bcm5719-llvm/llvm/test/Transforms/EarlyCSE, branch meklort-10.0.1

[EarlyCSE] avoid crashing when detecting min/max/abs patterns (PR41083)

2020-03-19T09:02:25+00:00

As discussed in PR41083: https://bugs.llvm.org/show_bug.cgi?id=41083 ...we can assert/crash in EarlyCSE using the current hashing scheme and instructions with flags. ValueTracking's matchSelectPattern() may rely on overflow (nsw, etc) or other flags when detecting patterns such as min/max/abs composed of compare+select. But the value numbering / hashing mechanism used by EarlyCSE intersects those flags to allow more CSE. Several alternatives to solve this are discussed in the bug report. This patch avoids the issue by doing simple matching of min/max/abs patterns that never requires instruction flags. We give up some CSE power because of that, but that is not expected to result in much actual performance difference because InstCombine will canonicalize these patterns when possible. It even has this comment for abs/nabs: /// Canonicalize all these variants to 1 pattern. /// This makes CSE more likely. (And this patch adds PhaseOrdering tests to verify that the expected transforms are still happening in the standard optimization pipelines. I left this code to use ValueTracking's "flavor" enum values, so we don't have to change the callers' code. If we decide to go back to using the ValueTracking call (by changing the hashing algorithm instead), it should be obvious how to replace this chunk. Differential Revision: https://reviews.llvm.org/D74285 (cherry picked from commit b8ebc11f032032c7ca449f020a1fe40346e707c8)

Reapply: [DebugInfo] Correctly handle salvaged casts and split fragments at ISel

2019-12-18T16:26:42+00:00

This reverts commit 1f3dd83cc1f2b8f72b9d59e2b4221b12fb7f9a95, reapplying commit bb1b0bc4e57428ce364d3d6c075ff03cb8973462. The original commit failed on some builds seemingly due to the use of a bracketed constructor with an std::array, i.e. `std::array<> arr({...})`.

Revert "[DebugInfo] Correctly handle salvaged casts and split fragments at ISel"

2019-12-18T11:46:10+00:00

Reverted due to build failure on windows bots. This reverts commit bb1b0bc4e57428ce364d3d6c075ff03cb8973462.

[DebugInfo] Correctly handle salvaged casts and split fragments at ISel

2019-12-18T11:09:18+00:00

Previously, LLVM had no functional way of performing casts inside of a DIExpression(), which made salvaging cast instructions other than Noop casts impossible. This patch enables the salvaging of casts by using the DW_OP_LLVM_convert operator for SExt and Trunc instructions. There is another issue which is exposed by this fix, in which fragment DIExpressions (which are preserved more readily by this patch) for values that must be split across registers in ISel trigger an assertion, as the 'split' fragments extend beyond the bounds of the fragment DIExpression causing an error. This patch also fixes this issue by checking the fragment status of DIExpressions which are to be split, and dropping fragments that are invalid.

[IR] Fix mayReadFromMemory() for writeonly calls

2019-10-21T06:52:08+00:00

Current implementation of Instruction::mayReadFromMemory() returns !doesNotAccessMemory() which is !ReadNone. This does not take into account that the writeonly attribute also indicates that the call does not read from memory. The patch changes the predicate to !doesNotReadMemory() that reflects the intended behavior. Differential Revision: https://reviews.llvm.org/D69086 llvm-svn: 375389

[EarlyCSE] Add support for unary FNeg to EarlyCSE

2019-08-07T14:34:41+00:00

Differential Revision: https://reviews.llvm.org/D65815 llvm-svn: 368171

[NFC][EarlyCSE] Pre-commit unary FNeg tests.

2019-08-06T16:41:30+00:00

llvm-svn: 368056

[EarlyCSE] Fix hashing of self-compares

2019-06-17T19:11:28+00:00

Summary: Update compare normalization in SimpleValue hashing to break ties (when the same value is being compared to itself) by switching to the swapped predicate if it has a lower numerical value. This brings the hashing in line with isEqual, which already recognizes the self-compares with swapped predicates as equal. Fixes PR 42280. Reviewers: spatel, efriedma, nikic, fhahn, uabelho Reviewed By: nikic Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D63349 llvm-svn: 363598

[EarlyCSE] Ensure equal keys have the same hash value

2019-06-13T15:24:11+00:00

Summary: The logic in EarlyCSE that looks through 'not' operations in the predicate recognizes e.g. that `select (not (cmp sgt X, Y)), X, Y` is equivalent to `select (cmp sgt X, Y), Y, X`. Without this change, however, only the latter is recognized as a form of `smin X, Y`, so the two expressions receive different hash codes. This leads to missed optimization opportunities when the quadratic probing for the two hashes doesn't happen to collide, and assertion failures when probing doesn't collide on insertion but does collide on a subsequent table grow operation. This change inverts the order of some of the pattern matching, checking first for the optional `not` and then for the min/max/abs patterns, so that e.g. both expressions above are recognized as a form of `smin X, Y`. It also adds an assertion to isEqual verifying that it implies equal hash codes; this fires when there's a collision during insertion, not just grow, and so will make it easier to notice if these functions fall out of sync again. A new flag --earlycse-debug-hash is added which can be used when changing the hash function; it forces hash collisions so that any pair of values inserted which compare as equal but hash differently will be caught by the isEqual assertion. Reviewers: spatel, nikic Reviewed By: spatel, nikic Subscribers: lebedev.ri, arsenm, craig.topper, efriedma, hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D62644 llvm-svn: 363274

[EarlyCSE] Add tests for negated min/max/abs [NFC]

2019-06-05T21:30:10+00:00

Summary: I'm planning to update the hashing logic to recognize their equivalence in a subsequent change (D62644). Reviewers: spatel Reviewed By: spatel Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D62918 llvm-svn: 362657