Commit Graph

28 Commits

Author SHA1 Message Date
Tim Northover 775aaeb765 Remove windows line endings introduced by r252177. NFC.
llvm-svn: 252217
2015-11-05 21:54:58 +00:00
Oleg Ranevskyy 057c5a6b2b [DebugInfo] Fix ARM/AArch64 prologue_end position. Related to D11268.
Summary:
This review is related to another review request http://reviews.llvm.org/D11268, does the same and merely fixes a couple of issues with it.

D11268 is quite old and has merge conflicts against the current trunk.
This request 
 - rebases D11268 onto the new trunk;
 - resolves the merge conflicts;
 - fixes the prologue_end tests, which do not pass due to the subprogram definitions not marked as distinct.

Reviewers: echristo, rengolin, kubabrecka

Subscribers: aemerson, rengolin, jyknight, dsanders, llvm-commits, asl

Differential Revision: http://reviews.llvm.org/D14338

llvm-svn: 252177
2015-11-05 17:50:17 +00:00
James Y Knight 5567bafe93 Remove redundant TargetFrameLowering::getFrameIndexOffset virtual
function.

This was the same as getFrameIndexReference, but without the FrameReg
output.

Differential Revision: http://reviews.llvm.org/D12042

llvm-svn: 245148
2015-08-15 02:32:35 +00:00
Matthias Braun 0256486532 PrologEpilogInserter: Rewrite API to determine callee save regsiters.
This changes TargetFrameLowering::processFunctionBeforeCalleeSavedScan():

- Rename the function to determineCalleeSaves()
- Pass a bitset of callee saved registers by reference, thus avoiding
  the function-global PhysRegUsed bitset in MachineRegisterInfo.
- Without PhysRegUsed the implementation is fine tuned to not save
  physcial registers which are only read but never modified.

Related to rdar://21539507

Differential Revision: http://reviews.llvm.org/D10909

llvm-svn: 242165
2015-07-14 17:17:13 +00:00
Quentin Colombet 61b305edfd [ShrinkWrap] Add (a simplified version) of shrink-wrapping.
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>

llvm-svn: 236507
2015-05-05 17:38:16 +00:00
Alexey Samsonov fffd56ecdf Fix undefined behavior (left shift of negative value) in SystemZ backend.
This bug is reported by UBSan.

llvm-svn: 216131
2014-08-20 21:56:43 +00:00
Eric Christopher fc6de428c8 Have MachineFunction cache a pointer to the subtarget to make lookups
shorter/easier and have the DAG use that to do the same lookup. This
can be used in the future for TargetMachine based caching lookups from
the MachineFunction easily.

Update the MIPS subtarget switching machinery to update this pointer
at the same time it runs.

llvm-svn: 214838
2014-08-05 02:39:49 +00:00
Eric Christopher d913448b38 Remove the TargetMachine forwards for TargetSubtargetInfo based
information and update all callers. No functional change.

llvm-svn: 214781
2014-08-04 21:25:23 +00:00
Eric Christopher f1bd22dfa4 Remove the use and initialization of the target machine and subtarget
from SystemZFrameLowering.

llvm-svn: 212123
2014-07-01 20:18:59 +00:00
Craig Topper 840beec2d0 Make consistent use of MCPhysReg instead of uint16_t throughout the tree.
llvm-svn: 205610
2014-04-04 05:16:06 +00:00
Rafael Espindola b1f25f1b93 Replace PROLOG_LABEL with a new CFI_INSTRUCTION.
The old system was fairly convoluted:
* A temporary label was created.
* A single PROLOG_LABEL was created with it.
* A few MCCFIInstructions were created with the same label.

The semantics were that the cfi instructions were mapped to the PROLOG_LABEL
via the temporary label. The output position was that of the PROLOG_LABEL.
The temporary label itself was used only for doing the mapping.

The new CFI_INSTRUCTION has a 1:1 mapping to MCCFIInstructions and points to
one by holding an index into the CFI instructions of this function.

I did consider removing MMI.getFrameInstructions completelly and having
CFI_INSTRUCTION own a MCCFIInstruction, but MCCFIInstructions have non
trivial constructors and destructors and are somewhat big, so the this setup
is probably better.

The net result is that we don't create temporary labels that are never used.

llvm-svn: 203204
2014-03-07 06:08:31 +00:00
Richard Sandiford 21f5d68a17 [SystemZ] Use "auto" for cast results
No functional change intended.

llvm-svn: 203106
2014-03-06 11:22:58 +00:00
Richard Sandiford 28c111ec8a [SystemZ] Use "for (auto" a bit
Just the simple cases for now.  There were a few knock-on changes of
MachineBasicBlock *s to MachineBasicBlock &s.  No functional change intended.

llvm-svn: 203105
2014-03-06 11:00:15 +00:00
Richard Sandiford c231269ff9 [SystemZ] Update namespace formatting to match current guidelines
No functional change intended.

llvm-svn: 203103
2014-03-06 10:38:30 +00:00
Benjamin Kramer b6d0bd48bd [C++11] Replace llvm::next and llvm::prior with std::next and std::prev.
Remove the old functions.

llvm-svn: 202636
2014-03-02 12:27:27 +00:00
Richard Sandiford 87a4436456 [SystemZ] Rename subregs and add subreg_h32
Use subreg_hNN and subreg_lNN for the high and low NN bits of a register.
List the low registers first, so that subreg_l32 also means the low 32
bits of a 128-bit register.

Floats are stored in the upper 32 bits of a 64-bit register, so they
should use subreg_h32 rather than subreg_l32.

No behavioral change intended.

llvm-svn: 191659
2013-09-30 10:28:35 +00:00
Richard Sandiford 709bda66b9 [SystemZ] Add support for sibling calls
This first cut is pretty conservative.  The final argument register (R6)
is call-saved, so we would need to make sure that the R6 argument to a
sibling call is the same as the R6 argument to the calling function,
which seems worth keeping as a separate patch.

Saying that integer truncations are free means that we no longer
use the extending instructions LGF and LLGF for spills in int-conv-09.ll
and int-conv-10.ll.  Instead we treat the registers as 64 bits wide and
truncate them to 32-bits where necessary.  I think it's unlikely we'd
use LGF and LLGF for spills in other situations for the same reason,
so I'm removing the tests rather than replacing them.  The associated
code is generic and applies to many more instructions than just
LGF and LLGF, so there is no corresponding code removal.

llvm-svn: 188669
2013-08-19 12:42:31 +00:00
Richard Sandiford 23943229f6 [SystemZ] Allocate a second register scavenging slot
This is another prerequisite for frame-to-frame MVC copies.
I'll commit the patch that makes use of the slot separately.

The downside of trying to test many corner cases with each of the
available addressing modes is that a fair few tests need to account
for the new frame layout.  I do still think it's useful to have all
these tests though, since it's something that wouldn't get much coverage
otherwise.

llvm-svn: 185698
2013-07-05 13:11:52 +00:00
Richard Sandiford 5dd52f8c4d [SystemZ] Clean up register scavenging code
SystemZ wants normal register scavenging slots, as close to the stack or
frame pointer as possible.  The only reason it was using custom code was
because PrologEpilogInserter assumed an x86-like layout, where the frame
pointer is at the opposite end of the frame from the stack pointer.
This meant that when frame pointer elimination was disabled,
the slots ended up being as close as possible to the incoming
stack pointer, which is the opposite of what we want on SystemZ.

This patch adds a new knob to say which layout is used and converts
SystemZ to use target-independent scavenging slots.  It's one of the pieces
needed to support frame-to-frame MVCs, where two slots might be required.

The ABI requires us to allocate 160 bytes for calls, so one approach
would be to use that area as temporary spill space instead.  It would need
some surgery to make sure that the slot isn't live across a call though.

I stuck to the "isFPCloseToIncomingSP - ..." style comment on the
"do what the surrounding code does" principle.  The FP case is already
covered by several Systemz/frame-* tests, which fail without the
PrologueEpilogueInserter change, so no new ones are needed.

No behavioural change intended.

llvm-svn: 185696
2013-07-05 12:55:00 +00:00
Richard Sandiford db39b4a212 [SystemZ] Fix caller-allocated save slot FIXME
Get rid of some old code (and associated FIXME) for handling the
caller-allocated register save area.  No behavioural change intended.

llvm-svn: 185525
2013-07-03 09:11:00 +00:00
Bill Wendling bc07a8900c Use pointers to the MCAsmInfo and MCRegInfo.
Someone may want to do something crazy, like replace these objects if they
change or something.

No functionality change intended.

llvm-svn: 184175
2013-06-18 07:20:20 +00:00
Richard Sandiford 14a4449589 [SystemZ] Rename PSW to CC
Addresses a review comment from Ulrich Weigand.  No functional change intended.

I'm not sure whether the old TODO that this patch touches still holds,
but that's something we'd get to when adding a targetted scheduling
description.

llvm-svn: 182474
2013-05-22 13:38:45 +00:00
Rafael Espindola b08d2c2db0 Remove addFrameMove.
Now that we have good testing, remove addFrameMove and create cfi
instructions directly.

llvm-svn: 182052
2013-05-16 21:02:15 +00:00
Rafael Espindola 1b09836bc3 Change getFrameMoves to return a const reference.
To add a frame now there is a dedicated addFrameMove which also takes
care of constructing the move itself.

llvm-svn: 181657
2013-05-11 02:38:11 +00:00
Ulrich Weigand 5f613dfd1f [SystemZ] Add back end
This adds the actual lib/Target/SystemZ target files necessary to
implement the SystemZ target.  Note that at this point, the target
cannot yet be built since the configure bits are missing.  Those
will be provided shortly by a follow-on patch.

This version of the patch incorporates feedback from reviews by
Chris Lattner and Anton Korobeynikov.  Thanks to all reviewers!

Patch by Richard Sandiford.

llvm-svn: 181203
2013-05-06 16:15:19 +00:00
Dan Gohman dfc96aea90 Remove the SystemZ backend.
llvm-svn: 142878
2011-10-24 23:48:32 +00:00
Jakob Stoklund Olesen 4bc5e38960 Teach frame lowering to ignore debug values after the terminators.
llvm-svn: 123399
2011-01-13 21:28:52 +00:00
Anton Korobeynikov 2f93128109 Rename TargetFrameInfo into TargetFrameLowering. Also, put couple of FIXMEs and fixes here and there.
llvm-svn: 123170
2011-01-10 12:39:04 +00:00