llvm-svn: 57586

llvm-svn: 57582

llvm-svn: 57579

llvm-svn: 57557

llvm-svn: 57096

llvm-svn: 54985

llvm-svn: 54603

llvm-svn: 54602

llvm-svn: 53535

llvm-svn: 51819

llvm-svn: 51818

llvm-svn: 51222

llvm-svn: 48965

llvm-svn: 48583

llvm-svn: 48438

llvm-svn: 47831

llvm-svn: 47803

llvm-svn: 47720

llvm-svn: 47705

llvm-svn: 47280

llvm-svn: 47279

llvm-svn: 45914

llvm-svn: 45854

llvm-svn: 45837

llvm-svn: 45766

llvm-svn: 45720

llvm-svn: 45698

llvm-svn: 45408

llvm-svn: 45393

llvm-svn: 45388

llvm-svn: 45377

Fold certain additions through selects (and their compares) so as to eliminate subtractions. This code is often produced by the SMAX expansion in SCEV.

This implements test/Transforms/InstCombine/2007-12-18-AddSelCmpSub.ll

llvm-svn: 45158

llvm-svn: 45141

_foo:
	movl	$12, %eax
	andl	4(%esp), %eax
	movl	_array(%eax), %eax
	ret

instead of:

_foo:
	movl	4(%esp), %eax
	shrl	$2, %eax
	andl	$3, %eax
	movl	_array(,%eax,4), %eax
	ret

As it turns out, this triggers all the time, in a wide variety of
situations, for example, I see diffs like this in various programs:

-       movl    8(%eax), %eax
-       shll    $2, %eax
-       andl    $1020, %eax
-       movl    (%esi,%eax), %eax
+       movzbl  8(%eax), %eax
+       movl    (%esi,%eax,4), %eax


-       shll    $2, %edx
-       andl    $1020, %edx
-       movl    (%edi,%edx), %edx
+       andl    $255, %edx
+       movl    (%edi,%edx,4), %edx

Unfortunately, I also see stuff like this, which can be fixed in the
X86 backend:

-       andl    $85, %ebx
-       addl    _bit_count(,%ebx,4), %ebp
+       shll    $2, %ebx
+       andl    $340, %ebx
+       addl    _bit_count(%ebx), %ebp

llvm-svn: 44656

llvm-svn: 44638

llvm-svn: 42573

llvm-svn: 36811

upgrade the syntax of some other examples.

llvm-svn: 36806

llvm-svn: 35296

llvm-svn: 35143