instruction around, reducing work.

Greatly simplify handling of debug instructions.  There is no need to
build up a vector of them and then move them into the one predecessor
if we're processing a block.  Instead just rescan the block and *copy*
them into the pred.  If a block gets merged into multiple preds, this
will retain more debug info.

llvm-svn: 129502

llvm-svn: 129319

llvm-svn: 129271

llvm-svn: 129114

llvm-svn: 129078

llvm-svn: 129041

llvm-svn: 129035

llvm-commits.  (Not sure why it only breaks on Windows; maybe it has
something to do with the iterator representation...)

llvm-svn: 128802

after the given instruction; make sure to handle that case correctly.
(It's difficult to trigger; the included testcase involves a dead 
block, but I don't think that's a requirement.) 

While I'm here, get rid of the unnecessary warning about
SimplifyInstructionsInBlock, since it should work correctly as far as I know.

llvm-svn: 128782

PHINode::Create() giving the (known or expected) number of operands.

llvm-svn: 128537

llvm-svn: 128535

llvm-svn: 128030

If an AllocaInst referred by DbgDeclareInst is used by a LoadInst then the LoadInst should also get a corresponding llvm.dbg.value intrinsic.

llvm-svn: 127924

llvm-svn: 127923

llvm-svn: 127922

This is done by lowering dbg.declare intrinsic into dbg.value intrinsic.
Radar 9143931.

llvm-svn: 127834

llvm-svn: 127832

llvm-svn: 127684

llvm-svn: 127674

of pointers in an std::map.

llvm-svn: 127650

reachable uses, but there still might be uses in dead blocks.  Use the
standard solution of replacing all the uses with undef.  This is
a rare case because it's very sensitive to phase ordering in SimplifyCFG.

llvm-svn: 127299

Avoid colliding with the sentinels, hopefully unbreaking
llvm-gcc-x86_64-linux-selfhost.

llvm-svn: 126982

Based on a patch by Alistair Lynn.

llvm-svn: 126647

Yes, there are other types than i8* and GEPs on them can produce an add+multiply.
We don't consider that cheap enough to be speculatively executed.

llvm-svn: 126481

llvm-svn: 126452

llvm-svn: 126445

llvm-svn: 126398

itself without going via a phi node then we could return false here in
spite of making a change.  Also, tweak the comment because this method
can (and always could) return true without deleting the original phi node.
For example, if the phi node was used by a read-only invoke instruction
which is used by another phi node phi2 which is only used by and only uses
the invoke, then phi2 would be deleted but not the invoke instruction and
not the original phi node.

llvm-svn: 126129

should be that if the phi is used by a side-effect free instruction with
no uses then the phi and the instruction now get zapped (checked by the
unittest).

llvm-svn: 126124

test for that. With this change, test/CodeGen/X86/codegen-dce.ll no longer finds
any instructions to DCE, so delete the test.

Also renamed J and JP to I and IP in RecursivelyDeleteDeadPHINode.

llvm-svn: 126088

by Andrew Clinton!

llvm-svn: 126077

This is part of a futile attempt to not "break" bizzaro
code like this:

 l1:
  printf("l1: %p\n", &&l1);
  ++x;

  if( x < 3 ) goto l1;


Previously we'd fold &&l1 to 1, which is fine per our semantics
but not helpful to the user.

llvm-svn: 125827

llvm-svn: 125317

SimplifyCFG: Track the number of used icmps when turning a icmp chain into a switch. If we used only one icmp, don't turn it into a switch.

Also prevent the switch-to-icmp transform from creating identity adds, noticed by Marius Wachtler.

llvm-svn: 125056

SimplifyCFG: Also transform switches that represent a range comparison but are not sorted into sub+icmp.

This transforms another 1000 switches in gcc.c.

llvm-svn: 124826

This makes the job of the later optzn passes easier, allowing the vast amount of
icmp transforms to chew on it.

We transform 840 switches in gcc.c, leading to a 16k byte shrink of the resulting
binary on i386-linux.

The testcase from README.txt now compiles into
  decl  %edi
  cmpl  $3, %edi
  sbbl  %eax, %eax
  andl  $1, %eax
  ret

llvm-svn: 124724

llvm-svn: 124526

llvm-svn: 124522

Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand.

llvm-svn: 124518

llvm-svn: 124478