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171 Commits

Author SHA1 Message Date
Owen Anderson
0839d3930a Fix comment. 
llvm-svn: 122788
 2011-01-03 23:51:56 +00:00
Chris Lattner
02a9776b64 reduce redundancy in the hashing code and other misc cleanups. 
llvm-svn: 122720
 2011-01-03 01:10:08 +00:00
Chris Lattner
8fac5db251 add DEBUG and -stats output to earlycse. 
Teach it to CSE the rest of the non-side-effecting instructions.

llvm-svn: 122716
 2011-01-02 23:19:45 +00:00
Chris Lattner
9c69406f2b fix a miscompilation of tramp3d-v4: when forming a memcpy, we have to make 
sure that the loop we're promoting into a memcpy doesn't mutate the input
of the memcpy.  Before we were just checking that the dest of the memcpy
wasn't mod/ref'd by the loop.

llvm-svn: 122712
 2011-01-02 21:14:18 +00:00
Chris Lattner
5702a43c09 If a loop iterates exactly once (has backedge count = 0) then don't 
mess with it.  We'd rather peel/unroll it than convert all of its 
stores into memsets.

llvm-svn: 122711
 2011-01-02 20:24:21 +00:00
Chris Lattner
8455b6e45e enhance loop idiom recognition to scan *all* unconditionally executed 
blocks in a loop, instead of just the header block.  This makes it more
aggressive, able to handle Duncan's Ada examples.

llvm-svn: 122704
 2011-01-02 19:01:03 +00:00
Chris Lattner
0469e01c02 add a list of opportunities for future improvement. 
llvm-svn: 122701
 2011-01-02 18:32:09 +00:00
Chris Lattner
ddf58010bd Allow loop-idiom to run on multiple BB loops, but still only scan the loop 
header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.

llvm-svn: 122685
 2011-01-02 07:58:36 +00:00
Chris Lattner
5b5a043d82 remove debugging code. 
llvm-svn: 122683
 2011-01-02 07:37:13 +00:00
Chris Lattner
12f91befce add some -stats output. 
llvm-svn: 122682
 2011-01-02 07:36:44 +00:00
Chris Lattner
85b6d81d41 teach loop idiom recognition to form memcpy's from simple loops. 
llvm-svn: 122678
 2011-01-02 03:37:56 +00:00
Chris Lattner
a3514441e0 add a validity check that was missed, fixing a crash on the 
new testcase.

llvm-svn: 122662
 2011-01-01 20:12:04 +00:00
Chris Lattner
91a4435875 improve validity check to handle constant-trip-count loops more 
aggressively.  In practice, this doesn't help anything though,
see the todo.

llvm-svn: 122660
 2011-01-01 19:54:22 +00:00
Chris Lattner
8b3baf6d75 implement the "no aliasing accesses in loop" safety check. This pass 
should be correct now.

llvm-svn: 122659
 2011-01-01 19:39:01 +00:00
Chris Lattner
65a699d4d0 simplify this, isBytewiseValue handles the extra check. We still 
check for "multiple of a byte" in size to make it clear that the
>> 3 below is safe.

llvm-svn: 122604
 2010-12-28 18:53:48 +00:00
Duncan Sands
5cf10e691b Silence gcc warning about an unused variable when doing a release build. 
llvm-svn: 122593
 2010-12-28 09:41:15 +00:00
Chris Lattner
cb18bfa3d2 fix some issues Frits noticed, add AliasAnalysis as a dependency 
llvm-svn: 122585
 2010-12-27 18:39:08 +00:00
Chris Lattner
b9fe685b9a have loop-idiom nuke instructions that feed stores that get removed. 
llvm-svn: 122574
 2010-12-27 00:03:23 +00:00
Chris Lattner
29e14edc8d implement enough of the memset inference algorithm to recognize and insert 
memsets.  This is still missing one important validity check, but this is enough
to compile stuff like this:

void test0(std::vector<char> &X) {
  for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I)
    *I = 0;
}

void test1(std::vector<int> &X) {
  for (long i = 0, e = X.size(); i != e; ++i)
    X[i] = 0x01010101;
}

With:
 $ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc 

to:

__Z5test0RSt6vectorIcSaIcEE:            ## @_Z5test0RSt6vectorIcSaIcEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rsi
	cmpq	%rsi, %rax
	je	LBB0_2
## BB#1:                                ## %bb.nph
	subq	%rax, %rsi
	movq	%rax, %rdi
	callq	___bzero
LBB0_2:                                 ## %for.end
	addq	$8, %rsp
	ret
...
__Z5test1RSt6vectorIiSaIiEE:            ## @_Z5test1RSt6vectorIiSaIiEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rdx
	subq	%rax, %rdx
	cmpq	$4, %rdx
	jb	LBB1_2
## BB#1:                                ## %for.body.preheader
	andq	$-4, %rdx
	movl	$1, %esi
	movq	%rax, %rdi
	callq	_memset
LBB1_2:                                 ## %for.end
	addq	$8, %rsp
	ret

llvm-svn: 122573
 2010-12-26 23:42:51 +00:00
Chris Lattner
7c5f9c35d1 sketch more of this out. 
llvm-svn: 122567
 2010-12-26 20:45:45 +00:00
Chris Lattner
81ae3f299a actually add the file... 
llvm-svn: 122563
 2010-12-26 19:39:38 +00:00