After r289755, the AssumptionCache is no longer needed. Variables affected by
assumptions are now found by using the new operand-bundle-based scheme. This
new scheme is more computationally efficient, and also we need much less
code...
llvm-svn: 289756
Reverts r289412. It caused an OOB PHI operand access in instcombine when
ASan is enabled. Reduction in progress.
Also reverts "[SCEVExpander] Add a test case related to r289412"
llvm-svn: 289453
SCEVExpand computes the insertion point for the components of a SCEV to be code
generated. When it comes to generating code for a division, SCEVexpand would
not be able to check (at compilation time) all the conditions necessary to avoid
a division by zero. The patch disables hoisting of expressions containing
divisions by anything other than non-zero constants in order to avoid hoisting
these expressions past conditions that should hold before doing the division.
The patch passes check-all on x86_64-linux.
Differential Revision: https://reviews.llvm.org/D27216
llvm-svn: 289412
This is NFC today, but won't be once D27216 (or an equivalent patch) is
in.
This change fixes a design problem in SCEVExpander -- it relied on a
hoisting optimization to generate correct code for add recurrences.
This meant changing the hoisting optimization to not kick in under
certain circumstances (to avoid speculating faulting instructions, say)
would break correctness.
The fix is to make the correctness requirements explicit, and have it
not rely on the hoisting optimization for correctness.
llvm-svn: 289397
value is a pointer.
This patch is to fix PR30213. When expanding an expr based on ValueOffsetPair,
if the value is of pointer type, we can only create a getelementptr instead
of sub expr.
Differential Revision: https://reviews.llvm.org/D24088
llvm-svn: 281439
Summary:
This is an extension of the fix in r271424. That fix dealt with builder
insert points being moved by SCEV expansion, but only for the lifetime
of the expand call. This change modifies the interface so that LSR can
safely call expand multiple times at the same insert point and do the
right thing if one of the expansions decides to move the original insert
point.
This is a fix for PR28719.
Reviewers: sanjoy
Subscribers: llvm-commits, mcrosier, mzolotukhin
Differential Revision: https://reviews.llvm.org/D23342
llvm-svn: 278413
The patch is to fix the bug in PR28705. It was caused by setting wrong return
value for SCEVExpander::findExistingExpansion. The return values of findExistingExpansion
have different meanings when the function is used in different ways so it is easy to make
mistake. The fix creates two new interfaces to replace SCEVExpander::findExistingExpansion,
and specifies where each interface is expected to be used.
Differential Revision: https://reviews.llvm.org/D22942
llvm-svn: 278161
The fix for PR28705 will be committed consecutively.
In D12090, the ExprValueMap was added to reuse existing value during SCEV expansion.
However, const folding and sext/zext distribution can make the reuse still difficult.
A simplified case is: suppose we know S1 expands to V1 in ExprValueMap, and
S1 = S2 + C_a
S3 = S2 + C_b
where C_a and C_b are different SCEVConstants. Then we'd like to expand S3 as
V1 - C_a + C_b instead of expanding S2 literally. It is helpful when S2 is a
complex SCEV expr and S2 has no entry in ExprValueMap, which is usually caused
by the fact that S3 is generated from S1 after const folding.
In order to do that, we represent ExprValueMap as a mapping from SCEV to
ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a} into the
ExprValueMap when we create SCEV for V1. When S3 is expanded, it will first
expand S2 to V1 - C_a because of S2->{V1, C_a} in the map, then expand S3 to
V1 - C_a + C_b.
Differential Revision: https://reviews.llvm.org/D21313
llvm-svn: 278160
In D12090, the ExprValueMap was added to reuse existing value during SCEV expansion.
However, const folding and sext/zext distribution can make the reuse still difficult.
A simplified case is: suppose we know S1 expands to V1 in ExprValueMap, and
S1 = S2 + C_a
S3 = S2 + C_b
where C_a and C_b are different SCEVConstants. Then we'd like to expand S3 as
V1 - C_a + C_b instead of expanding S2 literally. It is helpful when S2 is a
complex SCEV expr and S2 has no entry in ExprValueMap, which is usually caused
by the fact that S3 is generated from S1 after const folding.
In order to do that, we represent ExprValueMap as a mapping from SCEV to
ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a} into the
ExprValueMap when we create SCEV for V1. When S3 is expanded, it will first
expand S2 to V1 - C_a because of S2->{V1, C_a} in the map, then expand S3 to
V1 - C_a + C_b.
Differential Revision: https://reviews.llvm.org/D21313
llvm-svn: 276136
Summary:
Make sure that the SCEVExpander Builder insert point and any
saved/restored insert points are kept consistent (i.e. their Instruction
and BasicBlock match) when moving instructions in SCEVExpander.
This fixes an issue triggered by
http://reviews.llvm.org/D18001 [LSR] Create fewer redundant instructions.
Test case will be added in reapply commit of above change:
http://reviews.llvm.org/D18480 Reapply [LSR] Create fewer redundant instructions.
Reviewers: sanjoy
Subscribers: mzolotukhin, sanjoy, qcolombet, mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D20703
llvm-svn: 271424
SCEVExpander::replaceCongruentIVs assumes the backedge value of an
SCEV-analysable PHI to always be an instruction, when this is not
necessarily true. For now address this by bailing out of the
optimization if the backedge value of the PHI is a non-Instruction.
llvm-svn: 269213
`SCEVExpander::replaceCongruentIVs` bypasses `hoistIVInc` if both the
original and the isomorphic increments are PHI nodes. Doing this can
break SSA if the isomorphic increment is not dominated by the original
increment. Get rid of the bypass, and let `hoistIVInc` do the right
thing.
Fixes PR27232 (compile time crash/hang).
llvm-svn: 269212
Summary:
This implements a new method of run-time checking the NoWrap
SCEV predicates, which should be easier to optimize and nicer
for targets that don't correctly handle multiplication/addition
of large integer types (like i128).
If the AddRec is {a,+,b} and the backedge taken count is c,
the idea is to check that |b| * c doesn't have unsigned overflow,
and depending on the sign of b, that:
a + |b| * c >= a (b >= 0) or
a - |b| * c <= a (b <= 0)
where the comparisons above are signed or unsigned, depending on
the flag that we're checking.
The advantage of doing this is that we avoid extending to a larger
type and we avoid the multiplication of large types (multiplying
i128 can be expensive).
Reviewers: sanjoy
Subscribers: llvm-commits, mzolotukhin
Differential Revision: http://reviews.llvm.org/D19266
llvm-svn: 267389
This re-commits r265535 which was reverted in r265541 because it
broke the windows bots. The problem was that we had a PointerIntPair
which took a pointer to a struct allocated with new. The problem
was that new doesn't provide sufficient alignment guarantees.
This pattern was already present before r265535 and it just happened
to work. To fix this, we now separate the PointerToIntPair from the
ExitNotTakenInfo struct into a pointer and a bool.
Original commit message:
Summary:
When the backedge taken codition is computed from an icmp, SCEV can
deduce the backedge taken count only if one of the sides of the icmp
is an AddRecExpr. However, due to sign/zero extensions, we sometimes
end up with something that is not an AddRecExpr.
However, we can use SCEV predicates to produce a 'guarded' expression.
This change adds a method to SCEV to get this expression, and the
SCEV predicate associated with it.
In HowManyGreaterThans and HowManyLessThans we will now add a SCEV
predicate associated with the guarded backedge taken count when the
analyzed SCEV expression is not an AddRecExpr. Note that we only do
this as an alternative to returning a 'CouldNotCompute'.
We use new feature in Loop Access Analysis and LoopVectorize to analyze
and transform more loops.
Reviewers: anemet, mzolotukhin, hfinkel, sanjoy
Subscribers: flyingforyou, mcrosier, atrick, mssimpso, sanjoy, mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D17201
llvm-svn: 265786
Daniel Jasper
Hal Finkel
Reid Kleckner
Sebastian Pop
Sanjoy Das
Simon Pilgrim
Nico Weber
Wei Mi
David Majnemer
Geoff Berry
Hans Wennborg
Keno Fischer
Patrik Hagglund
Silviu Baranga
Nick Lewycky