phi's in the successors

llvm-svn: 26108

with branches on partially invariant computations.

llvm-svn: 26104

llvm-svn: 26103

llvm-svn: 26102

branches in their entry block that control whether or not the loop is a noop or not.

llvm-svn: 26101

llvm-svn: 26098

llvm-svn: 26093

uses of loop values outside the loop.  We need loop-closed SSA form to do
this right, or to use SSA rewriting if we really care.

llvm-svn: 26089

llvm-svn: 26088

1. Teach it new tricks: in particular how to propagate through signed shr and sexts.
2. Teach it to return a bitset of known-1 and known-0 bits, instead of just zero.
3. Teach instcombine (AND X, C) to fold when we know all C bits of X.

This implements Regression/Transforms/InstCombine/bittest.ll, and allows
future things to be simplified.

llvm-svn: 26087

optimization where we reduce the number of bits in AND masks when possible.

llvm-svn: 26056

instruction onto the worklist (in case they are now dead).

Add a really trivial local DSE implementation to help out bitfield code.
We now fold this:

struct S {
    unsigned char a : 1, b : 1, c : 1, d : 2, e : 3;
    S();
};

S::S() : a(0), b(0), c(1), d(0), e(6) {}

to this:

void %_ZN1SC1Ev(%struct.S* %this) {
entry:
        %tmp.1 = getelementptr %struct.S* %this, int 0, uint 0
        store ubyte 38, ubyte* %tmp.1
        ret void
}

much earlier (in gccas instead of only in gccld after DSE runs).

llvm-svn: 26050

test/Regression/Transforms/SCCP/select.ll

llvm-svn: 26049

llvm-svn: 26045

llvm-svn: 26040

is just as efficient as MVIZ and is also more general.

Fix a few minor bugs introduced in recent patches

llvm-svn: 26036

mask.  This allows the code to be simpler and more efficient.

Also, generalize some of the cases in MVIZ a bit, making it slightly more aggressive.

llvm-svn: 26035

llvm-svn: 26034

'demanded bits', inspired by Nate's work in the dag combiner.  This isn't
complete, but needs to unrelated instcombiner changes to continue.

llvm-svn: 26033

Turn A / (C1 << N), where C1 is "1<<C2" into A >> (N+C2) [udiv only].

Tested with: rem.ll:test5, div.ll:test10

llvm-svn: 26003

#LLVM LOC, and auto-cse's cast instructions.

llvm-svn: 25974

1. When rewriting code in outer loops, sometimes we would insert code into
   inner loops that is invariant in that loop.
2. Notice that 4*(2+x) is 8+4*x and use that to simplify expressions.

This is a performance neutral change.

llvm-svn: 25964

llvm-svn: 25661

llvm-svn: 25587

llvm-svn: 25514

need the float->double part.

llvm-svn: 25452

llvm-svn: 25406

llvm-svn: 25363

llvm-svn: 25349

llvm-svn: 25315

llvm-svn: 25299

llvm-svn: 25294

llvm-svn: 25292

Patch written by Daniel Berlin!

llvm-svn: 25202

Patch written by Daniel Berlin!

llvm-svn: 25201

llvm-svn: 25180

llvm-svn: 25137

llvm-svn: 25130

the shifts.

This allows us to fold this (which is the 'integer add a constant' sequence
from cozmic's scheme compmiler):

int %x(uint %anf-temporary776) {
        %anf-temporary777 = shr uint %anf-temporary776, ubyte 1
        %anf-temporary800 = cast uint %anf-temporary777 to int
        %anf-temporary804 = shl int %anf-temporary800, ubyte 1
        %anf-temporary805 = add int %anf-temporary804, -2
        %anf-temporary806 = or int %anf-temporary805, 1
        ret int %anf-temporary806
}

into this:

int %x(uint %anf-temporary776) {
        %anf-temporary776 = cast uint %anf-temporary776 to int
        %anf-temporary776.mask1 = add int %anf-temporary776, -2
        %anf-temporary805 = or int %anf-temporary776.mask1, 1
        ret int %anf-temporary805
}

note that instcombine already knew how to eliminate the AND that the two
shifts fold into.  This is tested by InstCombine/shift.ll:test26

-Chris

llvm-svn: 25128

llvm-svn: 25126