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2285 Commits

Author SHA1 Message Date
Eli Friedman 716c10c01e Fix for bug 1996: optimize out loads of undef. This code basically just 
checks for a malloc/alloca immediately followed by a load.

llvm-svn: 47006
 2008-02-12 12:08:14 +00:00
Chris Lattner dcddd64424 Fix scalarrepl to not 'miscompile' undefined code, part #2. 
This fixes the store case, my previous patch just fixed the load
case.  rdar://5707076.

llvm-svn: 46932
 2008-02-10 19:05:37 +00:00
Devang Patel 26f75e2576 Fix PR 1995. 
llvm-svn: 46898
 2008-02-08 22:49:13 +00:00
Bill Wendling c676a0329c Temporarily reverting: 
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20080128/057882.html

This is causing a miscompilation on PPC G5 and just now seeing it on iMac x86-64.

llvm-svn: 46822
 2008-02-06 20:03:07 +00:00
Chris Lattner 682a7dc653 Fix a bug compiling PR1978 (perhaps not the only one though) which 
was incorrectly simplifying "x == (gep x, 1, i)" into false, even 
though i could be negative.  As it turns out, all the code to 
handle this already existed, we just need to disable the incorrect
optimization case and let the general case handle it.

llvm-svn: 46739
 2008-02-05 04:45:32 +00:00
Owen Anderson a82c9931f4 Be more precise when eliminating pointers bue to memcpy's. This allows more 
stores to be deleted in some cases.

llvm-svn: 46694
 2008-02-04 04:53:00 +00:00
Owen Anderson c4a7c41869 Allow GVN to hack on memcpy's, making them open to further optimization. 
llvm-svn: 46693
 2008-02-04 02:59:58 +00:00
Nick Lewycky 3b59214320 There are some cases where icmp(add) can be folded into a new icmp. Handle them. 
llvm-svn: 46687
 2008-02-03 16:33:09 +00:00
Nick Lewycky c7a4ba044b Hack on vectors too. 
llvm-svn: 46684
 2008-02-03 08:19:11 +00:00
Nick Lewycky e6e3a7f6ea Fold away one multiply in instcombine. This would normally be caught in 
reassociate anyways, but they could be generated during instcombine's run.

llvm-svn: 46683
 2008-02-03 07:42:09 +00:00
Nick Lewycky 6b016703a9 Remove a couple more cases of "getNumUses() == 0". No need to walk the linked 
list just to see if whether the list is empty.

llvm-svn: 46555
 2008-01-30 08:01:28 +00:00
Nick Lewycky 625e89c8b0 Use empty() instead of comparing size() with zero. 
llvm-svn: 46554
 2008-01-30 07:54:16 +00:00
Nick Lewycky 0e3a5cb14a Don't DCE FreeInst's. We were using those! Patch from Owen Anderson. 
llvm-svn: 46553
 2008-01-30 07:45:37 +00:00
Owen Anderson 4e4b116750 Make DSE much more aggressive by performing DCE earlier. Update a testcase to reflect this increased aggressiveness. 
llvm-svn: 46542
 2008-01-30 01:24:47 +00:00
Chris Lattner b9e5b8fb9e Fix a bug where scalarrepl would discard offset if type would match. 
In practice this can only happen on code with already undefined behavior, 
but this is still a good thing to handle correctly.

llvm-svn: 46539
 2008-01-30 00:39:15 +00:00
Dan Gohman 70de4cb1cd Use empty() instead of comparing size() with zero. 
llvm-svn: 46514
 2008-01-29 13:02:09 +00:00
Chris Lattner 17819d971e eliminate additions of 0.0 when they are obviously dead. This has to be careful to 
avoid turning -0.0 + 0.0 -> -0.0 which is incorrect.

llvm-svn: 46499
 2008-01-29 06:52:45 +00:00
Owen Anderson 48d37806e2 Add support for eliminating memcpy's at the end of functions. Also fix some errors I noticed in 
the handling of eliminating stores to byval arguments.

llvm-svn: 46494
 2008-01-29 06:18:36 +00:00
Devang Patel 67fa0521b6 Filter loops that subtract induction variables. 
These loops are not yet handled.

Fix PR 1912.

llvm-svn: 46484
 2008-01-29 02:20:41 +00:00
Nick Lewycky 8ea81e8ba4 Handle some more combinations of extend and icmp. Fixes PR1940. 
llvm-svn: 46431
 2008-01-28 03:48:02 +00:00
Chris Lattner 710b441174 Fix PR1932 by disabling an xform invalid for fdiv. 
llvm-svn: 46429
 2008-01-28 00:58:18 +00:00
Chris Lattner 1b706dd680 Fix PR1938 by forcing the code that uses an undefined value to branch one 
way or the other.  Rewriting the code itself prevents subsequent analysis
passes from making contradictory conclusions about the code that could 
cause an infeasible path to be made feasible.

llvm-svn: 46427
 2008-01-28 00:32:30 +00:00
Nick Lewycky efb16f7057 Be more careful modifying the use_list while also iterating through it. 
llvm-svn: 46417
 2008-01-27 18:35:00 +00:00
Bill Wendling 60361a16f8 The CorrelatedExpressionElimination pass is known to be buggy. Remove it. 
This fixes PR1769.

llvm-svn: 46408
 2008-01-27 06:11:41 +00:00
Chris Lattner fa1e7eef30 Fold fptrunc(add (fpextend x), (fpextend y)) -> add(x,y), as GCC does. 
llvm-svn: 46406
 2008-01-27 05:29:54 +00:00
Bill Wendling 5079483957 If there are no machine instructions emitted for a function, then insert 
a "nop" instruction so that we don't have the function's label associated
with something that it's not supposed to be associated with.

llvm-svn: 46394
 2008-01-26 06:51:24 +00:00
Bill Wendling 0862e3421d If we have a function like this: 
void bork() {
  int *address = 0;
  *address = 0;
}

It's compiled into LLVM code that looks like this:

define void @bork() noreturn nounwind  {
entry:
        unreachable
}

This is bad on some platforms (like PPC) because it will generate the label for
the function but no body. The label could end up being associated with some
non-code related stuff, like a section. This places a "trap" instruction if the
SimplifyCFG pass removed all code from the function leaving only one
"unreachable" instruction.

llvm-svn: 46387
 2008-01-26 01:43:44 +00:00
Owen Anderson 6af19fd1e2 DeadStoreElimination can treat byval parameters as if there were alloca's for the purpose of removing end-of-function stores. 
llvm-svn: 46351
 2008-01-25 10:10:33 +00:00
Nick Lewycky f069264164 Enable the fix I just checked in, silly me. 
llvm-svn: 46247
 2008-01-22 05:42:02 +00:00
Nick Lewycky 78712e5b59 Multiply can be evaluated in a different type, so long as the target type has 
a smaller bitwidth.

llvm-svn: 46244
 2008-01-22 05:08:48 +00:00
Duncan Sands afa84da4e0 Make sure the caller doesn't use freed memory. 
Fixes PR1935.

llvm-svn: 46203
 2008-01-20 16:51:46 +00:00
Duncan Sands fe3bef091f Initializing an unsigned with ~0UL causes the compiler 
to complain on x86-64 (gcc 4.1).  Use ~0U instead.

llvm-svn: 46197
 2008-01-20 10:49:23 +00:00
Duncan Sands b5ca2e9fcb I noticed that the trampoline straightening transformation could 
drop attributes on varargs call arguments.  Also, it could generate
invalid IR if the transformed call already had the 'nest' attribute
somewhere (this can never happen for code coming from llvm-gcc,
but it's a theoretical possibility).  Fix both problems.

llvm-svn: 45973
 2008-01-14 19:52:09 +00:00
Chris Lattner 92bd785323 Turn a memcpy from a double* into a load/store of double instead of 
a load/store of i64.  The later prevents promotion/scalarrepl of the
source and dest in many cases.

This fixes the 300% performance regression of the byval stuff on 
stepanov_v1p2.

llvm-svn: 45945
 2008-01-14 00:28:35 +00:00
Chris Lattner 57974c8d51 factor memcpy/memmove simplification out to its own SimplifyMemTransfer 
method, no functionality change.

llvm-svn: 45944
 2008-01-13 23:50:23 +00:00
Chris Lattner 8c5cdddfb9 simplify some code. If we can infer alignment for source and dest that are 
greater than memcpy alignment, and if we lower to load/store, use the best 
alignment info we have.

llvm-svn: 45943
 2008-01-13 22:30:28 +00:00
Chris Lattner 5a86612d3f simplify some code by adding a InsertBitCastBefore method, 
make memmove->memcpy conversion a bit simpler.

llvm-svn: 45942
 2008-01-13 22:23:22 +00:00
Chris Lattner 5bc253c8f2 Fix PR1907, a nasty miscompilation because instcombine didn't 
realize that ne & sgt  was a signed comparison (it was only 
looking at whether the left compare was signed).

llvm-svn: 45937
 2008-01-13 20:59:02 +00:00
Duncan Sands 781f6549db When turning a call to a bitcast function into a direct call, 
if this becomes a varargs call then deal correctly with any
parameter attributes on the newly vararg call arguments.

llvm-svn: 45931
 2008-01-13 08:02:44 +00:00
Chris Lattner 2940c5c56d Implement PR1795, an instcombine hack for forming GEPs with integer pointer arithmetic. 
llvm-svn: 45745
 2008-01-08 07:23:51 +00:00
Duncan Sands b18c30acec Small cleanup for handling of type/parameter attribute 
incompatibility.

llvm-svn: 45704
 2008-01-07 17:16:06 +00:00
Gordon Henriksen efb08802ec Deleting an empty file. Thanks, /usr/bin/patch! 
llvm-svn: 45675
 2008-01-07 02:29:04 +00:00
Gordon Henriksen 6047b6e140 With this patch, the LowerGC transformation becomes the 
ShadowStackCollector, which additionally has reduced overhead with
no sacrifice in portability.

Considering a function @fun with 8 loop-local roots,
ShadowStackCollector introduces the following overhead
(x86):

; shadowstack prologue
        movl    L_llvm_gc_root_chain$non_lazy_ptr, %eax
        movl    (%eax), %ecx
        movl    $___gc_fun, 20(%esp)
        movl    $0, 24(%esp)
        movl    $0, 28(%esp)
        movl    $0, 32(%esp)
        movl    $0, 36(%esp)
        movl    $0, 40(%esp)
        movl    $0, 44(%esp)
        movl    $0, 48(%esp)
        movl    $0, 52(%esp)
        movl    %ecx, 16(%esp)
        leal    16(%esp), %ecx
        movl    %ecx, (%eax)

; shadowstack loop overhead
        (none)

; shadowstack epilogue
        movl    48(%esp), %edx
        movl    %edx, (%ecx)

; shadowstack metadata
        .align  3
___gc_fun:                              # __gc_fun
        .long   8
        .space  4

In comparison to LowerGC:

; lowergc prologue
        movl    L_llvm_gc_root_chain$non_lazy_ptr, %eax
        movl    (%eax), %ecx
        movl    %ecx, 48(%esp)
        movl    $8, 52(%esp)
        movl    $0, 60(%esp)
        movl    $0, 56(%esp)
        movl    $0, 68(%esp)
        movl    $0, 64(%esp)
        movl    $0, 76(%esp)
        movl    $0, 72(%esp)
        movl    $0, 84(%esp)
        movl    $0, 80(%esp)
        movl    $0, 92(%esp)
        movl    $0, 88(%esp)
        movl    $0, 100(%esp)
        movl    $0, 96(%esp)
        movl    $0, 108(%esp)
        movl    $0, 104(%esp)
        movl    $0, 116(%esp)
        movl    $0, 112(%esp)

; lowergc loop overhead
        leal    44(%esp), %eax
        movl    %eax, 56(%esp)
        leal    40(%esp), %eax
        movl    %eax, 64(%esp)
        leal    36(%esp), %eax
        movl    %eax, 72(%esp)
        leal    32(%esp), %eax
        movl    %eax, 80(%esp)
        leal    28(%esp), %eax
        movl    %eax, 88(%esp)
        leal    24(%esp), %eax
        movl    %eax, 96(%esp)
        leal    20(%esp), %eax
        movl    %eax, 104(%esp)
        leal    16(%esp), %eax
        movl    %eax, 112(%esp)

; lowergc epilogue
        movl    48(%esp), %edx
        movl    %edx, (%ecx)

; lowergc metadata
        (none)

llvm-svn: 45670
 2008-01-07 01:30:53 +00:00
Duncan Sands 404eb05247 The transform that tries to turn calls to bitcast functions into 
direct calls bails out unless caller and callee have essentially
equivalent parameter attributes.  This is illogical - the callee's
attributes should be of no relevance here.  Rework the logic, which
incidentally fixes a crash when removed arguments have attributes.

llvm-svn: 45658
 2008-01-06 18:27:01 +00:00
Duncan Sands 55e5090fe8 When transforming a call to a bitcast function into 
a direct call with cast parameters and cast return
value (if any), instcombine was prepared to cast any
non-void return value into any other, whether castable
or not.  Add a new predicate for testing whether casting
is valid, and check it both for the return value and
(as a cleanup) for the parameters.

llvm-svn: 45657
 2008-01-06 10:12:28 +00:00
Chris Lattner e666bc272d remove a couple more unsafe xforms in the face of overflow. 
llvm-svn: 45613
 2008-01-05 01:22:42 +00:00
Chris Lattner db026d703b remove the (x-y) < 0 comparison xform, it miscompiles 
things that are not equality comparisons, for example:
   (2147479553+4096)-2147479553 < 0    !=   (2147479553+4096) < 2147479553

llvm-svn: 45612
 2008-01-05 01:18:20 +00:00
Wojciech Matyjewicz 30e434569e fix typo 
llvm-svn: 45594
 2008-01-04 20:02:18 +00:00
Chris Lattner f3ebc3f3d2 Remove attribution from file headers, per discussion on llvmdev. 
llvm-svn: 45418
 2007-12-29 20:36:04 +00:00
Chris Lattner a087a8d2ce remove attribution from lib Makefiles. 
llvm-svn: 45415
 2007-12-29 20:09:26 +00:00