llvm-svn: 119716

Completely rework the datastructure GVN uses to represent the value number to leader mapping.  Previously,
this was a tree of hashtables, and a query recursed into the table for the immediate dominator ad infinitum
if the initial lookup failed.  This led to really bad performance on tall, narrow CFGs.

We can instead replace it with what is conceptually a multimap of value numbers to leaders (actually
represented by a hashtable with a list of Value*'s as the value type), and then
determine which leader from that set to use very cheaply thanks to the DFS numberings maintained by
DominatorTree.  Because there are typically few duplicates of a given value, this scan tends to be
quite fast.  Additionally, we use a custom linked list and BumpPtr allocation to avoid any unnecessary
allocation in representing the value-side of the multimap.

This change brings with it a 15% (!) improvement in the total running time of GVN on 403.gcc, which I
think is pretty good considering that includes all the "real work" being done by MemDep as well.

The one downside to this approach is that we can no longer use GVN to perform simple conditional progation,
but that seems like an acceptable loss since we now have LVI and CorrelatedValuePropagation to pick up
the slack.  If you see conditional propagation that's not happening, please file bugs against LVI or CVP.

llvm-svn: 119714

instruction. Any that may be expanded otherwise by MC lowering should
override this value. rdar://8683274

llvm-svn: 119713

llvm-svn: 119712

llvm-svn: 119711

llvm-svn: 119708

simple form of INITIALIZE_PASS.

llvm-svn: 119707

llvm-svn: 119706

llvm-svn: 119705

enabling more PRE. PR8586.

llvm-svn: 119704

saying "it would be bad", give an example of what is going on.

llvm-svn: 119695

refusing to optimize two memcpy's like this:

copy A <- B
copy C <- A

if it couldn't prove that noalias(B,C).  We can eliminate
the copy by producing a memmove instead of memcpy.

llvm-svn: 119694

llvm-svn: 119693

source and dest are known to not overlap.

llvm-svn: 119692

there is no need to check to see if the source and dest of a memcpy are noalias,
behavior is undefined if not.

llvm-svn: 119691

llvm-svn: 119690

out of processMemCpy into its own function.

llvm-svn: 119687

if it is passed as a byval argument.  The byval argument will just be a
read, so it is safe to read from the original global instead.  This allows
us to promote away the %agg.tmp alloca in PR8582

llvm-svn: 119686

to ignore calls that obviously can't modify the alloca
because they are readonly/readnone.

llvm-svn: 119683

optimization.  If the alloca that is "memcpy'd from constant" also has
a memcpy from *it*, ignore it: it is a load.  We now optimize the testcase to:

define void @test2() {
  %B = alloca %T
  %a = bitcast %T* @G to i8*
  %b = bitcast %T* %B to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %b, i8* %a, i64 124, i32 4, i1 false)
  call void @bar(i8* %b)
  ret void
}

previously we would generate:

define void @test() {
  %B = alloca %T
  %b = bitcast %T* %B to i8*
  %G.0 = getelementptr inbounds %T* @G, i32 0, i32 0
  %tmp3 = load i8* %G.0, align 4
  %G.1 = getelementptr inbounds %T* @G, i32 0, i32 1
  %G.15 = bitcast [123 x i8]* %G.1 to i8*
  %1 = bitcast [123 x i8]* %G.1 to i984*
  %srcval = load i984* %1, align 1
  %B.0 = getelementptr inbounds %T* %B, i32 0, i32 0
  store i8 %tmp3, i8* %B.0, align 4
  %B.1 = getelementptr inbounds %T* %B, i32 0, i32 1
  %B.12 = bitcast [123 x i8]* %B.1 to i8*
  %2 = bitcast [123 x i8]* %B.1 to i984*
  store i984 %srcval, i984* %2, align 1
  call void @bar(i8* %b)
  ret void
}

llvm-svn: 119682

llvm-svn: 119681

  sahf	movl	344(%rdi),%r14d
we used to produce:

t.s:2:1: error: unexpected token in argument list

^

we now produce:
t.s:1:11: error: unexpected token in argument list
sahf	movl	344(%rdi),%r14d
    	    	^

rdar://8581401

llvm-svn: 119676

The attached patch fixes IRBuilder and the NoFolder class so that when
NoFolder is used the instructions it generates are treated just like
the ones IRBuilder creates directly (insert into block, assign them a
name and debug info, as applicable).
It does this by
1) having NoFolder return Instruction*s instead of Value*s,
2) having IRBuilder call Insert(Value, Name) on values obtained from
the folder like it does on instructions it creates directly, and
3) adding an Insert(Constant*, const Twine& = "") overload which just
returns the constant so that the other folders shouldn't have any
extra overhead as long as inlining is enabled.

While I was there, I also added some missing (CreateFNeg and various
Create*Cast) methods to NoFolder.

llvm-svn: 119614

and testing is easier.  A good example is the unknown-location.ll test that
now can just look for ".loc 1 0 0".  We also don't use a DW_LNE_set_address for
every address change anymore.

llvm-svn: 119613

llvm-svn: 119610

llvm-svn: 119608

the operand to the pattern.

llvm-svn: 119607

llvm-svn: 119606

memset; we may need it to decide between MOVAPS and MOVUPS
later.  Adjust a test that was looking for wrong code.
PR 3866 / 8675131.

llvm-svn: 119605

llvm-svn: 119604

llvm-svn: 119603

just pretend to be.

llvm-svn: 119602

llvm-svn: 119601

This is because of bug 331418 on Microsoft Connect.

llvm-svn: 119600

llvm-svn: 119599

common encoding information.

llvm-svn: 119598

llvm-svn: 119597

queries, and SCEVExpander getRelevantLoop queries.

llvm-svn: 119595

llvm-svn: 119593

llvm-svn: 119592