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271 Commits

Author SHA1 Message Date
Benjamin Kramer 6020ed9d99 X86: Lower a select directly to a setcc_carry if possible. 
int test(unsigned long a, unsigned long b) { return -(a < b); }
compiles to
  _test:                              ## @test
    cmpq  %rsi, %rdi                  ## encoding: [0x48,0x39,0xf7]
    sbbl  %eax, %eax                  ## encoding: [0x19,0xc0]
    ret                               ## encoding: [0xc3]
instead of
  _test:                              ## @test
    xorl  %ecx, %ecx                  ## encoding: [0x31,0xc9]
    cmpq  %rsi, %rdi                  ## encoding: [0x48,0x39,0xf7]
    movl  $-1, %eax                   ## encoding: [0xb8,0xff,0xff,0xff,0xff]
    cmovael %ecx, %eax                ## encoding: [0x0f,0x43,0xc1]
    ret                               ## encoding: [0xc3]

llvm-svn: 122451
 2010-12-22 23:09:28 +00:00
Benjamin Kramer c8b035d006 Factor the (x & 2^n) ? 2^m : 0 instcombine into its own method and generalize it 
to catch cases where n != m with a shift.

llvm-svn: 121608
 2010-12-11 09:42:59 +00:00
Evan Cheng d4b0873c06 Enable sibling call optimization of libcalls which are expanded during 
legalization time. Since at legalization time there is no mapping from
SDNode back to the corresponding LLVM instruction and the return
SDNode is target specific, this requires a target hook to check for
eligibility. Only x86 and ARM support this form of sibcall optimization
right now.
rdar://8707777

llvm-svn: 120501
 2010-11-30 23:55:39 +00:00
Chris Lattner 5d2262dc76 apparently tailcalls are better on darwin/x86-64 than on linux? 
llvm-svn: 119947
 2010-11-21 18:59:20 +00:00
Dan Gohman 3c9b5f394b Don't narrow the load and store in a load+twiddle+store sequence unless 
there are clearly no stores between the load and the store. This fixes
this miscompile reported as PR7833.

This breaks the test/CodeGen/X86/narrow_op-2.ll optimization, which is
safe, but awkward to prove safe. Move it to X86's README.txt.

llvm-svn: 112861
 2010-09-02 21:18:42 +00:00
Eli Friedman f75de6eae7 A couple of small missed optimizations. 
llvm-svn: 112411
 2010-08-29 05:07:40 +00:00
Eric Christopher 9a77382685 Custom lower the memory barrier instructions and add support 
for lowering without sse2.  Add a couple of new testcases.

Fixes a few libgomp tests and latent bugs.  Remove a few todos.

llvm-svn: 109078
 2010-07-22 02:48:34 +00:00
Eli Friedman 1f41303260 Remove a fixed item, update a couple partially-fixed items. 
llvm-svn: 105375
 2010-06-03 01:01:48 +00:00
Dan Gohman 312d604ee2 This is now done. 
llvm-svn: 97450
 2010-03-01 17:43:57 +00:00
Eli Friedman 4d4c6944e9 A few missed optimizations; the last one could have a significant impact on 
code with lots of bitfields.

llvm-svn: 95809
 2010-02-10 21:26:04 +00:00
Chris Lattner 3eb76c23dd this is an SSE-specific issue. 
llvm-svn: 93373
 2010-01-13 23:29:11 +00:00
Chris Lattner fb534d97b5 X86 if conversion + tail merging issues from PR6032. 
llvm-svn: 93372
 2010-01-13 23:28:40 +00:00
Dan Gohman 5d1987f9a0 Remove some README.txt entries which are now implemented. 
llvm-svn: 92511
 2010-01-04 20:55:05 +00:00
Eli Friedman dbe2aa91b9 A couple minor README updates. 
llvm-svn: 91823
 2009-12-21 08:03:16 +00:00
Bill Wendling fd2730ee8c Move and clarify note. 
llvm-svn: 85334
 2009-10-27 22:48:31 +00:00
Bill Wendling 2974f63cb5 Note corrected. 
llvm-svn: 85332
 2009-10-27 22:43:24 +00:00
Bill Wendling cd4d148040 Modify note. 
llvm-svn: 85331
 2009-10-27 22:40:45 +00:00
Bill Wendling a205402c16 Add a note. 
llvm-svn: 85329
 2009-10-27 22:34:43 +00:00
Evan Cheng 92df9c3323 Add a note. 
llvm-svn: 77584
 2009-07-30 08:56:19 +00:00
Chris Lattner b127c0684f remove a bogus note. 
llvm-svn: 74509
 2009-06-30 05:22:31 +00:00
Chris Lattner 5ed255e642 add a note 
llvm-svn: 74508
 2009-06-30 04:20:46 +00:00
Chris Lattner 0101f45785 another xform that is target-independent (should be done in instcombine). 
llvm-svn: 73472
 2009-06-16 06:15:56 +00:00
Chris Lattner aba55a69b1 I think instcombine should unconditionally do this xform. 
llvm-svn: 73471
 2009-06-16 06:11:35 +00:00
Eli Friedman 32ad5e9c08 Misc x86 README updates: remove a couple of already-fixed issues, 
add a few suggestions from looking at some assembly code.

llvm-svn: 73210
 2009-06-11 23:07:04 +00:00
Chris Lattner 9b65031add add some late optimizations that GCC does. It thinks these are a win 
even on Core2, not just AMD processors which was a surprise to me.

llvm-svn: 72396
 2009-05-25 20:28:19 +00:00
Chris Lattner be31b7b534 we should eventually add -march=atom and the new atom movbe instruction. 
llvm-svn: 72387
 2009-05-25 16:34:44 +00:00
Chris Lattner 4147f08e44 Move 3 "(add (select cc, 0, c), x) -> (select cc, x, (add, x, c))" 
related transformations out of target-specific dag combine into the
ARM backend.  These were added by Evan in r37685 with no testcases
and only seems to help ARM (e.g. test/CodeGen/ARM/select_xform.ll).

Add some simple X86-specific (for now) DAG combines that turn things
like cond ? 8 : 0  -> (zext(cond) << 3).  This happens frequently
with the recently added cp constant select optimization, but is a
very general xform.  For example, we now compile the second example
in const-select.ll to:

_test:
        movsd   LCPI2_0, %xmm0
        ucomisd 8(%esp), %xmm0
        seta    %al
        movzbl  %al, %eax
        movl    4(%esp), %ecx
        movsbl  (%ecx,%eax,4), %eax
        ret

instead of:

_test:
        movl    4(%esp), %eax
        leal    4(%eax), %ecx
        movsd   LCPI2_0, %xmm0
        ucomisd 8(%esp), %xmm0
        cmovbe  %eax, %ecx
        movsbl  (%ecx), %eax
        ret

This passes multisource and dejagnu.

llvm-svn: 66779
 2009-03-12 06:52:53 +00:00
Dan Gohman b0d4009ec8 Add more information to the EFLAGS note. 
llvm-svn: 66515
 2009-03-10 00:26:23 +00:00
Dan Gohman d5b35ee215 Add a note about EFLAGS optimization. 
llvm-svn: 66508
 2009-03-09 23:47:02 +00:00
Chris Lattner 393ac62837 add a note. 
llvm-svn: 66360
 2009-03-08 03:04:26 +00:00
Chris Lattner cfd1f7aa9f add a note. 
llvm-svn: 66359
 2009-03-08 01:54:43 +00:00
Chris Lattner cba4b6f83d add a horrible note 
llvm-svn: 64719
 2009-02-17 01:16:14 +00:00
Dan Gohman f6ccacba36 MachineLICM now handles these cases. 
llvm-svn: 64620
 2009-02-15 23:24:52 +00:00
Chris Lattner 1aca40e349 add a note. 
llvm-svn: 64093
 2009-02-08 20:44:19 +00:00
Chris Lattner 527dd60430 add a note 
llvm-svn: 60632
 2008-12-06 22:49:05 +00:00
Eli Friedman e9ef170d4a A couple small cleanups, plus a new potential optimization. 
llvm-svn: 60286
 2008-11-30 07:52:27 +00:00
Evan Cheng 2d1937ede5 Add a README entry. 
llvm-svn: 59052
 2008-11-11 17:35:52 +00:00
Torok Edwin 33986d8f17 move the note to the correct README 
llvm-svn: 58104
 2008-10-24 19:23:07 +00:00
Dan Gohman b1d8d6ecff This is done. 
llvm-svn: 57733
 2008-10-17 21:38:40 +00:00
Evan Cheng 4884f87822 This is done. 
llvm-svn: 55348
 2008-08-26 01:13:44 +00:00
Nate Begeman 3851e29e20 Remove unnecessary readme entry 
llvm-svn: 53722
 2008-07-17 17:21:14 +00:00
Dan Gohman 02a2aaf2e7 Add a note about a potential PIC optimization. 
llvm-svn: 52663
 2008-06-24 00:53:07 +00:00
Chris Lattner 6e2bf7c67e add a micro optzn. 
llvm-svn: 50681
 2008-05-05 23:19:45 +00:00
Chris Lattner a89143f1e0 Add an ugly note. 
llvm-svn: 50029
 2008-04-21 04:46:30 +00:00
Evan Cheng 81e0c9a32c New entry. 
llvm-svn: 48912
 2008-03-28 07:07:06 +00:00
Evan Cheng 58db865d6e Remove duplicated entries. 
llvm-svn: 48714
 2008-03-23 22:56:07 +00:00
Christopher Lamb 8fe9109469 Fix X86's isTruncateFree to not claim that truncate to i1 is free. This fixes Bill's testcase that failed for r48491. 
llvm-svn: 48542
 2008-03-19 08:30:06 +00:00
Chris Lattner 477d0f5294 Add an issue that is preventing instcombine from doing a simplification. 
llvm-svn: 48356
 2008-03-14 06:00:19 +00:00
Chris Lattner a76e23a935 move these to the appropriate file 
llvm-svn: 48054
 2008-03-08 22:28:45 +00:00
Gabor Greif 636ab19205 some more spelling changes 
llvm-svn: 47996
 2008-03-06 10:51:21 +00:00