use can't be dominated, saving one domtree lookup.

llvm-svn: 142066

Enhance the memdep interface so that users can tell the difference between a dependency which cannot be calculated and a path reaching the entry point of the function. This patch introduces isNonFuncLocal, which replaces isUnknown in some cases.

Patch by Xiaoyi Guo.

llvm-svn: 141896

  switch (n) {
    case 27:
      do_something(x);
    ...
  }
the call do_something(x) will be replaced with do_something(27).  In
gcc-as-one-big-file this results in the removal of about 500 lines of
bitcode (about 0.02%), so has about 1/10 of the effect of propagating
branch conditions.

llvm-svn: 141360

branch "br i1 %x, label %if_true, label %if_false" then it replaces
"%x" with "true" in places only reachable via the %if_true arm, and
with "false" in places only reachable via the %if_false arm.  Except
that actually it doesn't: if value numbering shows that %y is equal
to %x then, yes, %y will be turned into true/false in this way, but
any occurrences of %x itself are not transformed.  Fix this.  What's
more, it's often the case that %x is an equality comparison such as
"%x = icmp eq %A, 0", in which case every occurrence of %A that is
only reachable via the %if_true arm can be replaced with 0.  Implement
this and a few other variations on this theme.  This reduces the number
of lines of LLVM IR in "GCC as one big file" by 0.2%.  It has a bigger
impact on Ada code, typically reducing the number of lines of bitcode
by around 0.4% by removing repeated compiler generated checks.  Passes
the LLVM nightly testsuite and the Ada ACATS testsuite.

llvm-svn: 141177

it's OK for the false/true destination to have multiple
predecessors as long as the extra ones are dominated by
the branch destination.

llvm-svn: 141176

Stop emitting instructions with the name "tmp" they eat up memory and have to be uniqued, without any benefit.

If someone prefers %tmp42 to %42, run instnamer.

llvm-svn: 140634

will be valid. This fixes PR10820.

llvm-svn: 139005

llvm-svn: 137888

PRE needs the landing pads to have their critical edges split. Doing this for a
landing pad is non-trivial. Abandon the attempt to perform PRE when we come
across a landing pad. (Reviewed by Owen!)

llvm-svn: 137876

ConstantExpr::getInBoundsGetElementPtr to use ArrayRef.

llvm-svn: 135673

llvm-svn: 135375

Added recognition for signed add/sub/mul with overflow intrinsics to GVN as per Chris and Frits suggestion.

llvm-svn: 134777

Make GVN look through extractvalues for recognised intrinsics. GVN can then CSE ops that match values produced by the intrinsics.

llvm-svn: 134677

Change various bits of code to make better use of the existing PHINode
API, to insulate them from forthcoming changes in how PHINodes store
their operands.

llvm-svn: 133434

Add "unknown" results for memdep, which mean "I don't know whether a dependence for the given instruction exists in the given block".  This cleans up all the existing hacks in memdep which represent this concept by returning clobber with various unrelated instructions.

llvm-svn: 133031

causing it to get into infinite loops when it would widen a 
load (which can necessarily leave around dead loads).

llvm-svn: 131847

llvm-svn: 131482

llvm-svn: 131481

llvm-svn: 130895

llvm-svn: 130426

a nice and tidy:
  %x1 = load i32* %0, align 4
  %1 = icmp eq i32 %x1, 1179403647
  br i1 %1, label %if.then, label %if.end

instead of doing lots of loads and branches.  May the FreeBSD bootloader
long fit in its allocated space.

llvm-svn: 130416

llvm-svn: 130414

static functions instead of passing around tons of random ivars.

llvm-svn: 130403

llvm-svn: 130401

wider load would allow elimination of subsequent loads, and when the wider
load is still a native integer type.  This eliminates a ton of loads on 
various benchmarks involving struct fields, though it is somewhat hobbled
by clang not being very aggressive about field alignment.

This is yet another step along the way towards resolving PR6627.

llvm-svn: 130390

translation fails.  We were bailing out in some cases that would
cause us to miss GVN'ing some non-local cases away.

llvm-svn: 130206

return it as a clobber.  This allows GVN to do smart things.

Enhance GVN to be smart about the case when a small load is clobbered
by a larger overlapping load.  In this case, forward the value.  This
allows us to compile stuff like this:

int test(void *P) {
  int tmp = *(unsigned int*)P;
  return tmp+*((unsigned char*)P+1);
}

into:

_test:                                  ## @test
	movl	(%rdi), %ecx
	movzbl	%ch, %eax
	addl	%ecx, %eax
	ret

which has one load.  We already handled the case where the smaller
load was from a must-aliased base pointer.

llvm-svn: 130180

PHINode::Create() giving the (known or expected) number of operands.

llvm-svn: 128537

llvm-svn: 128535

with BasicAA's DecomposeGEPExpression, which recently began
using a TargetData. This fixes PR8968, though the testcase
is awkward to reduce.

Also, update several off GetUnderlyingObject's users
which happen to have a TargetData handy to pass it in.

llvm-svn: 124134

llvm-svn: 123288

once at the beginning of GVN instead of once per iteration.

llvm-svn: 123278

llvm-svn: 123270

actually reached in the testcase in PR8954, but it's safe and good
practice.

llvm-svn: 123224

phi nodes.  It is called from MergeBlockIntoPredecessor which is 
called from GVN, which claims to preserve these.

I'm skeptical that this is the actual problem behind PR8954, but
this is a stab in the right direction.

llvm-svn: 123222

Don't bother value numbering instructions with void types in GVN. In theory this should allow us to insert
fewer things into the value numbering maps, but any speedup is beneath the noise threshold on my machine
on 403.gcc.

llvm-svn: 122844

llvm-svn: 122828

llvm-svn: 122827

llvm-svn: 122826

Clarify terminology, settling on referring to what was the "number table" as the "leader table", and
rename methods to make it much more clear what they're doing.

llvm-svn: 122823