codegen has no apparent problem with the trunc version of this, because it turns
into a simple subreg idiom

llvm-svn: 93202

trunc has multiple uses.  Codegen is not able to coalesce the subreg case 
correctly and so this leads to higher register pressure and spilling (see PR5997).

This speeds up 256.bzip2 from 8.60 -> 8.04s on my machine, ~7%.

llvm-svn: 93200

good code on PR4216:

_test_bitfield:                                             ## @test_bitfield
	orl	$32962, %edi
	movl	$4294941946, %eax
	andq	%rdi, %rax
	ret

instead of:

_test_bitfield:
        movl    $4294941696, %ecx
        movl    %edi, %eax
        orl     $194, %edi
        orl     $32768, %eax
        andq    $250, %rdi
        andq    %rax, %rcx
        movq    %rdi, %rax
        orq     %rcx, %rax
        ret

Evan is looking into the remaining andq+imm -> andl optimization.

llvm-svn: 93147

BitsToClear case.  This allows it to promote expressions which have an
and/or/xor after the lshr, promoting cases like test2 (from PR4216) 
and test3 (random extample extracted from a spec benchmark).

clang now compiles the code in PR4216 into:

_test_bitfield:                                             ## @test_bitfield
	movl	%edi, %eax
	orl	$194, %eax
	movl	$4294902010, %ecx
	andq	%rax, %rcx
	orl	$32768, %edi
	andq	$39936, %rdi
	movq	%rdi, %rax
	orq	%rcx, %rax
	ret

instead of:

_test_bitfield:                                             ## @test_bitfield
	movl	%edi, %eax
	orl	$194, %eax
	movl	$4294902010, %ecx
	andq	%rax, %rcx
	shrl	$8, %edi
	orl	$128, %edi
	shlq	$8, %rdi
	andq	$39936, %rdi
	movq	%rdi, %rax
	orq	%rcx, %rax
	ret

which is still not great, but is progress.

llvm-svn: 93145

new BitsToClear result which allows us to start promoting
expressions that end with a lshr-by-constant.  This is
conservatively correct and better than what we had before
(see testcases) but still needs to be extended further.

llvm-svn: 93144

llvm-svn: 93143

the dest of the sext.

llvm-svn: 93128

the zext dest type.  This allows us to handle test52/53 in cast.ll,
and allows llvm-gcc to generate much better code for PR4216 in -m64
mode:

_test_bitfield:                                             ## @test_bitfield
	orl	$32962, %edi
	movl	%edi, %eax
	andl	$-25350, %eax
	ret

This also fixes a bug handling vector extends, ensuring that the
mask produced is a vector constant, not an integer constant.

llvm-svn: 93127

simpler profitability predicate.

llvm-svn: 93111

llvm-svn: 93110

elimination of a sign extend to be a win, which simplifies 
the client of CanEvaluateSExtd, and allows us to eliminate
more casts (examples taken from real code).

llvm-svn: 93109

lshr+ashr instead of trunc+sext.  We want to avoid type 
conversions whenever possible, it is easier to codegen expressions
without truncates and extensions.

llvm-svn: 93107

llvm-svn: 93106

llvm-svn: 93105

bits known clear in the result and don't care about the # casts 
eliminated.  TD is also dead but keeping it for now.

llvm-svn: 93098

1) don't try to optimize a sext or zext that is only used by a trunc, let
   the trunc get optimized first.  This avoids some pointless effort in
   some common cases since instcombine scans down a block in the first pass.
2) Change the cost model for zext elimination to consider an 'and' cheaper
   than a zext.  This allows us to do it more aggressively, and for the next
   patch to simplify the code quite a bit.

llvm-svn: 93097

more expressions to be promoted and casts eliminated.

llvm-svn: 93096

llvm-svn: 93095

llvm-svn: 93093

llvm-svn: 93092

llvm-svn: 93091

commonIntCastTransforms into the callers, eliminating a switch,
and allowing the static predicate  methods to be moved down to
live next to the corresponding function.  No functionality 
change.

llvm-svn: 93089

base is the right expression type.  This fixes PR5981.

llvm-svn: 93045

llvm-svn: 93038

llvm-svn: 93026

llvm-svn: 93024

simplify it now that it is only used for truncates.

llvm-svn: 93021

the input is already sign extended.

llvm-svn: 93019

remove some trailing whitespace while there.

llvm-svn: 93008

llvm-svn: 93007

llvm-svn: 92964

that feeds into a zext, similar to the patch I did yesterday for sext.
There is a lot of room for extension beyond this patch.

llvm-svn: 92962

llvm-svn: 92912

are prepared to look through.

llvm-svn: 92898

llvm-svn: 92892

to an element of a vector in a static ctor) which occurs with an 
unrelated patch I'm testing.  Annoyingly, EvaluateStoreInto basically 
does exactly the same stuff as InsertElement constant folding, but it
now handles vectors, and you can't insertelement into a vector.  It
would be 'really nice' if GEP into a vector were not legal.

llvm-svn: 92889

it work for any integer size return type.

llvm-svn: 92853

phi nodes when deciding which pointers point to local memory.
I actually checked long ago how useful this is, and it isn't
very: it hardly ever fires in the testsuite, but since Chris
wants it here it is!

llvm-svn: 92836

llvm-svn: 92831

memcpy, memset and other intrinsics that only access their arguments
to be readnone if the intrinsic's arguments all point to local memory.
This improves the testcase in the README to readonly, but it could in
theory be made readnone, however this would involve more sophisticated
analysis that looks through the memcpy.

llvm-svn: 92829