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74 Commits

Author SHA1 Message Date
Lang Hames de7ab801cc Add a natural stack alignment field to TargetData, and prevent InstCombine from 
promoting allocas to preferred alignments that exceed the natural
alignment. This avoids some potentially expensive dynamic stack realignments.

The natural stack alignment is set in target data strings via the "S<size>"
option. Size is in bits and must be a multiple of 8. The natural stack alignment
defaults to "unspecified" (represented by a zero value), and the "unspecified"
value does not prevent any alignment promotions. Target maintainers that care
about avoiding promotions should explicitly add the "S<size>" option to their
target data strings.

llvm-svn: 141599
 2011-10-10 23:42:08 +00:00
Benjamin Kramer 69affe6a94 Add a note about SSE4.1 roundss/roundsd. 
llvm-svn: 125438
 2011-02-12 17:58:16 +00:00
Chris Lattner 5cac0f71ca update this. 
llvm-svn: 113116
 2010-09-05 20:22:09 +00:00
Chris Lattner aecf47a5cb we should pattern match the SSE complex arithmetic ops. 
llvm-svn: 112109
 2010-08-25 23:31:42 +00:00
Chris Lattner a42202e0e4 random improvement for variable shift codegen. 
llvm-svn: 111813
 2010-08-23 17:30:29 +00:00
Jakob Stoklund Olesen 98ee37d878 Remove obsolete README_SSE note. 
We are generating movaps for all XMM register copies, including scalar
floating point values. This is known to be at least as good as movss and movsd
for all known architectures up to and including Nehalem because it avoids a
partial register stall.

The SSEDomainFix pass will switch movaps to movdqa when appropriate (i.e., when
operands come from the integer unit). We don't now that switching movaps to
movapd has any benefit.

The same applies to andps -> pand.

llvm-svn: 108096
 2010-07-11 17:13:42 +00:00
Chris Lattner 7b909ac785 some notes about suboptimal insertps's 
llvm-svn: 107613
 2010-07-05 05:48:41 +00:00
Eli Friedman ceb13f2af3 Remove some already-fixed README entries. 
llvm-svn: 105377
 2010-06-03 01:47:31 +00:00
Eli Friedman a59b7a72b9 Remove README entry which no longer compiles to something sane. 
llvm-svn: 105376
 2010-06-03 01:16:51 +00:00
Dan Gohman 6f34abd092 Floating-point add, sub, and mul are now spelled fadd, fsub, and fmul, 
respectively.

llvm-svn: 97531
 2010-03-02 01:11:08 +00:00
Dan Gohman 4a618827de Fix "the the" and similar typos. 
llvm-svn: 95781
 2010-02-10 16:03:48 +00:00
Chris Lattner cf11e602a2 add a note from PR6194 
llvm-svn: 95649
 2010-02-09 05:45:29 +00:00
Chris Lattner fb5670fc16 move the PR6214 microoptzn to this file. 
llvm-svn: 95299
 2010-02-04 07:32:01 +00:00
Chris Lattner 3eb76c23dd this is an SSE-specific issue. 
llvm-svn: 93373
 2010-01-13 23:29:11 +00:00
Chris Lattner e84a7911c4 Bill implemented this. 
llvm-svn: 63752
 2009-02-04 19:09:07 +00:00
Chris Lattner 553fd7e1eb add a note, this is why we're faster at SciMark-MonteCarlo with 
SSE disabled.

llvm-svn: 63751
 2009-02-04 19:08:01 +00:00
Evan Cheng f31f288863 The memory alignment requirement on some of the mov{h|l}p{d|s} patterns are 16-byte. That is overly strict. These instructions read / write f64 memory locations without alignment requirement. 
llvm-svn: 63195
 2009-01-28 08:35:02 +00:00
Chris Lattner 9a8eb0d534 add a note 
llvm-svn: 56391
 2008-09-20 19:17:53 +00:00
Chris Lattner f076d5eea8 add a note 
llvm-svn: 54964
 2008-08-19 00:41:02 +00:00
Evan Cheng 3fc2372d3a - Fix a x86 vector isel bug: illegal transformation of a vector_shuffle into a 
shift.
- Add a readme entry for a missing vector_shuffle optimization that results in
  awful codegen.

llvm-svn: 52740
 2008-06-25 20:52:59 +00:00
Evan Cheng 8647b875cc This is done. 
llvm-svn: 51526
 2008-05-24 00:10:13 +00:00
Evan Cheng 04d24edcbb Use movlps / movhps to modify low / high half of 16-byet memory location. 
llvm-svn: 51501
 2008-05-23 21:23:16 +00:00
Dan Gohman 66eea1b9b3 Elaborate on the entry on integer vector multiplication by constants. 
llvm-svn: 51491
 2008-05-23 18:05:39 +00:00
Evan Cheng d25cb8e0d2 New entry. 
llvm-svn: 51487
 2008-05-23 17:28:11 +00:00
Chris Lattner 3546c2b4e4 we compile multiply-by-constant into horrible code. Doesn't sse4 have some 
instruction for doing this?

llvm-svn: 51473
 2008-05-23 04:29:53 +00:00
Chris Lattner 03ce206143 add a note 
llvm-svn: 51062
 2008-05-13 19:56:20 +00:00
Chris Lattner d17f58ae6e add a note 
llvm-svn: 51060
 2008-05-13 18:48:54 +00:00
Evan Cheng 1120279ae6 Instead of a vector load, shuffle and then extract an element. Load the element from address with an offset. 
pshufd $1, (%rdi), %xmm0
        movd %xmm0, %eax
=>
        movl 4(%rdi), %eax

llvm-svn: 51026
 2008-05-13 08:35:03 +00:00
Evan Cheng 3f40c69083 On x86, it's safe to treat i32 load anyext as a normal i32 load. Ditto for i8 anyext load to i16. 
llvm-svn: 51019
 2008-05-13 00:54:02 +00:00
Evan Cheng b980f6fb3d Xform bitconvert(build_pair(load a, load b)) to a single load if the load locations are at the right offset from each other. 
llvm-svn: 51008
 2008-05-12 23:04:07 +00:00
Anton Korobeynikov a38e72d247 Add note 
llvm-svn: 50959
 2008-05-11 14:33:15 +00:00
Chris Lattner aeb23a8a34 add a note, this is actually not too bad to implement. 
llvm-svn: 49466
 2008-04-10 05:54:50 +00:00
Chris Lattner c692188075 move the x86-32 part of PR2108 here. 
llvm-svn: 49465
 2008-04-10 05:37:47 +00:00
Chris Lattner b6387c8a74 Finish implementing a readme entry: when inserting an i64 variable 
into a vector of zeros or undef, and when the top part is obviously
zero, we can just use movd + shuffle.  This allows us to compile
vec_set-B.ll into:

_test3:
	movl	$1234567, %eax
	andl	4(%esp), %eax
	movd	%eax, %xmm0
	ret

instead of:

_test3:
	subl	$28, %esp
	movl	$1234567, %eax
	andl	32(%esp), %eax
	movl	%eax, (%esp)
	movl	$0, 4(%esp)
	movq	(%esp), %xmm0
	addl	$28, %esp
	ret

llvm-svn: 48090
 2008-03-09 05:42:06 +00:00
Chris Lattner 93930dc28c add a note 
llvm-svn: 48064
 2008-03-09 01:08:22 +00:00
Chris Lattner eef374c197 Implement a readme entry, compiling 
#include <xmmintrin.h>
__m128i doload64(short x) {return _mm_set_epi16(0,0,0,0,0,0,0,1);}

into:
	movl	$1, %eax
	movd	%eax, %xmm0
	ret

instead of a constant pool load.

llvm-svn: 48063
 2008-03-09 01:05:04 +00:00
Chris Lattner 35adf46967 This one looks easy, add a note. 
llvm-svn: 48055
 2008-03-08 22:32:39 +00:00
Chris Lattner a76e23a935 move these to the appropriate file 
llvm-svn: 48054
 2008-03-08 22:28:45 +00:00
Chris Lattner 7c08a01698 evan implemented this. 
llvm-svn: 47948
 2008-03-05 17:11:51 +00:00
Chris Lattner 2acd0c25f6 add a note 
llvm-svn: 47939
 2008-03-05 07:22:39 +00:00
Chris Lattner a70df9e2ee Evan implemented these. 
llvm-svn: 47828
 2008-03-02 18:05:14 +00:00
Chris Lattner eb63b09206 upgrade some entries, remove stuff that is done. 
llvm-svn: 47109
 2008-02-14 06:19:02 +00:00
Nate Begeman eea32990a9 readme updates 
llvm-svn: 47051
 2008-02-13 07:06:12 +00:00
Nate Begeman 2d77e8e446 Enable SSE4 codegen and pattern matching. 
Add some notes to the README.

llvm-svn: 46949
 2008-02-11 04:19:36 +00:00
Chris Lattner 2e4719ec55 add a note 
llvm-svn: 46413
 2008-01-27 07:31:41 +00:00
Chris Lattner 2dd23b9f32 Add some notes. 
llvm-svn: 46405
 2008-01-26 20:12:07 +00:00
Chris Lattner d2b8a36f0e One readme entry is done, one is really easy (Evan, want to investigate 
eliminating the llvm.x86.sse2.loadl.pd intrinsic?), one shuffle optzn
may be done (if shufps is better than pinsw, Evan, please review), and
we already know about LICM of simple instructions.

llvm-svn: 45407
 2007-12-29 19:31:47 +00:00
Evan Cheng 78c460c8c4 New entry. 
llvm-svn: 45280
 2007-12-21 01:31:58 +00:00
Chris Lattner 909a54ccd4 add a note. 
llvm-svn: 43444
 2007-10-29 06:19:48 +00:00
Bill Wendling 855011e5c6 Small label changes. 
llvm-svn: 42549
 2007-10-02 21:02:53 +00:00