argpromotion and structretpromote.  Basically, when replacing
a function, they used the 'changeFunction' api which changes
the entry in the function map (and steals/reuses the callgraph
node).

This has some interesting effects: first, the problem is that it doesn't
update the "callee" edges in any callees of the function in the call graph.
Second, this covers for a major problem in all the CGSCC pass stuff, which 
is that it is completely broken when functions are deleted if they *don't*
reuse a CGN.  (there is a cute little fixme about this though :).

This patch changes the protocol that CGSCC passes must obey: now the CGSCC 
pass manager copies the SCC and preincrements its iterator to avoid passes
invalidating it.  This allows CGSCC passes to mutate the current SCC.  However
multiple passes may be run on that SCC, so if passes do this, they are now
required to *update* the SCC to be current when they return.

Other less interesting parts of this patch are that it makes passes update
the CG more directly, eliminates changeFunction, and requires clients of
replaceCallSite to specify the new callee CGN if they are changing it.

llvm-svn: 80527

is itself a bitcast.  Since we have gep(bitcast(bitcast(y))) in this
case, just wait for the two bitcasts to get zapped.  This prevents
instcombine from confusing some aliasing stuff, and allows it to
directly eliminate the load in the testcase.

llvm-svn: 80508

llvm-svn: 80507

in a few scalar xforms to simplify things.

llvm-svn: 80506

llvm-svn: 80505

llvm-svn: 80504

the new Instcombine builder.

llvm-svn: 80501

llvm-svn: 80500

workslist and is set to insert new instructions before the current one.
Convert a bunch of stuff that used to call InsertNewInstBefore over to
use it, greatly simplifying code and making it more natural.

There is still a lot more to go, but this is a good start.

llvm-svn: 80492

if the operand is not an instruction.

Simplify most uses of AddOperandsToWorkList to use AddValue and
inline it into the one remaining callsite.

llvm-svn: 80488

argument stronger typed.

llvm-svn: 80487

former looks too much like AddUsersToWorkList and keeps
confusing me.

Remove AddSoonDeadInstToWorklist and change its two callers
to do the same thing in a simpler way.

llvm-svn: 80486

into their callers.  simplify ReplaceInstUsesWith.  Make
EraseInstFromFunction only add operands to the worklist if
there aren't too many of them (this was a scalability win
for crazy programs that was only infrequently enforced).
Switch more code to using EraseInstFromFunction instead of
duplicating it inline.  Change some fcmp/icmp optimizations
to modify fcmp/icmp in place instead of creating a new one
and deleting the old one just to change the predicate.

llvm-svn: 80483

llvm-svn: 80482

llvm-svn: 80481

other places.

llvm-svn: 80478

llvm-svn: 80477

llvm-svn: 80476

does constant folding of gep's: this is already handled in
a more general way.

No functionality change.

llvm-svn: 80475

llvm-svn: 80454

llvm-svn: 80431

llvm-svn: 80429

Use MDNodes to encode debug info in llvm IR.

llvm-svn: 80406

This implements the maximum spanning tree algorithm on CFGs according to
weights given by the ProfileEstimator. This is then used to implement Optimal
Edge Profiling.

llvm-svn: 80358

llvm-svn: 80334

llvm-svn: 80327

calls into a function and if the calls bring in arrays, try to merge
them together to reduce stack size.  For example, in the testcase
we'd previously end up with 4 allocas, now we end up with 2 allocas.

As described in the comments, this is not really the ideal solution
to this problem, but it is surprisingly effective.  For example, on
176.gcc, we end up eliminating 67 arrays at "gccas" time and another
24 at "llvm-ld" time.

One piece of concern that I didn't look into: at -O0 -g with
forced inlining this will almost certainly result in worse debug
info.  I think this is acceptable though given that this is a case
of "debugging optimized code", and we don't want debug info to
prevent the optimizer from doing things anyway.

llvm-svn: 80215

llvm-svn: 80205

llvm-svn: 80204

a the list of static allocas that it inlined.

llvm-svn: 80203

llvm-svn: 80202

llvm-svn: 80201

and other code cleanups.  No functionality change.

llvm-svn: 80199

llvm-svn: 80170

llvm-svn: 80073

llvm-svn: 80058

constructors.

llvm-svn: 80049

and introduce a new Instruction::isIdenticalTo which tests for full
identity, including the SubclassOptionalData flags. Also, fix the
Instruction::clone implementations to preserve the SubclassOptionalData
flags. Finally, teach several optimizations how to handle
SubclassOptionalData correctly, given these changes.

This fixes the counterintuitive behavior of isIdenticalTo not comparing
the full value, and clone not returning an identical clone, as well as
some subtle bugs that could be caused by these.

Thanks to Nick Lewycky for reporting this, and for an initial patch!

llvm-svn: 80038

sinking code, since they are special. If the loop preheader happens
to be the entry block of a function, don't sink static allocas
out of it. This fixes PR4775.

llvm-svn: 80010

llvm-svn: 80009