This patch will optimize the following cases:
sub r1, r3 | sub r1, imm
cmp r3, r1 or cmp r1, r3 | cmp r1, imm
bge L1
TO
subs r1, r3
bge L1 or ble L1
If the branch instruction can use flag from "sub", then we can replace
"sub" with "subs" and eliminate the "cmp" instruction.
rdar: 10734411
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156550 91177308-0d34-0410-b5e6-96231b3b80d8
When a combine twiddles an extract_vector, care should be take to preserve
the type of the index operand. No luck extracting a reasonable testcase,
unfortunately.
rdar://11391009
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156419 91177308-0d34-0410-b5e6-96231b3b80d8
At least some of them:
%vreg1:sub_16bit = COPY %vreg2:sub_16bit; GR64:%vreg1, GR32: %vreg2
Previously, we couldn't figure out that the above copy could be
eliminated by coalescing %vreg2 with %vreg1:sub_32bit.
The new getCommonSuperRegClass() hook makes it possible.
This is not very useful yet since the unmodified part of the destination
register usually interferes with the source register. The coalescer
needs to understand sub-register interference checking first.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156334 91177308-0d34-0410-b5e6-96231b3b80d8
The getPointerRegClass() hook can return register classes that depend on
the calling convention of the current function (ptr_rc_tailcall).
So far, we have been able to infer the calling convention from the
subtarget alone, but as we add support for multiple calling conventions
per target, that no longer works.
Patch by Yiannis Tsiouris!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156328 91177308-0d34-0410-b5e6-96231b3b80d8
This will be used to determine whether it's profitable to turn a select into a
branch when the branch is likely to be predicted.
Currently enabled for everything but Atom on X86 and Cortex-A9 devices on ARM.
I'm not entirely happy with the name of this flag, suggestions welcome ;)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156233 91177308-0d34-0410-b5e6-96231b3b80d8
We want the representative register class to contain the largest
super-registers available. This makes the function less sensitive to the
register class numbering.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156220 91177308-0d34-0410-b5e6-96231b3b80d8
The masks returned by SuperRegClassIterator are computed automatically
by TableGen. This is better than depending on the manually specified
SuperRegClasses.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156147 91177308-0d34-0410-b5e6-96231b3b80d8
to catch cases like:
%reg1024<def> = MOV r1
%reg1025<def> = MOV r0
%reg1026<def> = ADD %reg1024, %reg1025
r0 = MOV %reg1026
By commuting ADD, it let coalescer eliminate all of the copies. However, there
was a bug in the heuristics where it ended up commuting the ADD in:
%reg1024<def> = MOV r0
%reg1025<def> = MOV 0
%reg1026<def> = ADD %reg1024, %reg1025
r0 = MOV %reg1026
That did no benefit but rather ensure the last MOV would not be coalesced.
rdar://11355268
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156048 91177308-0d34-0410-b5e6-96231b3b80d8
The ensures that virtual registers always belong to an allocatable class.
If your target attempts to create a vreg for an operand that has no
allocatable register subclass, you will crash quickly.
This ensures that targets define register classes as intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156046 91177308-0d34-0410-b5e6-96231b3b80d8
The TargetPassManager's default constructor wants to initialize the PassManager
to 'null'. But it's illegal to bind a null reference to a null l-value. Make the
ivar a pointer instead.
PR12468
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155902 91177308-0d34-0410-b5e6-96231b3b80d8
This time, also fix the caller of AddGlue to properly handle
incomplete chains. AddGlue had failure modes, but shamefully hid them
from its caller. It's luck ran out.
Fixes rdar://11314175: BuildSchedUnits assert.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155749 91177308-0d34-0410-b5e6-96231b3b80d8
DAGCombine strangeness may result in multiple loads from the same
offset. They both may try to glue themselves to another load. We could
insist that the redundant loads glue themselves to each other, but the
beter fix is to bail out from bad gluing at the time we detect it.
Fixes rdar://11314175: BuildSchedUnits assert.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155668 91177308-0d34-0410-b5e6-96231b3b80d8
Cross-class joins have been normal and fully supported for a while now.
With TableGen generating the getMatchingSuperRegClass() hook, they are
unlikely to cause problems again.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155552 91177308-0d34-0410-b5e6-96231b3b80d8
Remove the heuristic for disabling cross-class joins. The greedy
register allocator can handle the narrow register classes, and when it
splits a live range, it can pick a larger register class.
Benchmarks were unaffected by this change.
<rdar://problem/11302212>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155551 91177308-0d34-0410-b5e6-96231b3b80d8
The DAG builder is a convenient place to do it. Hopefully this is more
efficient than a separate traversal over the same region.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155456 91177308-0d34-0410-b5e6-96231b3b80d8
MachineInstr sequence.
This uses the new target interface for tracking register pressure
using pressure sets to model overlapping register classes and
subregisters.
RegisterPressure results can be tracked incrementally or stored at
region boundaries. Global register pressure can be deduced from local
RegisterPressure results if desired.
This is an early, somewhat untested implementation. I'm working on
testing it within the context of a register pressure reducing
MachineScheduler.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155454 91177308-0d34-0410-b5e6-96231b3b80d8
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
The X86 target is editing the selection DAG while isel is selecting
nodes following a topological ordering. When the DAG hacking triggers
CSE, nodes can be deleted and bad things happen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155257 91177308-0d34-0410-b5e6-96231b3b80d8
Now that multiple DAGUpdateListeners can be active at the same time,
ISelPosition can become a local variable in DoInstructionSelection.
We simply register an ISelUpdater with CurDAG while ISelPosition exists.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155249 91177308-0d34-0410-b5e6-96231b3b80d8
