patch brings numerous advantages to LLVM.  One way to look at it
is through diffstat:
 109 files changed, 3005 insertions(+), 5906 deletions(-)

Removing almost 3K lines of code is a good thing.  Other advantages
include:

1. Value::getType() is a simple load that can be CSE'd, not a mutating
   union-find operation.
2. Types a uniqued and never move once created, defining away PATypeHolder.
3. Structs can be "named" now, and their name is part of the identity that
   uniques them.  This means that the compiler doesn't merge them structurally
   which makes the IR much less confusing.
4. Now that there is no way to get a cycle in a type graph without a named
   struct type, "upreferences" go away.
5. Type refinement is completely gone, which should make LTO much MUCH faster
   in some common cases with C++ code.
6. Types are now generally immutable, so we can use "Type *" instead 
   "const Type *" everywhere.

Downsides of this patch are that it removes some functions from the C API,
so people using those will have to upgrade to (not yet added) new API.  
"LLVM 3.0" is the right time to do this.

There are still some cleanups pending after this, this patch is large enough
as-is.

llvm-svn: 134829

llvm-svn: 128507

llvm-svn: 128506

llvm-svn: 128501

different visibilities.

llvm-svn: 124650

llvm-svn: 123529

llvm-svn: 123364

1. Take a flags argument instead of a bool.  This makes
   it more clear to the reader what it is used for.
2. Add a flag that says that "remapping a value not in the
   map is ok".
3. Reimplement MapValue to share a bunch of code and be a lot
   more efficient.  For lookup failures, don't drop null values
   into the map.
4. Using the new flag a bunch of code can vaporize in LinkModules
   and LoopUnswitch, kill it.

No functionality change.

llvm-svn: 123058

llvm-svn: 122637

llvm-svn: 122636

llvm-svn: 122632

llvm-svn: 122158

llvm-svn: 122157

the buildbots.

llvm-svn: 122149

llvm-svn: 122142

llvm-svn: 122141

llvm-svn: 120298

llvm-svn: 116788

llvm-svn: 115827

fix is trying to accomplish.

This code could still use some polishing.

llvm-svn: 115759

source module *and* it must be merged (instead of simply replaced or appended
to), then merge instead of replacing or adding another global.

The ObjC __image_info section was being appended to because of this
failure. This caused a crash because the linker expects the image info section
to be a specific size.

<rdar://problem/8198537>

llvm-svn: 115753

llvm-svn: 112713

fix: add a flag to MapValue and friends which indicates whether
any module-level mappings are being made. In the common case of
inlining, no module-level mappings are needed, so MapValue doesn't
need to examine non-function-local metadata, which can be very
expensive in the case of a large module with really deep metadata
(e.g. a large C++ program compiled with -g).

This flag is a little awkward; perhaps eventually it can be moved
into the ClonedCodeInfo class.

llvm-svn: 112190

individual ...", which depends on r111922, which I am reverting.

llvm-svn: 112157

instructions, not when remapping modules.

llvm-svn: 112091

- Support the LinkerWeak*Linkage types in llvm-nm and in LinkModules.cpp.

llvm-svn: 111952

which reference GlobalValues are properly remapped.

llvm-svn: 111949

llvm-svn: 111948

which does the same thing. This eliminates redundant code and
handles MDNodes better. MDNode linking still doesn't fully
work yet though.

llvm-svn: 111941

llvm-svn: 111933

llvm-svn: 111102

llvm-svn: 111082

for creating and populating NamedMDNodes.

llvm-svn: 109061

llvm-svn: 107215

metadata types which should be marked as "weak", but which the linker will
remove upon final linkage. For example, the "objc_msgSend_fixup_alloc" symbol is
defined like this:

       .globl l_objc_msgSend_fixup_alloc
       .weak_definition l_objc_msgSend_fixup_alloc
       .section __DATA, __objc_msgrefs, coalesced
       .align 3
l_objc_msgSend_fixup_alloc:
        .quad   _objc_msgSend_fixup
        .quad   L_OBJC_METH_VAR_NAME_1

This is different from the "linker_private" linkage type, because it can't have
the metadata defined with ".weak_definition".

llvm-svn: 107205

methods to try to have the type predicates be more logically positioned.

llvm-svn: 96349

llvm-svn: 95468

Need to recurse for all operands of function-local metadata; and handle Instructions (which map to themselves)

llvm-svn: 94691

llvm-svn: 94650

llvm-svn: 94632