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281 Commits

Author SHA1 Message Date
Chandler Carruth
96b1b6c135 Add a note about a missed FP optimization. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123126 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 21:00:19 +00:00
Chandler Carruth
694d753b09 Another missed memset in std::vector initialization. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123116 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 11:29:57 +00:00
Chandler Carruth
27a2a13b62 Fix a cut-paste-o so that the sample code is correct for my last note. 
Also, switch to a more clear 'sink' function with its declaration to
avoid any confusion about 'g'. Thanks for the suggestion Frits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123113 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 10:10:59 +00:00
Chandler Carruth
e5ca494ae6 Another missed optimization of trivial vector code. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123112 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 09:58:36 +00:00
Chandler Carruth
d8723a9b55 Add a note about vector's size-constructor producing dead stores. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123111 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 09:58:33 +00:00
Chandler Carruth
75fbd3793f Add a note about a missed memset optimization from std::fill. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123103 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-09 01:32:55 +00:00
Benjamin Kramer
eaff66a895 Revert 122959, it needs more thought. Add it back to README.txt with additional notes. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123030 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-07 20:42:20 +00:00
Chris Lattner
01cdc2016d With Benjamin's recent amazing patches, we should be able to do even better things :) 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122978 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 22:25:00 +00:00
Benjamin Kramer
fa36680076 Add a note from llvmdev, this time with more info. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122966 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 17:35:50 +00:00
Benjamin Kramer
7d9f51f4b5 EarlyCSE does this now (and GVN always did it). 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122960 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 13:19:46 +00:00
Benjamin Kramer
240d42d185 InstCombine: If we call llvm.objectsize on a malloc call we can replace it with the size passed to malloc. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122959 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 13:11:05 +00:00
Chris Lattner
cce240d26b add a note about object size from drystone, add a poorly optimized loop from 179.art. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122954 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 07:41:22 +00:00
Chris Lattner
c1853e4a03 add a trivial instcombine missed in Dhrystone 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122953 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-06 07:09:23 +00:00
Chris Lattner
527b47d189 update a bunch of entries. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122700 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-02 18:31:38 +00:00
Chris Lattner
cf078f2b20 Allow loop-idiom to run on multiple BB loops, but still only scan the loop 
header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122685 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-02 07:58:36 +00:00
Chris Lattner
15df04472a a missed __builtin_object_size case. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122676 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-01 22:57:31 +00:00
Chris Lattner
9c8fb9e820 various updates. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122675 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-01 22:52:11 +00:00
Duncan Sands
124708d9b4 Revert commit 122654 at the request of Chris, who reckons that instsimplify 
is the wrong hammer for this nail, and is probably right.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122661 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-01 20:08:02 +00:00
Duncan Sands
7cf85e74e3 Fix a README item by having InstructionSimplify do a mild form of value 
numbering, in which it considers (for example) "%a = add i32 %x, %y" and
"%b = add i32 %x, %y" to be equal because the operands are equal and the
result of the instructions only depends on the values of the operands.
This has almost no effect (it removes 4 instructions from gcc-as-one-file),
and perhaps slows down compilation: I measured a 0.4% slowdown on the large
gcc-as-one-file testcase, but it wasn't statistically significant.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122654 91177308-0d34-0410-b5e6-96231b3b80d8
 2011-01-01 16:12:09 +00:00
Chris Lattner
1dc5db2beb add a note from llvmdev 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122603 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-28 18:45:02 +00:00
Benjamin Kramer
9d071cbb92 Remove/fix invalid README entries. The well thought out strcpy function doesn't return a pointer to the end of the string. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122496 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-23 15:32:07 +00:00
Chris Lattner
e5cbdca3bd recognize an unsigned add with overflow idiom into uadd. 
This resolves a README entry and technically resolves PR4916,
but we still get poor code for the testcase in that PR because
GVN isn't CSE'ing uadd with add, filed as PR8817.

Previously we got:

_test7:                                 ## @test7
	addq	%rsi, %rdi
	cmpq	%rdi, %rsi
	movl	$42, %eax
	cmovaq	%rsi, %rax
	ret

Now we get:

_test7:                                 ## @test7
	addq	%rsi, %rdi
	movl	$42, %eax
	cmovbq	%rsi, %rax
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122182 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-19 19:37:52 +00:00
Chris Lattner
9448184b99 add another overflow idiom 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121854 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-15 07:28:58 +00:00
Chris Lattner
08859ffa63 add a note about overflow idiom recognition. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121853 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-15 07:25:55 +00:00
Chris Lattner
ef17f08dbc add a shift/imul missed optimization 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121850 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-15 07:10:43 +00:00
Chris Lattner
2fc36e19b1 add a note about a SPEC hack that gcc mainline does. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121849 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-15 06:38:24 +00:00
Chris Lattner
a97c91f014 add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121656 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-13 00:15:25 +00:00
Benjamin Kramer
2f7228b80c Generalize the and-icmp-select instcombine further by allowing selects of the form 
(x & 2^n) ? 2^m+C : C

we can offset both arms by C to get the "(x & 2^n) ? 2^m : 0" form, optimize the
select to a shift and apply the offset afterwards.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121609 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-12-11 10:49:22 +00:00
Benjamin Kramer
c21a821e9f The srem -> urem transform is not safe for any divisor that's not a power of two. 
E.g. -5 % 5 is 0 with srem and 1 with urem.

Also addresses Frits van Bommel's comments.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120049 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-23 20:33:57 +00:00
Benjamin Kramer
b70ebd2aa3 InstCombine: Reduce "X shift (A srem B)" to "X shift (A urem B)" iff B is positive. 
This allows to transform the rem in "1 << ((int)x % 8);" to an and.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120028 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-23 18:52:42 +00:00
Benjamin Kramer
93f8455d73 InstCombine: Implement X - A*-B -> X + A*B. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119984 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-22 20:31:27 +00:00
Benjamin Kramer
ce750f0332 Implement the "if (X == 6 || X == 4)" -> "if ((X|2) == 6)" optimization. 
This currently only catches the most basic case, a two-case switch, but can be
extended later.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119964 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-22 09:45:38 +00:00
Chris Lattner
3e41106de4 add some random notes. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119925 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-21 07:05:31 +00:00
Chris Lattner
75d8f599e7 optimize: 
void a(int x) { if (((1<<x)&8)==0) b(); }

into "x != 3", which occurs over 100 times in 403.gcc but in no
other program in llvm-test.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119922 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-21 06:44:42 +00:00
Chris Lattner
79a980ad85 tail calls on x86 are implemented. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119920 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-21 06:10:27 +00:00
Chris Lattner
af510f16ec add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118806 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-11 18:23:57 +00:00
Chris Lattner
1e68fdb946 add pr# 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118797 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-11 17:17:56 +00:00
Chris Lattner
274191fa70 add a case we fail to devirt. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118608 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-09 19:37:28 +00:00
Duncan Sands
1ac7c9979a Fix a README item: when doing a comparison with the result 
of a select instruction, see if doing the compare with the
true and false values of the select gives the same result.
If so, that can be used as the value of the comparison.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118378 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-07 16:12:23 +00:00
Benjamin Kramer
019e378754 Add a note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118337 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-11-06 10:37:16 +00:00
Benjamin Kramer
9510a2538b Add constant folding for strspn and strcspn to SimplifyLibCalls. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115116 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-09-30 00:58:35 +00:00
Chris Lattner
313a94c3d0 idiom recognition should catch this. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114304 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-09-19 00:37:34 +00:00
Nick Lewycky
b1e4eebec0 Add optimization to Target/README.txt. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110543 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-08-08 07:04:25 +00:00
Benjamin Kramer
1db071f0da Teach instcombine to transform 
(X >s -1) ? C1 : C2 and (X <s  0) ? C2 : C1
into ((X >>s 31) & (C2 - C1)) + C1, avoiding the conditional.

This optimization could be extended to take non-const C1 and C2 but we better
stay conservative to avoid code size bloat for now.

for
int sel(int n) {
     return n >= 0 ? 60 : 100;
}

we now generate
  sarl  $31, %edi
  andl  $40, %edi
  leal  60(%rdi), %eax

instead of
  testl %edi, %edi
  movl  $60, %ecx
  movl  $100, %eax
  cmovnsl %ecx, %eax


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107866 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-07-08 11:39:10 +00:00
Eli Friedman
b482829abb Minor amendment to switch-lowering improvement. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107569 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-07-03 08:43:32 +00:00
Eli Friedman
b4a74c1d82 Note switch-lowering inefficiency. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107565 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-07-03 07:38:12 +00:00
Eric Christopher
33634d0672 Add another bswap idiom that isn't matched. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107213 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-06-29 22:22:22 +00:00
Benjamin Kramer
0f471e018f TODO-- 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106102 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-06-16 15:47:00 +00:00
Eli Friedman
8c47d3b73f Add README entry; based on testcase from Bill Hart. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105878 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-06-12 05:54:27 +00:00
Chris Lattner
c2685a9c98 add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104404 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-05-21 23:16:21 +00:00
Dan Gohman
3a2a4846a6 Add a README entry. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102906 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-05-03 14:31:00 +00:00
Chris Lattner
9484689f14 add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101581 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-04-16 23:52:30 +00:00
Chris Lattner
2392ae7d73 Implement rdar://7860110 (also in target/readme.txt) narrowing 
a load/or/and/store sequence into a narrower store when it is
safe.  Daniel tells me that clang will start producing this sort
of thing with bitfields, and this does  trigger a few dozen times
on 176.gcc produced by llvm-gcc even now.

This compiles code like CodeGen/X86/2009-05-28-DAGCombineCrash.ll 
into:

        movl    %eax, 36(%rdi)

instead of:

        movl    $4294967295, %eax       ## imm = 0xFFFFFFFF
        andq    32(%rdi), %rax
        shlq    $32, %rcx
        addq    %rax, %rcx
        movq    %rcx, 32(%rdi)

and each of the testcases into a single store.  Each of them used
to compile into craziness like this:

_test4:
	movl	$65535, %eax            ## imm = 0xFFFF
	andl	(%rdi), %eax
	shll	$16, %esi
	addl	%eax, %esi
	movl	%esi, (%rdi)
	ret




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101343 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-04-15 04:48:01 +00:00
Chris Lattner
6663670359 move PR6576 here. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98194 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-03-10 21:42:42 +00:00
Chris Lattner
cf031f6d66 move PR6212 to this file. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95624 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-02-09 00:11:10 +00:00
Eli Friedman
1144d7e3cc Remove a completed item, add a couple new ones. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94945 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-31 04:55:32 +00:00
Bob Wilson
3eb4f7e2dd Improve isSafeToLoadUnconditionally to recognize that GEPs with constant 
indices are safe if the result is known to be within the bounds of the
underlying object.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94829 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-29 19:19:08 +00:00
Chris Lattner
43dc2e6d76 reassociate should do this. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94374 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-24 20:17:09 +00:00
Chris Lattner
10c4245103 add a note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94373 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-24 20:01:41 +00:00
Chris Lattner
818ff34bc0 implement a simple instcombine xform that has been in the 
readme forever.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94318 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-23 18:49:30 +00:00
Chris Lattner
aa306c2cc1 add some notes, making posix-memalign be nocapture would be an easy improvement. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94312 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-23 17:59:23 +00:00
Eli Friedman
9cfb3adf44 Add some potentially interesting transformations to README. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93797 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-18 22:36:59 +00:00
Duncan Sands
e10920d678 Fix a README item: have functionattrs look through selects and 
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!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92836 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-06 15:37:47 +00:00
Duncan Sands
7c422ac216 Partially address a README by having functionattrs consider calls to 
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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92829 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-06 08:45:52 +00:00
Chris Lattner
e4412c1f0b implement an instcombine xform needed by clang's codegen 
on the example in PR4216.  This doesn't trigger in the testsuite,
so I'd really appreciate someone scrutinizing the logic for
correctness.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92458 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-04 06:03:59 +00:00
Chris Lattner
f031e8ad01 Teach codegen to lower llvm.powi to an efficient (but not optimal) 
multiply sequence when the power is a constant integer.  Before, our
codegen for std::pow(.., int) always turned into a libcall, which was
really inefficient.

This should also make many gfortran programs happier I'd imagine.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92388 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-01 03:32:16 +00:00
Chris Lattner
398ffba75f update this. To take the next step, llvm.powi should be generalized to work 
on integers as well and codegen should lower them to branch trees.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92382 91177308-0d34-0410-b5e6-96231b3b80d8
 2010-01-01 01:29:26 +00:00
Eli Friedman
bcae205a4b More info on this transformation. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91230 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-12-12 23:23:43 +00:00
Eli Friedman
1555473387 Remove some stuff that's already implemented. Also, remove the note about 
merging x >u 5 and x <s 20 because it's impossible to implement.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91228 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-12-12 21:41:48 +00:00
Chris Lattner
89742c2c3f expand note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90429 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-12-03 07:43:46 +00:00
Chris Lattner
053321731c add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90428 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-12-03 07:41:54 +00:00
Chris Lattner
d4137f40da update and consolidate the load pre notes. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90050 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-29 02:19:52 +00:00
Chris Lattner
1d159838a3 add a deadargelim note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90009 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-27 17:12:30 +00:00
Chris Lattner
6d94926a52 This testcase is actually only partially redundant, and requires 
the FIXME I added yesterday to be implemented.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90008 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-27 16:53:57 +00:00
Chris Lattner
20ce7c0ded this (and probably several others) are now done. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89982 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-27 00:35:04 +00:00
Chris Lattner
cc3d0eb483 Teach memdep to phi translate bitcasts. This allows us to compile 
the example in GCC PR16799 to:

LBB1_2:                                                     ## %bb1
	movl	%eax, %eax
	subq	%rax, %rdi
	movq	%rdi, (%rcx)
	movl	(%rdi), %eax
	testl	%eax, %eax
	je	LBB1_2

instead of:

LBB1_2:                                                     ## %bb1
	movl	(%rdi), %ecx
	subq	%rcx, %rdi
	movq	%rdi, (%rax)
	cmpl	$0, (%rdi)
	je	LBB1_2



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89978 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-26 23:41:07 +00:00
Chris Lattner
5d5261c819 Teach basicaa that x|c == x+c when the c bits of x are clear. This 
allows us to compile the example in readme.txt into:

LBB1_1:                                                     ## %bb
	movl	4(%rdx,%rax), %ecx
	movl	%ecx, %esi
	imull	(%rdx,%rax), %esi
	imull	%esi, %ecx
	movl	%esi, 8(%rdx,%rax)
	imull	%ecx, %esi
	movl	%ecx, 12(%rdx,%rax)
	movl	%esi, 16(%rdx,%rax)
	imull	%ecx, %esi
	movl	%esi, 20(%rdx,%rax)
	addq	$16, %rax
	cmpq	$4000, %rax
	jne	LBB1_1

instead of:

LBB1_1: 
	movl	(%rdx,%rax), %ecx
	imull	4(%rdx,%rax), %ecx
	movl	%ecx, 8(%rdx,%rax)
	imull	4(%rdx,%rax), %ecx
	movl	%ecx, 12(%rdx,%rax)
	imull	8(%rdx,%rax), %ecx
	movl	%ecx, 16(%rdx,%rax)
	imull	12(%rdx,%rax), %ecx
	movl	%ecx, 20(%rdx,%rax)
	addq	$16, %rax
	cmpq	$4000, %rax
	jne	LBB1_1

GCC (4.2) doesn't seem to be able to eliminate the loads in this 
testcase either, it generates:

L2:
	movl	(%rdx), %eax
	imull	4(%rdx), %eax
	movl	%eax, 8(%rdx)
	imull	4(%rdx), %eax
	movl	%eax, 12(%rdx)
	imull	8(%rdx), %eax
	movl	%eax, 16(%rdx)
	imull	12(%rdx), %eax
	movl	%eax, 20(%rdx)
	addl	$4, %ecx
	addq	$16, %rdx
	cmpl	$1002, %ecx
	jne	L2




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89952 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-26 16:26:43 +00:00
Chris Lattner
f6ac4d9dad teach basicaa that A[i] != A[i+1]. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89951 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-26 16:18:10 +00:00
Chris Lattner
9c6a0dcf0e update some notes slightly 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89913 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-26 01:51:18 +00:00
Nick Lewycky
93f9f7a440 Add a complex missed optimization opportunity I came across while investigating 
bug 5438.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88855 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-15 17:51:23 +00:00
Chris Lattner
fc926c2395 another const prop failure. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86848 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-11 17:54:02 +00:00
Chris Lattner
6fdfc9c630 add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86847 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-11 17:51:27 +00:00
Chris Lattner
1742498b5a add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86756 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-10 23:47:45 +00:00
Chris Lattner
b6ad9153dd I did this a week or two ago 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86754 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-10 23:40:49 +00:00
Nick Lewycky
f80fcd00b3 Improve tail call elimination to handle the switch statement. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86403 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-07 21:10:15 +00:00
Chris Lattner
6c9fab7404 add a note from PR5313 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86146 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-11-05 18:19:19 +00:00
Bill Wendling
c872e9c07d Add new note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85341 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-10-27 23:30:07 +00:00
Bill Wendling
5a56927345 Move and clarify note. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85334 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-10-27 22:48:31 +00:00
Chris Lattner
a1e1446056 this is done. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85041 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-10-25 06:17:51 +00:00
Chris Lattner
9ff9b34dd1 some stuff is done, we still have constantexpr simplification to do. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84943 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-10-23 07:00:55 +00:00
Chris Lattner
7d26443bb7 IPSCCP is missing stuff. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84725 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-10-21 01:10:37 +00:00
Chris Lattner
faa6adf67c add a note 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82442 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-09-21 06:04:07 +00:00
Chris Lattner
93c6c77340 one case handled, expanded another testcase inline. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82427 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-09-21 02:53:57 +00:00
Chris Lattner
c1491f3c47 update an entry, delete an entry which has been fixed. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82398 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-09-20 17:37:38 +00:00
Nick Lewycky
149cbc2a24 Peer through zext and sext to eliminate them when it is safe to do so. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82389 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-09-20 07:31:25 +00:00
Chris Lattner
c2b0d484dc add PR# 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81770 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-09-14 16:49:26 +00:00
Dan Gohman
9ca9daad21 Transform -X/C to X/-C, implementing a README.txt entry. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78812 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-08-12 16:37:02 +00:00
Eli Friedman
58bb61ae94 Remove a couple of already-implemented notes. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76631 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-07-21 20:05:43 +00:00
Nick Lewycky
f16120475e Move PR4517 to README.txt. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75098 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-07-09 04:03:30 +00:00
Dan Gohman
81db61a2e6 Factor the code for collecting IV users out of LSR into an IVUsers class, 
and generalize it so that it can be used by IndVarSimplify. Implement the
base IndVarSimplify transformation code using IVUsers. This removes
TestOrigIVForWrap and associated code, as ScalarEvolution now has enough
builtin overflow detection and folding logic to handle all the same cases,
and more. Run "opt -iv-users -analyze -disable-output" on your favorite
loop for an example of what IVUsers does.

This lets IndVarSimplify eliminate IV casts and compute trip counts in
more cases. Also, this happens to finally fix the remaining testcases
in PR1301.

Now that IndVarSimplify is being more aggressive, it occasionally runs
into the problem where ScalarEvolutionExpander's code for avoiding
duplicate expansions makes it difficult to ensure that all expanded
instructions dominate all the instructions that will use them. As a
temporary measure, IndVarSimplify now uses a FixUsesBeforeDefs function
to fix up instructions inserted by SCEVExpander. Fortunately, this code
is contained, and can be easily removed once a more comprehensive
solution is available.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71535 91177308-0d34-0410-b5e6-96231b3b80d8
 2009-05-12 02:17:14 +00:00