Commit Graph

5 Commits

Author SHA1 Message Date
David Green da21170c49 [ConstantFolding] Fix to prevent constant folding having to repeatedly scan operands. NFCI
After the loop unroll threshold was increased in r295538, very
large constant expressions can be created. This prevents them
from having to be recursively scanned, leading to a compile
time blow-up.

Differential Revision: https://reviews.llvm.org/D30689

llvm-svn: 298356
2017-03-21 10:17:39 +00:00
Javed Absar 382f98733a [ConstantFold] Fix defect in constant folding computation for GEP
When the array indexes are all determined by GVN to be constants,
a call is made to constant-folding to optimize/simplify the address
computation.

The constant-folding, however, makes a mistake in that it sometimes reads
back stale Idxs instead of NewIdxs, that it re-computed in previous iteration.
This leads to incorrect addresses coming out of constant-folding to GEP.
A test case is included. The error is only triggered when indexes have particular
patterns that the stale/new index updates interplay matters.

Reviewers: Daniel Berlin
Differential Revision: https://reviews.llvm.org/D30642

llvm-svn: 297317
2017-03-08 23:01:50 +00:00
Michael Kuperstein dd92c78669 [ConstantFolding] Fix vector GEPs harder
For vector GEPs, CastGEPIndices can end up in an infinite recursion, because
we compare the vector type to the scalar pointer type, find them different,
and then try to cast a type to itself.

Differential Revision: https://reviews.llvm.org/D28009

llvm-svn: 290260
2016-12-21 17:34:21 +00:00
Keno Fischer dc09119776 ConstantFolding: Don't crash when encountering vector GEP
ConstantFolding tried to cast one of the scalar indices to a vector
type. Instead, use the vector type only for the first index (which
is the only one allowed to be a vector) and use its scalar type
otherwise.

Fixes PR31250.

Reviewers: majnemer
Differential Revision: https://reviews.llvm.org/D27389

llvm-svn: 289073
2016-12-08 17:22:35 +00:00
Peter Collingbourne d93620bf4d IR: Introduce inrange attribute on getelementptr indices.
If the inrange keyword is present before any index, loading from or
storing to any pointer derived from the getelementptr has undefined
behavior if the load or store would access memory outside of the bounds of
the element selected by the index marked as inrange.

This can be used, e.g. for alias analysis or to split globals at element
boundaries where beneficial.

As previously proposed on llvm-dev:
http://lists.llvm.org/pipermail/llvm-dev/2016-July/102472.html

Differential Revision: https://reviews.llvm.org/D22793

llvm-svn: 286514
2016-11-10 22:34:55 +00:00