Tail duplication produces lots of identical phi nodes in different basic
blocks. Teach PHIElimination to reuse the join registers when lowering a phi
node that is identical to an already lowered node. This saves virtual
registers, and more importantly it avoids creating copies the the coalescer
doesn't know how to eliminate.

Teach LiveIntervalAnalysis about the phi joins with multiple uses.

This patch significantly reduces code size produced by -pre-regalloc-taildup.

llvm-svn: 91549

Patch by Howard Hinnant!

llvm-svn: 90365

We want LiveVariables clients to use methods rather than accessing the
getVarInfo data structure directly. That way it will be possible to change the
LiveVariables representation.

llvm-svn: 90240

When splitting a critical edge, the registers live through the edge are:

- Used in a PHI instruction, or
- Live out from the predecessor, and
- Live in to the successor.

This allows the coalescer to eliminate even more phi joins.

llvm-svn: 89530

critical edges in PHIElimination.

This has a huge impact on regalloc performance, and we recover almost all of
the 10% compile time regression that edge splitting introduced.

llvm-svn: 89381

when LiveVariables is available.

The -split-phi-edges is now gone, and so is the hack to disable it when using
the local register allocator. The PHIElimination pass no longer has
LiveVariables as a prerequisite - that is what broke the local allocator.
Instead we do critical edge splitting when possible - that is when
LiveVariables is available.

llvm-svn: 89213

llvm-svn: 89167

llvm-svn: 89142

llvm-svn: 89139

The local register allocator doesn't like it when LiveVariables is run.
We should also disable edge splitting under -O0, but that has to wait a bit.

llvm-svn: 89125

llvm-svn: 89082

llvm-svn: 89021

Fix for the original bug in PR5495 - Look at uses as well as defs when determining the PHI-copy insert point.

- Patch by Andrew Canis!

llvm-svn: 88880

When splitting an edge after a machine basic block with fall-through, we
forgot to insert a jump instruction. Fix this by calling updateTerminator() on
the fall-through block when relevant.

Also be more precise in PHIElimination::isLiveIn.

llvm-svn: 88728

llvm-svn: 88727

The BasicBlock associated with a MachineBasicBlock does not necessarily
correspond to the code in the MBB.

Don't insert a new IR BasicBlock when splitting critical edges. We are not
supposed to modify the IR during codegen, and we should be able to do just
fine with a NULL BB.

llvm-svn: 88707

llvm-svn: 87024

- Edges are split before any phis are eliminated, so the code is SSA.

- Create a proper IR BasicBlock for the split edges.

- LiveVariables::addNewBlock now has same syntax as
  MachineDominatorTree::addNewBlock. Algorithm calculates predecessor live-out
  set rather than successor live-in set.

This feature still causes some miscompilations.

llvm-svn: 86867

Critical edges leading to a PHI node are split when the PHI source variable is
live out from the predecessor block. This help the coalescer eliminate more
PHI joins.

llvm-svn: 86725

Clean up some whitespace.
No functional changes.

llvm-svn: 86724

llvm-svn: 77754

llvm-svn: 76865

llvm-svn: 76849

llvm-svn: 76688

llvm-svn: 74925

 previous cmp; a copy can not be inserted here if the copy insn also has
 side effects. We don't have access to the attributes of copy insn here;
 so just play safe by finding a safe locations for branch terminators.

llvm-svn: 74898

entries as there are basic blocks in the function.  LiveVariables::getVarInfo
creates a VarInfo struct for every register in the function, leading to
quadratic space use.  This patch changes the BitVector to a SparseBitVector,
which doesn't help the worst-case memory use but does reduce the actual use in
very long functions with short-lived variables.

llvm-svn: 72426

llvm-svn: 72411

(which produces "call L_f$stub" rather than "call f").

llvm-svn: 67079

U    test/CodeGen/X86/2009-03-13-PHIElimBug.ll
D    test/CodeGen/X86/2009-03-16-PHIElimInLPad.ll
U    lib/CodeGen/PHIElimination.cpp

r67049 was causing this failure:

Running /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/dg.exp ...
FAIL: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/2009-03-13-PHIElimBug.ll for PR3784
Failed with exit(1) at line 1
while running:  llvm-as < /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/2009-03-13-PHIElimBug.ll |  llc -march=x86 | /usr/bin/grep -A 2 {call f} | /usr/bin/grep movl
child process exited abnormally

llvm-svn: 67051

how invokes are set up.  The fix could be disturbed by
register copies coming after the EH_LABEL, and also didn't
behave quite right when it was the invoke result that
was used in a phi node.  Also (see new testcase) fix
another phi elimination bug while there: register copies
in the landing pad need to come after the EH_LABEL, because
that's where execution branches to when unwinding.  If they
come before the EH_LABEL then they will never be executed...
Also tweak the original testcase so it doesn't use a no-longer
existing counter.
The accumulated phi elimination changes fix two of seven Ada
testsuite failures that turned up after landing pad critical
edge splitting was turned off.  So there's probably more to come.

llvm-svn: 67049

Fix PR3784: If the source of a phi comes from a bb ended with an invoke, make sure the copy is inserted before the try range (unless it's used as an input to the invoke, then insert it after the last use), not at the end of the bb.

Also re-apply r66140 which was disabled as a workaround.

llvm-svn: 66976

llvm-svn: 63599

llvm-svn: 63198

llvm-svn: 55779

MachineMemOperands. The pools are owned by MachineFunctions.

This drastically reduces the number of calls to malloc/free made
during the "Emit" phase of scheduling, as well as later phases
in CodeGen. Combined with other changes, this speeds up the
"instruction selection" phase of CodeGen by 10% in some cases.

llvm-svn: 53212

- Remove calls to copyKillDeadInfo which is an N^2 function. Instead, propagate kill / dead markers as new instructions are constructed in foldMemoryOperand, convertToThressAddress, etc.
- Also remove LiveVariables::instructionChanged, etc. Replace all calls with cheaper calls which update VarInfo kill list.

llvm-svn: 53097

llvm-svn: 52479

address of the PassInfo directly instead of calling getPassInfo.
This eliminates a bunch of dynamic initializations of static data.

Also, fold RegisterPassBase into PassInfo, make a bunch of its
data members const, and rearrange some code to initialize data
members in constructors instead of using setter member functions.

llvm-svn: 51022

several things that were neither in an anonymous namespace nor static
but not intended to be global.

llvm-svn: 51017