leads into a cycle involving a different PHI, LSR got stuck running
around that cycle looking for the original PHI. To avoid this, keep
track of visited PHIs and stop searching if we see one more than once.
This fixes PR2570.

llvm-svn: 53879

llvm-svn: 53771

Make PRE actually handle critical edges (by splitting them).  Confirmed that bootstrap passes with this change.

llvm-svn: 53762

llvm-svn: 53761

llvm-svn: 53760

llvm-svn: 53757

llvm-svn: 53735

more than once.

llvm-svn: 53731

llvm-svn: 53730

llvm-svn: 53716

llvm-svn: 53715

llvm-svn: 53712

llvm-svn: 53705

could cause problems for memdep when it breaks critical edges.

llvm-svn: 53691

FindInsertedValue, it now performs a number of simple transformations that
should result in the same effect when applied iteratively.

llvm-svn: 53673

llvm-svn: 53666

llvm-svn: 53627

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