Commit Graph

6 Commits

Author SHA1 Message Date
Chandler Carruth fd63436553 Relax the FileCheck assertion a bit -- all we really care about is that
we're loading from the global array, not how it is spelled in the asm.
This should fix the MSVC bots.

llvm-svn: 148214
2012-01-15 09:38:59 +00:00
Chandler Carruth 4bb2eb15d4 FileCheck-ize a test, make it more specific to directly test the shift
removal desired.

llvm-svn: 148213
2012-01-15 09:32:57 +00:00
Dan Gohman 40503396da Eliminate more uses of llvm-as and llvm-dis.
llvm-svn: 81290
2009-09-08 23:54:48 +00:00
Chris Lattner eedaf92fcf third time around: instead of disabling this completely,
only disable it if we don't know it will be obviously profitable.
Still fixme, but less so. :)

llvm-svn: 44658
2007-12-06 07:47:55 +00:00
Chris Lattner b5fdfb9612 Actually, disable this code for now. More analysis and improvements to
the X86 backend are needed before this should be enabled by default.

llvm-svn: 44657
2007-12-06 07:44:31 +00:00
Chris Lattner 7c709a5d08 implement a readme entry, compiling the code into:
_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
2007-12-06 07:33:36 +00:00