Commit Graph

119 Commits

Author SHA1 Message Date
Eric Christopher 04371b4f12 Remove this code for now. I have a better idea and will rewrite with
that in mind.

llvm-svn: 95402
2010-02-05 19:04:06 +00:00
Eric Christopher 107a1fbf61 Temporarily revert this since it appears to have caused a build
failure.

llvm-svn: 95294
2010-02-04 06:41:27 +00:00
Eric Christopher 42fa84a880 Rework constant expr and array handling for objectsize instcombining.
Fix bugs where we would compute out of bounds as in bounds, and where
we couldn't know that the linker could override the size of an array.

Add a few new testcases, change existing testcase to use a private
global array instead of extern.

llvm-svn: 95283
2010-02-04 02:55:34 +00:00
Eric Christopher f12e18db21 If we're dealing with a zero-length array, don't lower to any
particular size, we just don't know what the length is yet.

llvm-svn: 95266
2010-02-03 23:56:07 +00:00
Eric Christopher d86233c118 Recommit this, looks like it wasn't the cause.
llvm-svn: 95165
2010-02-03 00:21:58 +00:00
Eric Christopher e67d01a9a8 Hopefully temporarily revert this.
llvm-svn: 95154
2010-02-02 23:01:31 +00:00
Eric Christopher f9553572b7 Reformat my last patch slightly.
llvm-svn: 95147
2010-02-02 22:29:26 +00:00
Eric Christopher 4264e7e46f Re-add strcmp and known size object size checking optimization.
Passed bootstrap and nightly test run here.

llvm-svn: 95145
2010-02-02 22:10:43 +00:00
Chris Lattner 8e2c471614 don't turn (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B
for vectors.  Codegen is generating awful code or segfaulting
in various cases (e.g. PR6204).

llvm-svn: 95058
2010-02-02 02:43:51 +00:00
Dan Gohman 949458d014 LangRef.html says that inttoptr and ptrtoint always use zero-extension
when the cast is extending.

llvm-svn: 95046
2010-02-02 01:44:02 +00:00
Chris Lattner 9306ffa05a cleanups.
llvm-svn: 94995
2010-02-01 19:54:45 +00:00
Chris Lattner 846a52e228 fix rdar://7590304, a miscompilation of objc apps on arm. The caller
of objc message send was getting marked arm_apcscc, but the prototype
isn't.  This is fine at runtime because objcmsgsend is implemented in
assembly.  Only turn a mismatched caller and callee into 'unreachable'
if the callee is a definition.

llvm-svn: 94986
2010-02-01 18:11:34 +00:00
Chris Lattner 2cecedf081 fix rdar://7590304, an infinite loop in instcombine. In the invoke
case, instcombine can't zap the invoke for fear of changing the CFG.
However, we have to do something to prevent the next iteration of
instcombine from inserting another store -> undef before the invoke
thereby getting into infinite iteration between dead store elim and
store insertion.

Just zap the callee to null, which will prevent the next iteration
from doing anything.

llvm-svn: 94985
2010-02-01 18:04:58 +00:00
Eli Friedman a2cc2875fc Simplify/generalize the xor+add->sign-extend instcombine.
llvm-svn: 94943
2010-01-31 04:29:12 +00:00
Eli Friedman 37a8197b61 Add a small transform: transform -(X<<Y) to (-X<<Y) when the shift has a single
use and X is free to negate.

llvm-svn: 94941
2010-01-31 02:30:23 +00:00
Bob Wilson 56600a15ad Check alignment of loads when deciding whether it is safe to execute them
unconditionally.  Besides checking the offset, also check that the underlying
object is aligned as much as the load itself.

llvm-svn: 94875
2010-01-30 04:42:39 +00:00
Bob Wilson 4b71b6c179 Use more specific types to avoid casts. No functionality change.
llvm-svn: 94863
2010-01-30 00:41:10 +00:00
Bob Wilson 1b8453067b Preserve load alignment in instcombine transformations. I've been unable to
create a testcase where this matters.  The select+load transformation only
occurs when isSafeToLoadUnconditionally is true, and in those situations,
instcombine also changes the underlying objects to be aligned.  This seems
like a good idea regardless, and I've verified that it doesn't pessimize
the subsequent realignment.

llvm-svn: 94850
2010-01-29 22:39:21 +00:00
Eric Christopher 5a0e174863 Revert my last couple of patches. They appear to have broken bison.
llvm-svn: 94841
2010-01-29 21:16:24 +00:00
Bob Wilson 7c42b9d51e 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.

llvm-svn: 94829
2010-01-29 19:19:08 +00:00
Duncan Sands c8a3e56870 Having RHSKnownZero and RHSKnownOne be alternative names for KnownZero and KnownOne
(via APInt &RHSKnownZero = KnownZero, etc) seems dangerous and confusing to me: it
is easy not to notice this, and then wonder why KnownZero/RHSKnownZero changed
underneath you when you modified RHSKnownZero/KnownZero etc.  So get rid of this.
No intended functionality change (tested with "make check" + llvm-gcc bootstrap).

llvm-svn: 94802
2010-01-29 06:18:46 +00:00
Eric Christopher 997f7ca8c5 Add constant support to object size handling and remove default
lowering. We'll either figure it out, or not and be lowered by
SelectionDAGBuild.

Add test.

llvm-svn: 94775
2010-01-29 01:09:57 +00:00
Duncan Sands 3a48b87c54 Fix PR6165. The bug was that LHSKnownZero was being and'd with DemandedMask
when it should have been and'd with LowBits.  Fix that and while there beef
up the logic in the case of a negative LHS.

llvm-svn: 94745
2010-01-28 17:22:42 +00:00
Chris Lattner 823aed16f9 make -fno-rtti the default unless a directory builds with REQUIRES_RTTI.
llvm-svn: 94378
2010-01-24 20:43:08 +00:00
Chris Lattner 1b35bbe813 change the canonical form of "cond ? -1 : 0" to be
"sext cond" instead of a select.  This simplifies some instcombine
code, matches the policy for zext (cond ? 1 : 0 -> zext), and allows
us to generate better code for a testcase on ppc.

llvm-svn: 94339
2010-01-24 00:09:49 +00:00
Chris Lattner e112ff64c5 fix a potential overflow issue Eli pointed out.
llvm-svn: 94336
2010-01-23 23:31:46 +00:00
Chris Lattner 249da5cb73 implement a simple instcombine xform that has been in the
readme forever.

llvm-svn: 94318
2010-01-23 18:49:30 +00:00
Victor Hernandez 5f8c8c034a Keep ignoring pointer-to-pointer bitcasts
llvm-svn: 94194
2010-01-22 19:05:05 +00:00
Chris Lattner 7ba0661f27 Stop building RTTI information for *most* llvm libraries. Notable
missing ones are libsupport, libsystem and libvmcore.  libvmcore is
currently blocked on bugpoint, which uses EH.  Once it stops using
EH, we can switch it off.

This #if 0's out 3 unit tests, because gtest requires RTTI information.
Suggestions welcome on how to fix this.

llvm-svn: 94164
2010-01-22 06:49:46 +00:00
Victor Hernandez 5f5abd598c No need to look through bitcasts for DbgInfoIntrinsic
llvm-svn: 94112
2010-01-21 23:07:15 +00:00
Chris Lattner 18f49ce2d3 optimize ~(~X >>s Y) --> (X >>s Y), patch by Edmund Grimley
Evans!

llvm-svn: 93884
2010-01-19 18:16:19 +00:00
Eric Christopher 84bd316bd6 Fix comment.
llvm-svn: 93831
2010-01-19 01:20:15 +00:00
Chris Lattner 43f2fa6201 my instcombine transformations to make extension elimination more
aggressive changed the canonical form from sext(trunc(x)) to ashr(lshr(x)),
make sure to transform a couple more things into that canonical form,
and catch a case where we missed turning zext/shl/ashr into a single sext.

llvm-svn: 93787
2010-01-18 22:19:16 +00:00
Owen Anderson fa1edea9ce Fix comment.
llvm-svn: 93679
2010-01-17 06:49:03 +00:00
Bill Wendling ad7a5b07a7 When the visitSub method was split into visitSub and visitFSub, this xform was
added to the FSub version. However, the original version of this xform guarded
against doing this for floating point (!Op0->getType()->isFPOrFPVector()).

This is causing LLVM to perform incorrect xforms for code like:

void func(double *rhi, double *rlo, double xh, double xl, double yh, double yl){
  double mh, ml;
  double c = 134217729.0;
  double up, u1, u2, vp, v1, v2;
        
  up = xh*c;
  u1 = (xh - up) + up;
  u2 = xh - u1;
        
  vp = yh*c;
  v1 = (yh - vp) + vp;
  v2 = yh - v1;
        
  mh = xh*yh;
  ml = (((u1*v1 - mh) + (u1*v2)) + (u2*v1)) + (u2*v2);
  ml += xh*yl + xl*yh;
        
  *rhi = mh + ml;
  *rlo = (mh - (*rhi)) + ml;
}

The last line was optimized away, but rl is intended to be the difference
between the infinitely precise result of mh + ml and after it has been rounded
to double precision.

llvm-svn: 93369
2010-01-13 23:23:17 +00:00
Chris Lattner d1a3efedd8 reenable the piece that turns trunc(zext(x)) -> x even if zext has multiple uses,
codegen has no apparent problem with the trunc version of this, because it turns
into a simple subreg idiom

llvm-svn: 93202
2010-01-11 22:49:40 +00:00
Chris Lattner a6b1356cf9 Disable folding sext(trunc(x)) -> x (and other similar cast/cast cases) when the
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
2010-01-11 22:45:25 +00:00
Chris Lattner 9518869423 add one more bitfield optimization, allowing clang to generate
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
2010-01-11 06:55:24 +00:00
Chris Lattner 0a85420409 Extend CanEvaluateZExtd to handle and/or/xor more aggressively in the
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
2010-01-11 04:05:13 +00:00
Chris Lattner 12bd8992b3 Remove the dead TD argument to CanEvaluateZExtd, and add a
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
2010-01-11 03:32:00 +00:00
Chris Lattner 172630abd2 improve comments, remove dead TD argument to CanEvaluateSExtd.
llvm-svn: 93143
2010-01-11 02:43:35 +00:00
Chris Lattner 7dd540ee24 teach sext optimization to handle truncs from types that are not
the dest of the sext.

llvm-svn: 93128
2010-01-10 20:30:41 +00:00
Chris Lattner 39d2daa94c teach zext optimization how to deal with truncs that don't come from
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
2010-01-10 20:25:54 +00:00
Chris Lattner 1a05fddcdc simplify CanEvaluateSExtd to return a bool now that we have a
simpler profitability predicate.

llvm-svn: 93111
2010-01-10 07:57:20 +00:00
Chris Lattner d7816780e2 the NumCastsRemoved argument to CanEvaluateSExtd is dead, remove it.
llvm-svn: 93110
2010-01-10 07:42:21 +00:00
Chris Lattner 2fff10c424 now that the cost model has changed, we can always consider
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
2010-01-10 07:40:50 +00:00
Chris Lattner d8509424a4 change the preferred canonical form for a sign extension to be
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
2010-01-10 07:08:30 +00:00
Chris Lattner 2b459fe7e1 fix indentation of switch statements, no functionality change.
llvm-svn: 93106
2010-01-10 06:59:55 +00:00
Chris Lattner 127bbc715e fix pasto that broke bootstrap.
llvm-svn: 93105
2010-01-10 06:50:04 +00:00
Chris Lattner b7be7cc486 simplify CanEvaluateZExtd now that we don't care about the number of
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
2010-01-10 02:50:04 +00:00