If there are no positive nodes, the algorithm can be aborted early.

llvm-svn: 129021

This will allow us to abort the algorithm early if it is determined to be futile.

llvm-svn: 129020

llvm-svn: 128986

About 90% of the relevant blocks are live-through without uses, and the only
information required about them is their number. This saves memory and enables
later optimizations that need to look at only the use-blocks.

llvm-svn: 128985

llvm-svn: 128963

llvm-svn: 128962

Treat the landing pad as a normal successor when that happens.

llvm-svn: 128961

llvm-svn: 128947

llvm-svn: 128935

llvm-svn: 128929

of a basic block.

llvm-svn: 128925

When dead code elimination removes all but one use, try to fold the single def into the remaining use.

Rematerialization can leave single-use loads behind that we might as well fold whenever possible.

llvm-svn: 128918

llvm-svn: 128914

There can be multiple defs for a single virtual register when they are defining
sub-registers.

The missing <dead> flag was stopping the inline spiller from eliminating dead
code after rematerialization.

llvm-svn: 128888

llvm-svn: 128887

This allows us to always keep the smaller slot for an instruction which is what
we want when a register has early clobber defines.

Drop the UsingInstrs set and the UsingBlocks map. They are no longer needed.

llvm-svn: 128886

llvm-svn: 128875

inlined path for the common case.

Most basic blocks don't contain a call that may throw, so the last split point
os simply the first terminator.

llvm-svn: 128874

It needed to be moved closer to the setjmp statement, because the code directly
after the setjmp needs to know about values that are on the stack. Also, the
'bitcast' of the function context was causing a dead load. This wouldn't be too
horrible, except that at -O0 it wasn't optimized out, and because it wasn't
using the correct base pointer (if there is a VLA), it would try to access a
value from a garbage address.
<rdar://problem/9130540>

llvm-svn: 128873

llvm-svn: 128868

When a virtual register has a single value that is defined as a copy of a
reserved register, permit that copy to be joined. These virtual register are
usually copies of the stack pointer:

  %vreg75<def> = COPY %ESP; GR32:%vreg75
  MOV32mr %vreg75, 1, %noreg, 0, %noreg, %vreg74<kill>
  MOV32mi %vreg75, 1, %noreg, 8, %noreg, 0
  MOV32mi %vreg75<kill>, 1, %noreg, 4, %noreg, 0
  CALLpcrel32 ...

Coalescing these virtual registers early decreases register pressure.
Previously, they were coalesced by RALinScan::attemptTrivialCoalescing after
register allocation was completed.

The lower register pressure causes the mcinst-lowering-cmp0.ll test case to fail
because it depends on linear scan spilling a particular register.

I am deleting 2008-08-05-SpillerBug.ll because it is counting the number of
instructions emitted, and its revision history shows the 'correct' count being
edited many times.

llvm-svn: 128845

llvm-svn: 128844

llvm-svn: 128821

llvm-svn: 128820

llvm-svn: 128765

When the greedy register allocator is splitting multiple global live ranges, it
tends to look at the same interference data many times. The InterferenceCache
class caches queries for unaltered LiveIntervalUnions.

llvm-svn: 128764

This is more compact and faster than using DenseMap.

llvm-svn: 128763

transformations in target-specific DAG combines without causing DAGCombiner to
delete the same node twice. If you know of a better way to avoid this (see my
next patch for an example), please let me know.

llvm-svn: 128758

llvm-svn: 128730

Assign node order numbers to results of call instruction lowering. This should improve src line debug info when sdisel is used. rdar://9199118

llvm-svn: 128728

rdar://8911343

llvm-svn: 128696

It is using a trivial rewriter that doesn't know how to insert spill code
requested by the standard spiller.

llvm-svn: 128688

Turn them into noop KILL instructions instead. This lets the scavenger know when
super-registers are killed and defined.

llvm-svn: 128645

llvm-svn: 128643

This way, shrinkToUses() will ignore the instruction that is about to be
deleted, and we avoid leaving invalid live ranges that SplitKit doesn't like.

Fix a misunderstanding in MachineVerifier about <def,undef> operands. The
<undef> flag is valid on def operands where it has the same meaning as <undef>
on a use operand. It only applies to sub-register defines which also read the
full register.

llvm-svn: 128642

llvm-svn: 128639

llvm-svn: 128634

We don't expect the real "powf()" on some hosts (and powf() would be available on other hosts).
For consistency, std::pow(double,double) may be called instead.
Or, precision issue might attack us, to see unstable regalloc and stack coloring.

llvm-svn: 128629

The rematerialized instruction may require a more constrained register class
than the register being spilled. In the test case, the spilled register has been
inflated to the DPR register class, but we are rematerializing a load of the
ssub_0 sub-register which only exists for DPR_VFP2 registers.

The register class is reinflated after spilling, so the conservative choice is
only temporary.

llvm-svn: 128610

The rewriter can keep track of multiple stack slots in the same register if they
happen to have the same value. When an instruction modifies a stack slot by
defining a register that is mapped to a stack slot, other stack slots in that
register are no longer valid.

This is a very rare problem, and I don't have a simple test case. I get the
impression that VirtRegRewriter knows it is about to be deleted, inventing a
last opaque problem.

<rdar://problem/9204040>

llvm-svn: 128562