Commit Graph

18 Commits

Author SHA1 Message Date
Quentin Colombet
5074b3866a [ImplicitNullChecks] Account for implicit-defs as well when updating the liveness.
The replaced load may have implicit-defs and those defs may be used
in the block of the original load. Make sure to update the liveness
accordingly.

This is a generalization of r267817.

llvm-svn: 268412
2016-05-03 18:09:06 +00:00
Quentin Colombet
6b53c89899 [X86] Model FAULTING_LOAD_OP as a terminator and branch.
This operation may branch to the handler block and we do not want it
to happen anywhere within the basic block.
Moreover, by marking it "terminator and branch" the machine verifier
does not wrongly assume (because of AnalyzeBranch not knowing better)
the branch is analyzable. Indeed, the target was seeing only the
unconditional branch and not the faulting load op and thought it was
a simple unconditional block.
The machine verifier was complaining because of that and moreover,
other optimizations could have done wrong transformation!

In the process, simplify the representation of the handler block in
the faulting load op. Now, we directly reference the handler block
instead of using a label. This has the benefits of:
1. MC knows how to issue a label for a BB, so leave that to it.
2. Accessing the target BB from its label is painful, whereas it is
   direct from a MBB operand.

Note: The 2 bytes offset in implicit-null-check.ll comes from the
fact the unconditional jumps are not removed anymore, as the whole
terminator sequence is not analyzable anymore.

Will fix it in a subsequence commit.

llvm-svn: 268327
2016-05-02 22:58:54 +00:00
Quentin Colombet
f4848d8e0c [ImplicitNullChecks] Properly update the live-in of the block of the memory operation.
We basically replace:
HoistBB:
cond_br NullBB, NotNullBB

NullBB:
  ...

NotNullBB:
  <reg> = load

into
HoistBB
<reg> = load_faulting_op NullBB
uncond_br NotNullBB

NullBB:
  ...

NotNullBB: ## <reg> is now live-in of NotNullBB
  ...

This partially fixes the machine verifier error for
test/CodeGen/X86/implicit-null-check.ll, but it still fails because
of the implicit CFG structure.

llvm-svn: 267817
2016-04-27 23:26:40 +00:00
Derek Schuff
9f833b6097 Introduce MachineFunctionProperties and the AllVRegsAllocated property
MachineFunctionProperties represents a set of properties that a MachineFunction
can have at particular points in time. Existing examples of this idea are
MachineRegisterInfo::isSSA() and MachineRegisterInfo::tracksLiveness() which
will eventually be switched to use this mechanism.
This change introduces the AllVRegsAllocated property; i.e. the property that
all virtual registers have been allocated and there are no VReg operands
left.

With this mechanism, passes can declare that they require a particular property
to be set, or that they set or clear properties by implementing e.g.
MachineFunctionPass::getRequiredProperties(). The MachineFunctionPass base class
verifies that the requirements are met, and handles the setting and clearing
based on the delcarations. Passes can also directly query and update the current
properties of the MF if they want to have conditional behavior.

This change annotates the target-independent post-regalloc passes; future
changes will also annotate target-specific ones.

Reviewers: qcolombet, hfinkel

Differential Revision: http://reviews.llvm.org/D18421

llvm-svn: 264593
2016-03-28 17:05:30 +00:00
Chad Rosier
689669fdb4 [TII] Allow getMemOpBaseRegImmOfs() to accept negative offsets. NFC.
http://reviews.llvm.org/D17967

llvm-svn: 263021
2016-03-09 16:00:35 +00:00
Sanjoy Das
1bbbcc7ad0 [ImplicitNulls] Add some clarifying comments; NFC
llvm-svn: 253020
2015-11-13 08:14:00 +00:00
Sanjoy Das
154f32f3a8 [ImplicitNulls] Fix wrapping by breaking up a condition, NFC
llvm-svn: 252947
2015-11-12 20:51:49 +00:00
Sanjoy Das
3c4432b86c [ImplicitNull] Extract out a HazardDetector class, NFC
This will make later functional changes easier to follow.

llvm-svn: 252946
2015-11-12 20:51:44 +00:00
Chen Li
d484b66994 Introduce enum value for previously defined metadata -- make.implicit
Summary: This patch adds enum value for an existing metadata type -- make.implicit. Using preassigned enum will be helpful to get compile time type checking and avoid string construction and comparison. The patch also changes uses of make.implicit from string metadata to enum metadata. There is no functionality change.

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11698

llvm-svn: 243954
2015-08-04 04:41:34 +00:00
Sanjoy Das
8a13b0e25b [ImplicitNullChecks] Work with implicit defs.
Summary:
This change generalizes the implicit null checks pass to work with
instructions that don't have any explicit register defs.  This lets us
use X86's `cmp` against memory as faulting load instructions.

Reviewers: reames, JosephTremoulet

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11286

llvm-svn: 242703
2015-07-20 20:31:39 +00:00
Sanjoy Das
8121a95455 [ImplicitNullChecks] Fix a memory leak.
llvm-svn: 241851
2015-07-09 20:13:31 +00:00
Sanjoy Das
fefc8af84a [ImplicitNullChecks] Be smarter in picking the memory op.
Summary:
Before this change ImplicitNullChecks would only pick loads of the form:

```
   test Reg, Reg
   jz elsewhere
 fallthrough:
   movl 32(Reg), Reg2
```

but not (say)

```
   test Reg, Reg
   jz elsewhere
 fallthrough:
   inc Reg3
   movl 32(Reg), Reg2
```

This change teaches ImplicitNullChecks to look through "unrelated"
instructions like `inc Reg3` when searching for a load instruction
to convert to a trapping load.

Reviewers: atrick, JosephTremoulet, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11044

llvm-svn: 241850
2015-07-09 20:13:25 +00:00
Sanjoy Das
1208fe394b [FaultMaps] Add statistic to count the # of implicit null checks.
llvm-svn: 241521
2015-07-06 23:32:10 +00:00
Sanjoy Das
d0dd6a0ba1 [FaultMaps] Let the frontend pre-select implicit null check candidates.
Summary:
This change introduces a !make.implicit metadata that allows the
frontend to pre-select the set of explicit null checks that will be
considered for transformation into implicit null checks.

The reason for not using profiling data instead of !make.implicit is
explained in the change to `FaultMaps.rst`.

Reviewers: atrick, reames, pgavlin, JosephTremoulet

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10824

llvm-svn: 241116
2015-06-30 21:22:32 +00:00
Alexander Kornienko
f993659b8f Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)
Apparently, the style needs to be agreed upon first.

llvm-svn: 240390
2015-06-23 09:49:53 +00:00
Alexander Kornienko
40cb19d802 Fixed/added namespace ending comments using clang-tidy. NFC
The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
  -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
  llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
2015-06-19 15:57:42 +00:00
Eric Christopher
0b2dfae3ba Fix "the the" in comments.
llvm-svn: 240112
2015-06-19 01:53:21 +00:00
Sanjoy Das
cc16b02fd5 [CodeGen] Add a pass to fold null checks into nearby memory operations.
Summary:
This change adds an "ImplicitNullChecks" target dependent pass.  This
pass folds null checks into memory operation using the FAULTING_LOAD
pseudo-op introduced in previous patches.

Depends on D10197
Depends on D10199
Depends on D10200

Reviewers: reames, rnk, pgavlin, JosephTremoulet, atrick

Reviewed By: atrick

Subscribers: ab, JosephTremoulet, llvm-commits

Differential Revision: http://reviews.llvm.org/D10201

llvm-svn: 239743
2015-06-15 18:44:27 +00:00