1) Do forward copy propagation. This makes it easier to estimate the cost of the
   instruction being sunk.
2) Break critical edges on demand, including cases where the value is used by
   PHI nodes.
Critical edge splitting is not yet enabled by default.

llvm-svn: 114227

llvm-svn: 111575

llvm-svn: 111537

llvm-svn: 111531

llvm-svn: 111530

If any def of a machine-sink candidate has local uses, it's obviously not safe to sink it to a successor block. This bug has been hidden because a later check for critical-edge disable these illegal optimizations. This patch should significantly reduce the amount of time spent on checking dominator information for obviously unsafe sinking.

llvm-svn: 111450

llvm-svn: 110460

llvm-svn: 110410

ID member as the sole unique type identifier.  Clean up APIs related to this change.

llvm-svn: 110396

llvm-svn: 109045

- 2010-06-25-CoalescerSubRegDefDead.ll is the testcase for r106878.

llvm-svn: 106880

Revert r106066, "Create a more targeted fix for not sinking instructions into a range where it"... it causes bzip2 to be miscompiled by Clang.

Conflicts:

	lib/CodeGen/MachineSink.cpp

llvm-svn: 106614

llvm-svn: 106119

will conflict with another live range. The place which creates this scenerio is
the code in X86 that lowers a select instruction by splitting the MBBs. This
eliminates the need to check from the bottom up in an MBB for live pregs.

llvm-svn: 106066

llvm-svn: 105435

registers it defines then interfere with an existing preg live range.

For instance, if we had something like these machine instructions:

BB#0
  ... = imul ... EFLAGS<imp-def,dead>
  test ..., EFLAGS<imp-def>
  jcc BB#2 EFLAGS<imp-use>

BB#1
  ... ; fallthrough to BB#2

BB#2
  ... ; No code that defines EFLAGS
  jcc ... EFLAGS<imp-use>

Machine sink will come along, see that imul implicitly defines EFLAGS, but
because it's "dead", it assumes that it can move imul into BB#2. But when it
does, imul's "dead" imp-def of EFLAGS is raised from the dead (a zombie) and
messes up the condition code for the jump (and pretty much anything else which
relies upon it being correct).

The solution is to know which pregs are live going into a basic block. However,
that information isn't calculated at this point. Nor does the LiveVariables pass
take into account non-allocatable physical registers. In lieu of this, we do a
*very* conservative pass through the basic block to determine if a preg is live
coming out of it.

llvm-svn: 105387

llvm-svn: 105359

when they move instructions.

llvm-svn: 103737

MachineLoopInfo is already available when MachineSinking runs, so the check is
free.

There is no test case because it would require a critical edge into a loop, and
CodeGenPrepare splits those. This check is just to be extra careful.

llvm-svn: 101420

Sometimes it is desirable to sink instructions along a critical edge:

x = ...
if (a && b) ...
else use(x);

The 'a && b' condition creates a critical edge to the else block, but we still
want to sink the computation of x into the block. The else block is dominated by
the parent block, so we are not pushing instructions into new code paths.

llvm-svn: 101165

llvm-svn: 100455

llvm-svn: 97765

llvm-svn: 97578

into TargetOpcodes.h.  #include the new TargetOpcodes.h
into MachineInstr.  Add new inline accessors (like isPHI())
to MachineInstr, and start using them throughout the 
codebase.

llvm-svn: 95687

llvm-svn: 92593

VISIBILITY_HIDDEN removal.

llvm-svn: 85043

Chris claims we should never have visibility_hidden inside any .cpp file but
that's still not true even after this commit.

llvm-svn: 85042

llvm-svn: 84504

llvm-svn: 84503

is trivially rematerializable and integrate it into
TargetInstrInfo::isTriviallyReMaterializable. This way, all places that
need to know whether an instruction is rematerializable will get the
same answer.

This enables the useful parts of the aggressive-remat option by
default -- using AliasAnalysis to determine whether a memory location
is invariant, and removes the questionable parts -- rematting operations
with virtual register inputs that may not be live everywhere.

llvm-svn: 83687

implementations with a new MachineInstr::isInvariantLoad, which uses
MachineMemOperands and is target-independent. This brings MachineLICM
and other functionality to targets which previously lacked an
isInvariantLoad implementation.

llvm-svn: 83475

allocatable. Even if it doesn't appear to have any defs, it may latter
on after register allocation.

llvm-svn: 82834

which have no defs anywhere in the function. In particular, this fixes sinking
of instructions that reference RIP on x86-64, which is currently being modeled
as a register.

llvm-svn: 82815

and skipping the defs.

llvm-svn: 82811

upgrading a few things to use raw_ostream

llvm-svn: 79811

llvm-svn: 79755

llvm-svn: 78139

llvm-svn: 77754

1. Sinking would crash when the first instruction of a block was
   sunk due to iterator problems.
2. Instructions could be sunk to their current block, causing an
   infinite loop.

This fixes PR3968

llvm-svn: 68787

llvm-svn: 64582