llvm-svn: 53616

Have GVN do a pre-pass over the CFG that folds away unconditional branches where possible.  This allows local PRE to be more aggressive.

llvm-svn: 53615

again canonicalizes {i32} into i32 and {} into void.

llvm-svn: 53610

return value as a whole in deadargelim is really not needed now that we simply
rebuild the old return value and actually prevents some canonicalization from
taking place.

This revert stops deadargelim from changing {i32} into i32 for now, but I'll
fix that next.

llvm-svn: 53609

return values that are still (partially) live. Instead of updating all uses of
a call instruction after removing some elements, it now just rebuilds the
original struct (With undef gaps where the unused values were) and leaves it to
instcombine to clean this up.

The added testcase still fails currently, but this is due to instcombine which
isn't good enough yet. I will fix that part next.

llvm-svn: 53608

llvm-svn: 53607

only the liveness of partial return values (for functions returning a struct).
This is more explicit to prevent unwanted changes in the return value. 

In particular, deadargelim now canonicalizes a function returning {i32} to
returning i32 and {} to void, if the struct returned is not used in its
entirety, but only the single element is used.

llvm-svn: 53606

and return values live for those functions. This doesn't change anything yet,
but prepares for the coming commits.

llvm-svn: 53601

llvm-svn: 53600

RetOrArg::getDescription() as const.

llvm-svn: 53599

llvm-svn: 53598

llvm-svn: 53592

method, to slightly simplify control flow.

llvm-svn: 53591

llvm-svn: 53564

llvm-svn: 53557

llvm-svn: 53549

a hack around the fact that we don't represent the CFG correctly for sj/lj.
It fixes PR2486.

llvm-svn: 53540

llvm-svn: 53538

disproving a condition.  This actually compiles the existing testcase
(udiv_select_to_select_shift) to:

define i64 @test(i64 %X, i1 %Cond) {
entry:
	%divisor1.t = lshr i64 %X, 3		; <i64> [#uses=1]
	%quotient2 = lshr i64 %X, 3		; <i64> [#uses=1]
	%sum = add i64 %divisor1.t, %quotient2		; <i64> [#uses=1]
	ret i64 %sum
}

instead of:

define i64 @test(i64 %X, i1 %Cond) {
entry:
	%quotient1.v = select i1 %Cond, i64 3, i64 4		; <i64> [#uses=1]
	%quotient1 = lshr i64 %X, %quotient1.v		; <i64> [#uses=1]
	%quotient2 = lshr i64 %X, 3		; <i64> [#uses=1]
	%sum = add i64 %quotient1, %quotient2		; <i64> [#uses=1]
	ret i64 %sum
}

llvm-svn: 53534

fixes PR2540.

llvm-svn: 53533

No functionality change.

llvm-svn: 53532

llvm-svn: 53531

No functionality change.

llvm-svn: 53530

llvm-svn: 53528

llvm-svn: 53527

conditionals and commenting the code better.

No functionality change.

llvm-svn: 53526

Remove dead code analyzing urem. 'urem' of power-of-2 is canonicalized to an
'and' instruction.

llvm-svn: 53506

llvm-svn: 53474

llvm-svn: 53470

llvm-svn: 53454

llvm-svn: 53452

similar.

llvm-svn: 53451

llvm-svn: 53449

llvm-svn: 53448

llvm-svn: 53447

the min/max values for an integer type, compare against the min/max
values we can prove contain the input.  This might be a tighter bound,
so this is general goodness.

llvm-svn: 53446

handle them in some code.

llvm-svn: 53445

was using the algorithm for folding unsigned comparisons which is
completely wrong.  This has been broken since the signless types change.

llvm-svn: 53444

This cause a regression in InstCombine/JavaCompare, which was doing the right
thing on accident.  To handle the missed case, generalize the comparisons based
on masked bits a little bit to handle comparisons against the max value. For 
example, we can now xform (slt i32 (and X, 4), 4) -> (setne i32 (and X, 4), 4)

llvm-svn: 53443

Rewrite the DeadArgumentElimination pass, to use a more explicit tracking of
dependencies between return values and/or arguments. Also make the handling of
arguments and return values the same.

The pass now looks properly inside returned structs, but only at the first
level (ie, not inside nested structs).

This version fixed a few more bugs and was cleaned up a bit. It now passes all
of LLVM's testing, and should still pass SPEC2006. There is still a minor bug
with regard to returning nested structs. Since there is currently nothing that
emits such IR, I will fix that in a seperate commit (partly because it requires
a non-trivial fix).

llvm-svn: 53400