When splitting global live ranges, it is now possible to split for
multiple destination intervals at once. Previously, we only had the main
and stack intervals.

Each edge bundle is assigned to a split candidate, and splitAroundRegion
will insert copies between the candidate intervals and the stack
interval as needed.

The multi-way splitting is used to split around compact regions when
enabled with -compact-regions. The best candidate register still gets
all the bundles it wants, but everything outside the main interval is
first split around compact regions before we create single-block
intervals.

Compact region splitting still causes some regressions, so it is not
enabled by default.

llvm-svn: 136186

llvm-svn: 136178

These copies would coalesce easily, but the resulting value would be
defined by a deleted instruction. Now we also remove the undefined value
number from the destination register.

This fixes PR10503.

llvm-svn: 136174

llvm-svn: 136156

llvm-svn: 136130

While extracting lexical scopes from machine instruction stream, work on one machine basic block at a time. 

llvm-svn: 136106

llvm-svn: 136080

When dead code elimination deletes a PHI value, the virtual register may
split into multiple connected components. In that case, revert each
component to the RS_Assign stage.

The new components are guaranteed to be smaller (the original value
numbers are distributed among the components), so this will always be
making progress. The components are now allowed to evict other live
ranges or be split again.

llvm-svn: 136034

llvm-svn: 136031

Rename TargetAsmParser to MCTargetAsmParser and TargetAsmLexer to MCTargetAsmLexer; rename createAsmLexer to createMCAsmLexer and createAsmParser to createMCAsmParser.

llvm-svn: 136027

llvm-svn: 136010

Initial implementation of 'fence' instruction, the new C++0x-style replacement for llvm.memory.barrier.

This is just a LangRef entry and reading/writing/memory representation; optimizer+codegen support coming soon.

llvm-svn: 136009

llvm-svn: 135993

MachineBlockFrequencyInfo.

llvm-svn: 135937

This mechanism already exists, but the RS_Split2 stage makes it clearer.

When live range splitting creates ranges that may not be making
progress, they are marked RS_Split2 instead of RS_New. These ranges may
be split again, but only in a way that can be proven to make progress.

For local ranges, that means they must be split into ranges used by
strictly fewer instructions.

For global ranges, region splitting is bypassed and the RS_Split2
ranges go straight to per-block splitting.

llvm-svn: 135912

The stage is used to control where a live range is going, not where it
is coming from. Live ranges created by splitting will usually be marked
RS_New, but some are marked RS_Spill to avoid wasting time trying to
split them again.

The old RS_Global and RS_Local stages are merged - they are really the
same thing for local and global live ranges.

llvm-svn: 135911

llvm-svn: 135904

llvm-svn: 135886

This fixes PR10463. A two-address instruction with an <undef> use
operand was incorrectly rewritten so the def and use no longer used the
same register, violating the tie constraint.

Fix this by always rewriting <undef> operands with the register a def
operand would use.

llvm-svn: 135885

This method computes the edge bundles that should be live when splitting
around a compact region. This is independent of interference.

The function returns false if the live range was already a compact
region, or the compact region doesn't have any live bundles - it would
be the same as splitting around basic blocks.

Compact regions are computed using the normal spill placement code. We
pretend there is interference in all live-through blocks that don't use
the live range. This removes all edges from the Hopfield network used
for spill placement, so it converges instantly.

llvm-svn: 135847

If there is no interference and no last split point, we cannot
enterIntvBefore(Stop) - that function needs a real instruction.

Use enterIntvAtEnd instead for that very easy case.

This code doesn't currently run, it is needed by multi-way splitting.

llvm-svn: 135846

A split candidate can have a null PhysReg which means that it doesn't
map to a real interference pattern. Instead, pretend that all through
blocks have interference.

This makes it possible to generate compact regions where the live range
doesn't go through blocks that don't use it. The live range will still
be live between directly connected blocks with uses.

Splitting around a compact region tends to produce a live range with a
high spill weight, so it may evict a less dense live range.

llvm-svn: 135845

This method matches addLinks - All the listed blocks are considered to
have interference, so they add a negative bias to their bundles.

This could also be done by addConstraints, but that requires building a
separate BlockConstraint array.

llvm-svn: 135844

They always report 'no interference'.

llvm-svn: 135843

llvm-svn: 135833

ConstantExpr::getGetElementPtr to use ArrayRef.

llvm-svn: 135762

ArrayRef.

llvm-svn: 135761

llvm-svn: 135742

llvm-svn: 135738

llvm-svn: 135734

llvm-svn: 135724

llvm-svn: 135714

llvm-svn: 135633

There are two ways to map a variable to its lexical scope. Lexical scope information is embedded in MDNode describing the variable. It is also available as a part of DebugLoc attached with DBG_VALUE instruction. DebugLoc attached with an instruction is less reliable in optimized code so use information embedded in the MDNode.

llvm-svn: 135629

While emitting constant value, look through derived type and use underlying basic type to determine size and signness of the constant value.

llvm-svn: 135627

There is still a bit more refactoring left to do in Targets. But we are now very
close to fixing all the layering issues in MC.

llvm-svn: 135611

llvm-svn: 135595

- Introduce JITDefault code model. This tells targets to set different default
  code model for JIT. This eliminates the ugly hack in TargetMachine where
  code model is changed after construction.

llvm-svn: 135580

TargetLoweringObjectFileImpl down to MCObjectFileInfo.

TargetAsmInfo is done to one last method. It's *almost* gone!

llvm-svn: 135569

llvm-svn: 135535