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Commit Graph

21 Commits

Author SHA1 Message Date
Owen Anderson
c724c5969d Fix comment.
llvm-svn: 122788
2011-01-03 23:51:56 +00:00
Chris Lattner
f6a71c6cd5 reduce redundancy in the hashing code and other misc cleanups.
llvm-svn: 122720
2011-01-03 01:10:08 +00:00
Chris Lattner
39d1fb3320 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
0c2cfcf430 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
c655681b32 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
c78e4bc366 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
bbae3ddf12 add a list of opportunities for future improvement.
llvm-svn: 122701
2011-01-02 18:32:09 +00:00
Chris Lattner
f669d6a901 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
8a72a8f315 remove debugging code.
llvm-svn: 122683
2011-01-02 07:37:13 +00:00
Chris Lattner
bbd22e0c3c add some -stats output.
llvm-svn: 122682
2011-01-02 07:36:44 +00:00
Chris Lattner
34a61ab676 teach loop idiom recognition to form memcpy's from simple loops.
llvm-svn: 122678
2011-01-02 03:37:56 +00:00
Chris Lattner
b9c1684fce 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
9a9f43c4a2 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
4651f8b037 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
51a906ce92 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
1395f115d8 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
2658d522b1 fix some issues Frits noticed, add AliasAnalysis as a dependency
llvm-svn: 122585
2010-12-27 18:39:08 +00:00
Chris Lattner
a4249272b5 have loop-idiom nuke instructions that feed stores that get removed.
llvm-svn: 122574
2010-12-27 00:03:23 +00:00
Chris Lattner
d4daf9f002 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
27961b5180 sketch more of this out.
llvm-svn: 122567
2010-12-26 20:45:45 +00:00
Chris Lattner
73f562af94 actually add the file...
llvm-svn: 122563
2010-12-26 19:39:38 +00:00