What follows bellow is a correctness proof of the transform using CVC3.
$ < t.cvc
A, B : BITVECTOR(32);
QUERY BVPLUS(32, A & B, A | B) = BVPLUS(32, A, B);
$ cvc3 < t.cvc
Valid.
llvm-svn: 215400
We can only propagate the nsw bits if both subtraction instructions are
marked with the appropriate bit.
N.B. We only propagate the nsw bit in InstCombine because the nuw case
is already handled in InstSimplify.
This fixes PR20189.
llvm-svn: 214385
While we can already transform A | (A ^ B) into A | B, things get bad
once we have (A ^ B) | (A ^ B ^ Cst) because reassociation will morph
this into (A ^ B) | ((A ^ Cst) ^ B). Our existing patterns fail once
this happens.
To fix this, we add a new pattern which looks through the tree of xor
binary operators to see that, in fact, there exists a redundant xor
operation.
What follows bellow is a correctness proof of the transform using CVC3.
$ cat t.cvc
A, B, C : BITVECTOR(64);
QUERY BVXOR(A, B) | BVXOR(BVXOR(B, C), A) = BVXOR(A, B) | C;
QUERY BVXOR(BVXOR(A, C), B) | BVXOR(A, B) = BVXOR(A, B) | C;
QUERY BVXOR(A, B) & BVXOR(BVXOR(B, C), A) = BVXOR(A, B) & ~C;
QUERY BVXOR(BVXOR(A, C), B) & BVXOR(A, B) = BVXOR(A, B) & ~C;
$ cvc3 < t.cvc
Valid.
Valid.
Valid.
Valid.
llvm-svn: 214342
In order to enable the preservation of noalias function parameter information
after inlining, and the representation of block-level __restrict__ pointer
information (etc.), additional kinds of aliasing metadata will be introduced.
This metadata needs to be carried around in AliasAnalysis::Location objects
(and MMOs at the SDAG level), and so we need to generalize the current scheme
(which is hard-coded to just one TBAA MDNode*).
This commit introduces only the necessary refactoring to allow for the
introduction of other aliasing metadata types, but does not actually introduce
any (that will come in a follow-up commit). What it does introduce is a new
AAMDNodes structure to hold all of the aliasing metadata nodes associated with
a particular memory-accessing instruction, and uses that structure instead of
the raw MDNode* in AliasAnalysis::Location, etc.
No functionality change intended.
llvm-svn: 213859
It handles the errors which were seen in PR19958 where wrong code was being emitted due to earlier patch.
Added code for lshr as well as non-exact right shifts.
It implements :
(icmp eq/ne (ashr/lshr const2, A), const1)" ->
(icmp eq/ne A, Log2(const2/const1)) ->
(icmp eq/ne A, Log2(const2) - Log2(const1))
Differential Revision: http://reviews.llvm.org/D4068
llvm-svn: 213678
"((~A & B) | A) -> (A | B)" and "((A & B) | ~A) -> (~A | B)"
Original Patch credit to Ankit Jain !!
Differential Revision: http://reviews.llvm.org/D4591
llvm-svn: 213676
Summary: This patch introduces two new iterator ranges and updates existing code to use it. No functional change intended.
Test Plan: All tests (make check-all) still pass.
Reviewers: dblaikie
Reviewed By: dblaikie
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D4481
llvm-svn: 213474
Refactor code, no functionality change, test case moved from instcombine to instsimplify.
Differential Revision: http://reviews.llvm.org/D4102
llvm-svn: 213231
In the original version of the patch the behaviour was like described in
the comment. This behaviour was changed before committing it without
updating the comment.
llvm-svn: 213117
Fix a crash in `InstCombiner::Descale()` when a multiply-by-zero gets
created as an argument to a GEP partway through an iteration, causing
-instcombine to optimize the GEP before the multiply.
rdar://problem/17615671
llvm-svn: 212742
isSafeToSpeculativelyExecute can optionally take a DataLayout pointer. In the
past, this was mainly used to make better decisions regarding divisions known
not to trap, and so was not all that important for users concerned with "cheap"
instructions. However, now it also helps look through bitcasts for
dereferencable loads, and will also be important if/when we add a
dereferencable pointer attribute.
This is some initial work to feed a DataLayout pointer through to callers of
isSafeToSpeculativelyExecute, generally where one was already available.
llvm-svn: 212720
In PR20059 ( http://llvm.org/pr20059 ), instcombine eliminates shuffles that are necessary before performing an operation that can trap (srem).
This patch calls isSafeToSpeculativelyExecute() and bails out of the optimization in SimplifyVectorOp() if needed.
Differential Revision: http://reviews.llvm.org/D4424
llvm-svn: 212629
This patch reduces the stack memory consumption of the InstCombine
function "isOnlyCopiedFromConstantGlobal() ", that in certain conditions
could overflow the stack because of excessive recursiveness.
For example, in a case like this:
%0 = alloca [50025 x i32], align 4
%1 = getelementptr inbounds [50025 x i32]* %0, i64 0, i64 0
store i32 0, i32* %1
%2 = getelementptr inbounds i32* %1, i64 1
store i32 1, i32* %2
%3 = getelementptr inbounds i32* %2, i64 1
store i32 2, i32* %3
%4 = getelementptr inbounds i32* %3, i64 1
store i32 3, i32* %4
%5 = getelementptr inbounds i32* %4, i64 1
store i32 4, i32* %5
%6 = getelementptr inbounds i32* %5, i64 1
store i32 5, i32* %6
...
This piece of code crashes llvm when trying to apply instcombine on
desktop. On embedded devices this could happen with a much lower limit
of recursiveness. Some instructions (getelementptr and bitcasts) make
the function recursively call itself on their uses, which is what makes
the example above consume so much stack (it becomes a recursive
depth-first tree visit with a very big depth).
The patch changes the algorithm to be semantically equivalent, but
iterative instead of recursive and the visiting order to be from a
depth-first visit to a breadth-first visit (visit all the instructions
of the current level before the ones of the next one).
Now if a lot of memory is required a heap allocation is done instead of
the the stack allocation, avoiding the possible crash.
Reviewed By: rnk
Differential Revision: http://reviews.llvm.org/D4355
Patch by Marcello Maggioni! We don't generally commit large stress test
that look for out of memory conditions, so I didn't request that one be
added to the patch.
llvm-svn: 212133
This patch enables transforms for
(x + (~(y | c) + 1) --> x - (y | c) if c is odd
Differential Revision: http://reviews.llvm.org/D4210
llvm-svn: 211881
This patch enables transforms for
(x + (~(y | c) + 1) --> x - (y | c) if c is even
Differential Revision: http://reviews.llvm.org/D4209
llvm-svn: 211765
This patch enables transforms for following patterns.
(x + (~(y & c) + 1) --> x - (y & c)
(x + (~((y >> z) & c) + 1) --> x - ((y>>z) & c)
Differential Revision: http://reviews.llvm.org/D3733
llvm-svn: 211266
* Find factorization opportunities using identity values.
* Find factorization opportunities by treating shl(X, C) as mul (X, shl(C))
* Keep NSW flag while simplifying instruction using factorization.
This fixes PR19263.
Differential Revision: http://reviews.llvm.org/D3799
llvm-svn: 211261
InstCombineMulDivRem has:
// Canonicalize (X+C1)*CI -> X*CI+C1*CI.
InstCombineAddSub has:
// W*X + Y*Z --> W * (X+Z) iff W == Y
These two transforms could fight with each other if C1*CI would not fold
away to something simpler than a ConstantExpr mul.
The InstCombineMulDivRem transform only acted on ConstantInts until
r199602 when it was changed to operate on all Constants in order to
let it fire on ConstantVectors.
To fix this, make this transform more careful by checking to see if we
actually folded away C1*CI.
This fixes PR20079.
llvm-svn: 211258
These will be used for custom lowering and for library
implementations of various math functions, so it's useful
to expose these as builtins.
llvm-svn: 211247
Summary:
As a starting step, we only use one simple heuristic: if the sign bits
of both a and b are zero, we can prove "add a, b" do not unsigned
overflow, and thus convert it to "add nuw a, b".
Updated all affected tests and added two new tests (@zero_sign_bit and
@zero_sign_bit2) in AddOverflow.ll
Test Plan: make check-all
Reviewers: eliben, rafael, meheff, chandlerc
Reviewed By: chandlerc
Subscribers: chandlerc, llvm-commits
Differential Revision: http://reviews.llvm.org/D4144
llvm-svn: 211084
As a follow-up to r210375 which canonicalizes addrspacecast
instructions, this patch canonicalizes addrspacecast constant
expressions.
Given clang uses ConstantExpr::getAddrSpaceCast to emit addrspacecast
cosntant expressions, this patch is also a step towards having the
frontend emit canonicalized addrspacecasts.
Piggyback a minor refactor in InstCombineCasts.cpp
Update three affected tests in addrspacecast-alias.ll,
access-non-generic.ll and constant-fold-gep.ll and added one new test in
constant-fold-address-space-pointer.ll
llvm-svn: 211004
The messages were
"PR19753: Optimize comparisons with "ashr exact" of a constanst."
"Added support to optimize comparisons with "lshr exact" of a constant."
They were not correctly handling signed/unsigned operation differences,
causing pr19958.
llvm-svn: 210393
addrspacecast X addrspace(M)* to Y addrspace(N)*
-->
bitcast X addrspace(M)* to Y addrspace(M)*
addrspacecast Y addrspace(M)* to Y addrspace(N)*
Updat all affected tests and add several new tests in addrspacecast.ll.
This patch is based on http://reviews.llvm.org/D2186 (authored by Matt
Arsenault) with fixes and more tests.
llvm-svn: 210375
Matt Arsenault