xor R, R is a common and valid idiom for zeroing a register, for example.

llvm-svn: 75571

llvm-svn: 75539

(I think it's reasonably clear that we want to have a canonical form for 
constructs like this; if anyone thinks that a select is not the best 
canonical form, please tell me.)

llvm-svn: 75531

llvm-svn: 75528

using the Curiously Recurring Template Pattern with LoopBase.

This will help further refactoring, and future functionality for
Loop. Also, Headers can now foward-declare Loop, instead of pulling
in LoopInfo.h or doing tricks.

llvm-svn: 75519

the changes are allowed by not calling this function for bitcasts.  
The Instruction::AShr case is dead because 
SimplifyDemandedInstructionBits handles that case.

llvm-svn: 75514

llvm-svn: 75499

llvm-svn: 75497

bitcasts will always be eliminated anyway.

llvm-svn: 75495

Begin the painful process of tearing apart the rat'ss nest that is Constants.cpp and ConstantFold.cpp.
This involves temporarily hard wiring some parts to use the global context.  This isn't ideal, but it's
the only way I could figure out to make this process vaguely incremental.

llvm-svn: 75445

InstCombiner::visitSelectInstWithICmp.

llvm-svn: 75409

Make llvm_unreachable take an optional string, thus moving the cerr<< out of
line.
LLVM_UNREACHABLE is now a simple wrapper that makes the message go away for
NDEBUG builds.

llvm-svn: 75379

and abort()/exit() -> llvm_report_error().

llvm-svn: 75363

per icmp predicate out of predsimplify and into ConstantRange.

Add another utility method that determines whether one range is a subset of
another. Combine with the former to determine whether icmp pred range, range
is known to be true or not.

llvm-svn: 75357

llvm-svn: 75255

This started as a small change, I swear.  Unfortunately, lots of things call the [I|F]CmpInst constructors.  Who knew!?

llvm-svn: 75200

llvm-svn: 75159

llvm-svn: 75040

This way ScalarEvolution can examine the loop to determine what state
it needs to update, if it chooses.

llvm-svn: 75029

llvm-svn: 75025

these instructions, no autoupgrade or backwards compatibility support is
provided.

llvm-svn: 74991

llvm-svn: 74985

llvm-svn: 74918

llvm-svn: 74878

Finish LLVMContext-ing lib/Analysis.  This required pushing LLVMContext's through the ValueTracking API.

llvm-svn: 74873

llvm-svn: 74844

llvm-svn: 74807

llvm-svn: 74781

llvm-svn: 74753

llvm-svn: 74748

This was considering vector intrinsics to have cost 2, but non-vector
intrinsics to have cost 1, which is backward.

llvm-svn: 74698

a key is present in a std::map or DenseMap to use find instead.

llvm-svn: 74676

PassManager was scheduling LCSSA before LoopSimplify, which does not
preserve LCSSA.

llvm-svn: 74661

llvm-svn: 74646

doesn't have an IV-based operand. This fixes PR4471.

llvm-svn: 74399

llvm-svn: 74395

inserted to replace that value must dominate all of of the basic
blocks associated with the uses of the value in the PHI, not just
one of them.

llvm-svn: 74376

This helps it avoid reusing an instruction that doesn't dominate all
of the users, in cases where the original instruction was inserted
before all of the users were known.  This may result in redundant
expansions of sub-expressions that depend on loop-unpredictable values
in some cases, however this isn't very common, and it primarily impacts
IndVarSimplify, so GVN can be expected to clean these up.

This eliminates the need for IndVarSimplify's FixUsesBeforeDefs,
which fixes several bugs.

llvm-svn: 74352

llvm-svn: 74330

llvm-svn: 74285