Commit Graph

24 Commits

Author SHA1 Message Date
Chris Lattner 445d8c6b50 fold comparisons of gep'd alloca points with null to false,
implementing PR12013.  We now compile the testcase to:

__Z4testv:                              ## @_Z4testv
## BB#0:                                ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit
	pushq	%rbx
	subq	$64, %rsp
	leaq	32(%rsp), %rbx
	movq	%rbx, (%rsp)
	leaq	64(%rsp), %rax
	movq	%rax, 16(%rsp)
	movl	$1, 32(%rsp)
	leaq	36(%rsp), %rax
	movq	%rax, 8(%rsp)
	leaq	(%rsp), %rdi
	callq	__Z1gRN4llvm11SmallVectorIiLj8EEE
	movq	(%rsp), %rdi
	cmpq	%rbx, %rdi
	je	LBB0_2
## BB#1:
	callq	_free
LBB0_2:                                 ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit
	addq	$64, %rsp
	popq	%rbx
	ret

instead of:

__Z4testv:                              ## @_Z4testv
## BB#0:
	pushq	%rbx
	subq	$64, %rsp
	xorl	%eax, %eax
	leaq	(%rsp), %rbx
	addq	$32, %rbx
	movq	%rbx, (%rsp)
	movq	%rbx, 8(%rsp)
	leaq	64(%rsp), %rcx
	movq	%rcx, 16(%rsp)
	je	LBB0_2
## BB#1:
	movl	$1, 32(%rsp)
	movq	%rbx, %rax
LBB0_2:                                 ## %_ZN4llvm15SmallVectorImplIiE9push_backERKi.exit
	addq	$4, %rax
	movq	%rax, 8(%rsp)
	leaq	(%rsp), %rdi
	callq	__Z1gRN4llvm11SmallVectorIiLj8EEE
	movq	(%rsp), %rdi
	cmpq	%rbx, %rdi
	je	LBB0_4
## BB#3:
	callq	_free
LBB0_4:                                 ## %_ZN4llvm11SmallVectorIiLj8EED1Ev.exit
	addq	$64, %rsp
	popq	%rbx
	ret

This doesn't shrink clang noticably though.

llvm-svn: 150944
2012-02-20 00:42:49 +00:00
Eli Friedman 952d1f9f40 Fix a rather nasty regression from r150690: LHS != RHS does not imply LHS->stripPointerCasts() != RHS->stripPointerCasts().
llvm-svn: 150863
2012-02-18 03:29:25 +00:00
Benjamin Kramer ea51f62e4b InstSimplify: Ignore pointer casts when constant folding compares between pointers.
llvm-svn: 150690
2012-02-16 13:49:39 +00:00
Duncan Sands 26641d7c02 Fix PR11948: the result type of an icmp may be a vector of boolean -
don't assume it is a boolean.

llvm-svn: 150247
2012-02-10 14:31:24 +00:00
Duncan Sands bf48ac622a Revert commit 149912 (lattner) and add a testcase that shows the problem (which
is that patterns no longer match for vectors of booleans, because you only get
ConstantDataVector when the vector element type is i8, i16, etc, not when it is
i1).  Original commit message:
Remove some dead code and tidy things up now that vectors use ConstantDataVector
instead of always using ConstantVector.

llvm-svn: 150246
2012-02-10 14:26:42 +00:00
Eli Friedman 0bae8b2cfb Fix code to match comment. Fixes PR11340, a regression from r143209.
llvm-svn: 144121
2011-11-08 21:08:02 +00:00
Duncan Sands 3d5692a475 Reapply commit 143214 with a fix: m_ICmp doesn't match conditions
with the given predicate, it matches any condition and returns the
predicate - d'oh!  Original commit message:
The expression icmp eq (select (icmp eq x, 0), 1, x), 0 folds to false.
Spotted by my super-optimizer in 186.crafty and 450.soplex.  We really
need a proper infrastructure for handling generalizations of this kind
of thing (which occur a lot), however this case is so simple that I decided
to go ahead and implement it directly.

llvm-svn: 143318
2011-10-30 19:56:36 +00:00
Eli Friedman 3af3c046a9 Revert r143214; it's breaking a bunch of stuff.
llvm-svn: 143265
2011-10-29 00:56:07 +00:00
Duncan Sands 280bc553b3 The expression icmp eq (select (icmp eq x, 0), 1, x), 0 folds to false.
Spotted by my super-optimizer in 186.crafty and 450.soplex.  We really
need a proper infrastructure for handling generalizations of this kind
of thing (which occur a lot), however this case is so simple that I decided
to go ahead and implement it directly.

llvm-svn: 143214
2011-10-28 19:01:20 +00:00
Duncan Sands 92af0a8a7f Fold icmp ugt (udiv X, Y), X to false. Spotted by my super-optimizer
in 186.crafty.

llvm-svn: 143209
2011-10-28 18:17:44 +00:00
Duncan Sands 7cb61e5a0e Reapply commit 143028 with a fix: the problem was casting a ConstantExpr Mul
using BinaryOperator (which only works for instructions) when it should have
been a cast to OverflowingBinaryOperator (which also works for constants).
While there, correct a few other dubious looking uses of BinaryOperator.
Thanks to Chad Rosier for the testcase.  Original commit message:
My super-optimizer noticed that we weren't folding this expression to
true: (x *nsw x) sgt 0, where x = (y | 1).  This occurs in 464.h264ref.

llvm-svn: 143125
2011-10-27 19:16:21 +00:00
Bob Wilson 1455ce27e4 Revert Duncan's r143028 expression folding which appears to be the culprit
behind a compile failure on 483.xalancbmk.

llvm-svn: 143102
2011-10-27 15:47:25 +00:00
Duncan Sands 1d2bb9882d My super-optimizer noticed that we weren't folding this expression to
true: (x *nsw x) sgt 0, where x = (y | 1).  This occurs in 464.h264ref.

llvm-svn: 143028
2011-10-26 15:31:51 +00:00
Nick Lewycky 56e99c7933 Remove bogus test: for all possible inputs of %X, the 'sub nsw' is guaranteed
to perform a signed wrap. Don't rely on any particular handling of that case.

llvm-svn: 135471
2011-07-19 08:22:57 +00:00
Benjamin Kramer 5acc751b6f Teach ComputeMaskedBits about sub nsw.
llvm-svn: 127548
2011-03-12 17:18:11 +00:00
Nick Lewycky cc79973856 Teach ComputeMaskedBits about nsw on add. I don't think there's anything we can
do with nuw here, but sub and mul should be given similar treatment.
Fixes PR9343 #15!

llvm-svn: 127463
2011-03-11 09:00:19 +00:00
Benjamin Kramer 1885d21700 Fix mistyped CHECK lines.
llvm-svn: 127366
2011-03-09 22:07:31 +00:00
Nick Lewycky 980104d1d6 Add another micro-optimization. Apologies for the lack of refactoring, but I
gave up when I realized I couldn't come up with a good name for what the
refactored function would be, to describe what it does.

This is PR9343 test12, which is test3 with arguments reordered. Whoops!

llvm-svn: 127318
2011-03-09 06:26:03 +00:00
Nick Lewycky 9719a719c7 Thread comparisons over udiv/sdiv/ashr/lshr exact and lshr nuw/nsw whenever
possible. This goes into instcombine and instsimplify because instsimplify
doesn't need to check hasOneUse since it returns (almost exclusively) constants.

This fixes PR9343 #4 #5 and #8!

llvm-svn: 127064
2011-03-05 05:19:11 +00:00
Nick Lewycky 41c529bd09 Revert broken srem logic from r126991.
llvm-svn: 127021
2011-03-04 19:26:08 +00:00
Nick Lewycky 8e3a79da9f Fold "icmp pred (srem X, Y), Y" like we do for urem. Handle signed comparisons
in the urem case, though not the other way around. This is enough to get #3 from
PR9343!

llvm-svn: 126991
2011-03-04 10:06:52 +00:00
Nick Lewycky 3cec6f5563 Teach instruction simplify to use constant ranges to solve problems of the form
"icmp pred %X, CI" and a number of examples where "%X = binop %Y, CI2".

Some of these cases (div and rem) used to make it through opt -O2, but the
others are probably now making code elsewhere redundant (probably instcombine).

llvm-svn: 126988
2011-03-04 07:00:57 +00:00
Nick Lewycky c9d20067cd Optimize "icmp pred (urem X, Y), Y" --> true/false depending on pred. There's
more work to do here, "icmp ult (urem X, 10), 11" doesn't optimize away yet.
Fixes example 3 from PR9343!

llvm-svn: 126741
2011-03-01 08:15:50 +00:00
Duncan Sands d114ab331c Teach instsimplify that X+Y>=X+Z is the same as Y>=Z if neither side overflows,
plus some variations of this.  According to my auto-simplifier this occurs a lot
but usually in combination with max/min idioms.  Because max/min aren't handled
yet this unfortunately doesn't have much effect in the testsuite.

llvm-svn: 125462
2011-02-13 17:15:40 +00:00