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210 Commits

Author SHA1 Message Date
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