It is safe if CPSR is killed or re-defined.
When we are done with the basic block, check whether CPSR is live-out.
Do not optimize away cmp if CPSR is live-out.
llvm-svn: 160090
My last checkin was apparently not the branch I intended. It was missing one change (added by chandlerc), and contained a spurious change.
llvm-svn: 159548
Use getUniqueVRegDef.
Replace a loop with existing interfaces: modifiesRegister and readsRegister.
Factor out code into inline functions and simplify the code.
llvm-svn: 159470
The TargetInstrInfo::getNumMicroOps API does not change, but soon it
will be used by MachineScheduler. Now each subtarget can specify the
number of micro-ops per itinerary class. For ARM, this is currently
always dynamic (-1), because it is used for load/store multiple which
depends on the number of register operands.
Zero is now a valid number of micro-ops. This can be used for
nop pseudo-instructions or instructions that the hardware can squash
during dispatch.
llvm-svn: 159406
More condition codes are included when deciding whether to remove cmp after
a sub instruction. Specifically, we extend from GE|LT|GT|LE to
GE|LT|GT|LE|HS|LS|HI|LO|EQ|NE. If we have "sub a, b; cmp b, a; movhs", we
should be able to replace with "sub a, b; movls".
rdar: 11725965
llvm-svn: 159166
This is a minor drive-by fix with no robust way to unit test.
As an example see neon-div.ll:
SU(16): %Q8<def> = VMOVLsv4i32 %D17, pred:14, pred:%noreg, %Q8<imp-use,kill>
val SU(1): Latency=2 Reg=%Q8
...should be latency=1
llvm-svn: 158960
Minor drive by fix to cleanup latency computation. Calling
getOperandLatency with a deliberately incorrect operand index does not
give you the latency you want.
llvm-svn: 158959
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
llvm-svn: 156599
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
llvm-svn: 156550
A MOVCCr instruction can be commuted by inverting the condition. This
can help reduce register pressure and remove unnecessary copies in some
cases.
<rdar://problem/11182914>
llvm-svn: 154033
ARM recently gained DPair, DTriple, and DQuad register classes.
Update copyPhysReg() to handle copies in these register classes.
No test case, it is difficult to make the register allocator emit the
odd copies reliably. The missing DPair copy caused a failure on
partialsums in the nightly test suite.
<rdar://problem/11147997>
llvm-svn: 153686
The arm_neon intrinsics can create virtual registers from the DPair
register class which allows both even-odd and odd-even D-register pairs.
This fixes PR12389.
llvm-svn: 153603
produces a 32-bit immediate which is consumed by the use. It tries to
fold the immediate by breaking it into two parts and fold them into the
immmediate fields of two uses. e.g
movw r2, #40885
movt r3, #46540
add r0, r0, r3
=>
add.w r0, r0, #3019898880
add.w r0, r0, #30146560
;
However, this transformation is incorrect if the user produces a flag. e.g.
movw r2, #40885
movt r3, #46540
adds r0, r0, r3
=>
add.w r0, r0, #3019898880
adds.w r0, r0, #30146560
Note the adds.w may not set the carry flag even if the original sequence
would.
rdar://11116189
llvm-svn: 153484
When an instruction only writes sub-registers, it is still necessary to
add an <imp-def> operand for the super-register. When reloading into a
virtual register, rewriting will add the operand, but when loading
directly into a virtual register, the <imp-def> operand is still
necessary.
llvm-svn: 152095
With the new composite physical registers to represent arbitrary pairs
of DPR registers, we don't need the pseudo-registers anymore. Get rid of
a bunch of them that use DPR register pairs and just use the real
instructions directly instead.
llvm-svn: 152045
MachineOperands that define part of a virtual register must have an
<undef> flag if they are not intended as read-modify-write operands.
The old trick of adding an <imp-def> operand doesn't work any longer.
Fixes PR12177.
llvm-svn: 152008
Without this hook, functions w/ a completely empty body (including no
epilogue) will cause an MCEmitter assertion failure.
For example,
define internal fastcc void @empty_function() {
unreachable
}
rdar://10947471
llvm-svn: 151673
Now that canRealignStack() understands frozen reserved registers, it is
safe to use it for aligned spill instructions.
It will only return true if the registers reserved at the beginning of
register allocation allow for dynamic stack realignment.
<rdar://problem/10625436>
llvm-svn: 147579
This patch caused a miscompilation of oggenc because a frame pointer was
suddenly needed halfway through register allocation.
<rdar://problem/10625436>
llvm-svn: 147487
Use the spill slot alignment as well as the local variable alignment to
determine when the stack needs to be realigned. This works now that the
ARM target can always realign the stack by using a base pointer.
Still respect the ARMBaseRegisterInfo::canRealignStack() function
vetoing a realigned stack. Don't use aligned spill code in that case.
llvm-svn: 146997
r0 = mov #0
r0 = moveq #1
Then the second instruction has an implicit data dependency on the first
instruction. Sadly I have yet to come up with a small test case that
demonstrate the post-ra scheduler taking advantage of this.
llvm-svn: 146583
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.
llvm-svn: 146542
