be automatically migrated - half of those were functions returning function pointers, where I just had to manually delete the function argument types now that we didn't need an explicit function type there. The other half were typedefs of function types used in calls - just had to manually drop the * from those. import fileinput import sys import re pat = re.compile(r'((?:=|:|^|\s)call\s(?:[^@]*?))(\s*$|\s*(?:(?:\[\[[a-zA-Z0-9_]+\]\]|[@%](?:(")?[\\\?@a-zA-Z0-9_.]*?(?(3)"|)|{{.*}}))(?:\(|$)|undef|inttoptr|bitcast|null|asm).*$)') addrspace_end = re.compile(r"addrspace\(\d+\)\s*\*$") func_end = re.compile("(?:void.*|\)\s*)\*$") def conv(match, line): if not match or re.search(addrspace_end, match.group(1)) or not re.search(func_end, match.group(1)): return line return line[:match.start()] + match.group(1)[:match.group(1).rfind('*')].rstrip() + match.group(2) + line[match.end():] for line in sys.stdin: sys.stdout.write(conv(re.search(pat, line), line)) llvm-svn: 235145
* Require a GC strategy be specified for functions which use gc.statepointPhilip Reames2015-03-271-2/+2
| | | | | | This was discussed a while back and I left it optional for migration. Since it's been far more than the 'week or two' that was discussed, time to actually make this manditory. llvm-svn: 233357
* statepoint tests: use statepoint-example gcRamkumar Ramachandra2015-01-151-19/+19
| | | | | | | Mechanical conversion of statepoint tests to use the example-statepoint gc. llvm-svn: 226183
* [Statepoints 3/4] Statepoint infrastructure for garbage collection: ↵Philip Reames2014-12-021-0/+60
SelectionDAGBuilder This is the third patch in a small series. It contains the CodeGen support for lowering the gc.statepoint intrinsic sequences (223078) to the STATEPOINT pseudo machine instruction (223085). The change also includes the set of helper routines and classes for working with gc.statepoints, gc.relocates, and gc.results since the lowering code uses them. With this change, gc.statepoints should be functionally complete. The documentation will follow in the fourth change, and there will likely be some cleanup changes, but interested parties can start experimenting now. I'm not particularly happy with the amount of code or complexity involved with the lowering step, but at least it's fairly well isolated. The statepoint lowering code is split into it's own files and anyone not working on the statepoint support itself should be able to ignore it. During the lowering process, we currently spill aggressively to stack. This is not entirely ideal (and we have plans to do better), but it's functional, relatively straight forward, and matches closely the implementations of the patchpoint intrinsics. Most of the complexity comes from trying to keep relocated copies of values in the same stack slots across statepoints. Doing so avoids the insertion of pointless load and store instructions to reshuffle the stack. The current implementation isn't as effective as I'd like, but it is functional and 'good enough' for many common use cases. In the long term, I'd like to figure out how to integrate the statepoint lowering with the register allocator. In principal, we shouldn't need to eagerly spill at all. The register allocator should do any spilling required and the statepoint should simply record that fact. Depending on how challenging that turns out to be, we may invest in a smarter global stack slot assignment mechanism as a stop gap measure. Reviewed by: atrick, ributzka llvm-svn: 223137
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