Commit Graph

215 Commits

Author SHA1 Message Date
Preston Gurd
6a8c7bf8e7 This patch fixes a problem which arose when using the Post-RA scheduler
on X86 Atom. Some of our tests failed because the tail merging part of
the BranchFolding pass was creating new basic blocks which did not
contain live-in information. When the anti-dependency code in the Post-RA
scheduler ran, it would sometimes rename the register containing
the function return value because the fact that the return value was
live-in to the subsequent block had been lost. To fix this, it is necessary
to run the RegisterScavenging code in the BranchFolding pass.

This patch makes sure that the register scavenging code is invoked
in the X86 subtarget only when post-RA scheduling is being done.
Post RA scheduling in the X86 subtarget is only done for Atom.

This patch adds a new function to the TargetRegisterClass to control
whether or not live-ins should be preserved during branch folding.
This is necessary in order for the anti-dependency optimizations done
during the PostRASchedulerList pass to work properly when doing
Post-RA scheduling for the X86 in general and for the Intel Atom in particular.

The patch adds and invokes the new function trackLivenessAfterRegAlloc()
instead of using the existing requiresRegisterScavenging().
It changes BranchFolding.cpp to call trackLivenessAfterRegAlloc() instead of
requiresRegisterScavenging(). It changes the all the targets that
implemented requiresRegisterScavenging() to also implement
trackLivenessAfterRegAlloc().  

It adds an assertion in the Post RA scheduler to make sure that post RA
liveness information is available when it is needed.

It changes the X86 break-anti-dependencies test to use –mcpu=atom, in order
to avoid running into the added assertion.

Finally, this patch restores the use of anti-dependency checking
(which was turned off temporarily for the 3.1 release) for
Intel Atom in the Post RA scheduler.

Patch by Andy Zhang!

Thanks to Jakob and Anton for their reviews.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155395 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-23 21:39:35 +00:00
Jakob Stoklund Olesen
80799fbe3c Branch folding may invalidate liveness.
Branch folding can use a register scavenger to update liveness
information when required. Don't do that if liveness information is
already invalid.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153517 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-27 17:06:09 +00:00
Bill Wendling
5b2749abf5 Where the BranchFolding pass removes a branch then adds another better branch,
the DebugLoc information can be maintained throughout by grabbing the DebugLoc
before the RemoveBranch and then passing the result to the InsertBranch.
Patch by Andrew Stanford-Jason!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152212 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-07 08:49:42 +00:00
Craig Topper
9ebfbf8b9f Convert more GenRegisterInfo tables from unsigned to uint16_t to reduce static data size.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152016 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-05 05:37:41 +00:00
Craig Topper
e4fd907e72 Use uint16_t to store register overlaps to reduce static data.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152001 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-04 10:43:23 +00:00
Chad Rosier
90f20044ad Remove extra semi-colons.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151169 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-22 17:25:00 +00:00
Jakob Stoklund Olesen
a230262791 Handle register masks in branch folding.
Don't attempt to move instructions with regmask operands. They are most
likely calls anyway.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150634 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-15 23:42:54 +00:00
Andrew Trick
61f1e3db43 Move pass configuration out of pass constructors: BranchFolderPass
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150095 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-08 21:22:48 +00:00
Andrew Trick
1df91b0e54 whitespace
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150094 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-08 21:22:43 +00:00
David Blaikie
4d6ccb5f68 More dead code removal (using -Wunreachable-code)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148578 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-20 21:51:11 +00:00
Evan Cheng
c16c25fbc3 When hoisting common code, watch out for uses which are marked "kill". If the
killed registers are needed below the insertion point, then unset the kill
marker.

Sorry I'm not able to find a reduced test case.

rdar://10660944


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148043 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-12 20:31:24 +00:00
Evan Cheng
70017fb01b Revert part of r147716. Looks like x87 instructions kill markers are all messed
up so branch folding pass can't use the scavenger. :-(  This doesn't breaks
anything currently. It just means targets which do not carefully update kill
markers cannot run post-ra scheduler (not new, it has always been the case).

We should fix this at some point since it's really hacky.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147719 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-07 03:35:48 +00:00
Evan Cheng
977679d603 Added a late machine instruction copy propagation pass. This catches
opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
        movl    %eax, %ecx
        movl    %ecx, %eax
        ret

The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)

This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.

rdar://10428165
rdar://10640363



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147716 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-07 03:02:36 +00:00
Evan Cheng
ddfd1377d2 - Add MachineInstrBundle.h and MachineInstrBundle.cpp. This includes a function
to finalize MI bundles (i.e. add BUNDLE instruction and computing register def
  and use lists of the BUNDLE instruction) and a pass to unpack bundles.
- Teach more of MachineBasic and MachineInstr methods to be bundle aware.
- Switch Thumb2 IT block to MI bundles and delete the hazard recognizer hack to
  prevent IT blocks from being broken apart.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146542 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-14 02:11:42 +00:00
Evan Cheng
5a96b3dad2 Add bundle aware API for querying instruction properties and switch the code
generator to it. For non-bundle instructions, these behave exactly the same
as the MC layer API.

For properties like mayLoad / mayStore, look into the bundle and if any of the
bundled instructions has the property it would return true.
For properties like isPredicable, only return true if *all* of the bundled
instructions have the property.
For properties like canFoldAsLoad, isCompare, conservatively return false for
bundles.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146026 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-07 07:15:52 +00:00
Bill Wendling
a823e3d42c Reapply r142920 with fix:
An MBB which branches to an EH landing pad shouldn't be considered for tail merging.

In SjLj EH, the jump to the landing pad is not done explicitly through a branch
statement. The EH landing pad is added as a successor to the throwing
BB. Because of that however, the branch folding pass could mistakenly think that
it could merge the throwing BB with another BB. This isn't safe to do.
<rdar://problem/10334833>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143001 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-26 01:10:25 +00:00
Duncan Sands
51583ce4b6 Revert commit 142891. Takumi bisected the tablegen miscompiles
down to this commit.  Original commit message:

An MBB which branches to an EH landing pad shouldn't be considered for tail merging.

In SjLj EH, the jump to the landing pad is not done explicitly through a branch
statement. The EH landing pad is added as a successor to the throwing
BB. Because of that however, the branch folding pass could mistakenly think that
it could merge the throwing BB with another BB. This isn't safe to do.
<rdar://problem/10334833>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142920 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-25 12:30:22 +00:00
Bill Wendling
86ed4089e3 An MBB which branches to an EH landing pad shouldn't be considered for tail merging.
In SjLj EH, the jump to the landing pad is not done explicitly through a branch
statement. The EH landing pad is added as a successor to the throwing
BB. Because of that however, the branch folding pass could mistakenly think that
it could merge the throwing BB with another BB. This isn't safe to do.
<rdar://problem/10334833>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142891 91177308-0d34-0410-b5e6-96231b3b80d8
2011-10-25 00:54:05 +00:00
Jakob Stoklund Olesen
54cfeda745 Fix liveness computations in BranchFolding.
The old code would look at kills and defs in one pass over the
instruction operands, causing problems with this code:

  %R0<def>, %CPSR<def,dead> = tLSLri %R5<kill>, 2, pred:14, pred:%noreg
  %R0<def>, %CPSR<def,dead> = tADDrr %R4<kill>, %R0<kill>, pred:14, %pred:%noreg

The last instruction kills and redefines %R0, so it is still live after
the instruction.

This caused a register scavenger crash when compiling 483.xalancbmk for
armv6. I am not including a test case because it requires too much bad
luck to expose this old bug.

First you need to convince the register allocator to use %R0 twice on
the tADDrr instruction, then you have to convince BranchFolding to do
something that causes it to run the register scavenger on he bad block.

<rdar://problem/9898200>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136973 91177308-0d34-0410-b5e6-96231b3b80d8
2011-08-05 18:47:07 +00:00
Eli Friedman
a38cfb2fce When tail-merging multiple blocks, make sure to correctly update the live-in list on the merged block to correctly account for the live-outs of all the predecessors. They might not be the same in all cases (the testcase I have involves a PHI node where one of the operands is an IMPLICIT_DEF).
Unfortunately, the testcase I have is large and confidential, so I don't have a test to commit at the moment; I'll see if I can come up with something smaller where this issue reproduces.

<rdar://problem/9716278>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134565 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-06 23:41:48 +00:00
Evan Cheng
e837dead3c - Rename TargetInstrDesc, TargetOperandInfo to MCInstrDesc and MCOperandInfo and
sink them into MC layer.
- Added MCInstrInfo, which captures the tablegen generated static data. Chang
TargetInstrInfo so it's based off MCInstrInfo.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134021 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-28 19:10:37 +00:00
Rafael Espindola
f924dea8dd Add 132986 back, but avoid non-determinism if a bb address gets reused.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132995 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-14 15:31:54 +00:00
Rafael Espindola
7a07083c25 revert 132986 to see if the bots go green.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132988 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-14 12:48:26 +00:00
Rafael Espindola
3a42565ccb Make the threshold used by branch folding softer. Before we would get a
sharp all or nothing transition when one extra predecessor was added. Now
we still test first ones for merging.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132974 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-14 04:41:17 +00:00
Devang Patel
95ba669e09 Add comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132149 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-26 21:49:28 +00:00
Devang Patel
785badb83e During branch folding avoid inserting redundant DBG_VALUE machine instructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132148 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-26 21:47:59 +00:00
Evan Cheng
6175e03825 Update comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131258 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-12 22:35:48 +00:00
Evan Cheng
7139d35165 Re-enable branchfolding common code hoisting optimization. Fixed a liveness test bug and also taught it to update liveins.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131241 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-12 20:30:01 +00:00
Evan Cheng
30adced41b Temporarily disable the transformation. It's breaking 186.crafty in some configuration.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131235 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-12 18:44:58 +00:00
Evan Cheng
cbc988be22 Re-commit 131172 with fix. MachineInstr identity checks should check dead
markers. In some cases a register def is dead on one path, but not on
another.

This is passing Clang self-hosting.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131214 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-12 00:56:58 +00:00
Rafael Espindola
41cdc16e73 Revert 131172 as it is causing clang to miscompile itself. I will try
to provide a reduced testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131176 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-11 03:27:17 +00:00
Evan Cheng
7e20a574eb Add a late optimization to BranchFolding that hoist common instruction sequences
at the start of basic blocks to their common predecessor. It's actually quite
common (e.g. about 50 times in JM/lencod) and has shown to be a nice code size
benefit. e.g.

        pushq   %rax
        testl   %edi, %edi
        jne     LBB0_2
## BB#1:
        xorb    %al, %al
        popq    %rdx
        ret
LBB0_2:
        xorb    %al, %al
        callq   _foo
        popq    %rdx
        ret

=>

        pushq   %rax
        xorb    %al, %al
        testl   %edi, %edi
        je      LBB0_2
## BB#1:
        callq   _foo
LBB0_2:
        popq    %rdx
        ret

rdar://9145558


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131172 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-11 01:03:01 +00:00
Bill Wendling
d3dbd5f5cd Branch folding is folding a landing pad into a regular BB.
An exception is thrown via a call to _cxa_throw, which we don't expect to
return. Therefore, the "true" part of the invoke goes to a BB that has
'unreachable' as its only instruction. This is lowered into an empty MachineBB.
The landing pad for this invoke, however, is directly after the "true" MBB.
When the empty MBB is removed, the landing pad is directly below the BB with the
invoke call. The unconditional branch is removed and then the two blocks are
merged together.

The testcase is too big for a regression test.
<rdar://problem/9305728>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129965 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-22 01:07:09 +00:00
Evan Cheng
cf13af6fde Add more debugging output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126158 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-21 23:39:48 +00:00
Owen Anderson
90c579de5a Reapply r110396, with fixes to appease the Linux buildbot gods.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110460 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-06 18:33:48 +00:00
Owen Anderson
1f74590e9d Revert r110396 to fix buildbots.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110410 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-06 00:23:35 +00:00
Owen Anderson
9ccaf53ada Don't use PassInfo* as a type identifier for passes. Instead, use the address of the static
ID member as the sole unique type identifier.  Clean up APIs related to this change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110396 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-05 23:42:04 +00:00
Evan Cheng
4d54e5b2dd Tail merging pass shall not break up IT blocks. rdar://8115404
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106517 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-22 01:18:16 +00:00
Evan Cheng
86050dc8cc Allow ARM if-converter to be run after post allocation scheduling.
- This fixed a number of bugs in if-converter, tail merging, and post-allocation
  scheduler. If-converter now runs branch folding / tail merging first to
  maximize if-conversion opportunities.
- Also changed the t2IT instruction slightly. It now defines the ITSTATE
  register which is read by instructions in the IT block.
- Added Thumb2 specific hazard recognizer to ensure the scheduler doesn't
  change the instruction ordering in the IT block (since IT mask has been
  finalized). It also ensures no other instructions can be scheduled between
  instructions in the IT block.

This is not yet enabled.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106344 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-18 23:09:54 +00:00
Stuart Hastings
3bf9125933 Add a DebugLoc parameter to TargetInstrInfo::InsertBranch(). This
addresses a longstanding deficiency noted in many FIXMEs scattered
across all the targets.

This effectively moves the problem up one level, replacing eleven
FIXMEs in the targets with eight FIXMEs in CodeGen, plus one path
through FastISel where we actually supply a DebugLoc, fixing Radar
7421831.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106243 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-17 22:43:56 +00:00
Dan Gohman
30fc5bbfd1 Fix a bug which prevented tail merging of return instructions in
beneficial cases. See the changes in test/CodeGen/X86/tail-opts.ll and
test/CodeGen/ARM/ifcvt2.ll for details.

The fix is to change HashEndOfMBB to hash at most one instruction,
instead of trying to apply heuristics about when it will be profitable to
consider more than one instruction. The regular tail-merging heuristics
are already prepared to handle the same cases, and they're more precise.

Also, make test/CodeGen/ARM/ifcvt5.ll and
test/CodeGen/Thumb2/thumb2-branch.ll slightly more complex so that they
continue to test what they're intended to test.

And, this eliminates the problem in
test/CodeGen/Thumb2/2009-10-15-ITBlockBranch.ll, the testcase from
PR5204. Update it accordingly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102907 91177308-0d34-0410-b5e6-96231b3b80d8
2010-05-03 14:35:47 +00:00
Dale Johannesen
93d6a7e9c2 Teach AnalyzeBranch, RemoveBranch and the branch
folder to be tolerant of debug info following the
branch(es) at the end of a block.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100168 91177308-0d34-0410-b5e6-96231b3b80d8
2010-04-02 01:38:09 +00:00
Bob Wilson
80d23705e6 Stop trying to merge identical jump tables. This had been inadvertently
disabled for several months (since svn r88806) and no one noticed.  My fix
for pr6543 yesterday reenabled it, but broke the ARM port's code for using
TBB/TBH.  Rather than adding a target hook to disable merging for Thumb2 only,
I'm just taking this out.  It is not common to have identical jump tables,
the code we used to merge them was O(N^2), and it only helps code size, not
performance.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98977 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-19 19:05:41 +00:00
Bob Wilson
a1bdfc3c7f Remove a check that can no longer be true, after r84803.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98694 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-16 23:40:32 +00:00
Chris Lattner
18589de9b1 eliminate InvalidateLabel and LabelIDList from MMI and replace
them with a counter.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98462 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-14 02:24:55 +00:00
Dale Johannesen
2cd9ffef6e Fix another place where DEBUG_VALUE affected codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98181 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 19:57:56 +00:00
Dale Johannesen
c5cf227f3d This survived a bootstrap, so let's try 98104 again.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98137 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 05:45:47 +00:00
Dale Johannesen
7dda453410 Speculatively revert 98104; could be what's causing crashes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98108 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 00:11:34 +00:00
Dale Johannesen
7f876967c0 Ever more complicated DEBUG_VALUE fixes for branch folding.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98104 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-09 23:52:37 +00:00
Dale Johannesen
84839daa59 Fix dbg value handling in tail merging.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97938 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-08 05:38:13 +00:00