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* [JumpThreading] Fix threading with unusual PHI nodes.Eli Friedman2019-07-031-3/+16
| | | | | | | | | | | | | | | | | | | | If the block being cloned contains a PHI node, in general, we need to clone that PHI node, even though it's trivial. If the operand of the PHI is an instruction in the block being cloned, the correct value for the operand doesn't exist until SSAUpdater constructs it. We usually don't hit this issue because we try to avoid threading across loop headers, but it's possible to hit this in some cases involving irreducible CFGs. I added a flag to allow threading across loop headers to make the testcase easier to understand. Thanks to Brian Rzycki for reducing the testcase. Fixes https://bugs.llvm.org/show_bug.cgi?id=42085. Differential Revision: https://reviews.llvm.org/D63913 llvm-svn: 365094
* Simplify std::lower_bound with llvm::{bsearch,lower_bound}. NFCFangrui Song2019-06-211-2/+1
| | | | llvm-svn: 364006
* [JumpThreading] A bug fix for stale loop info after unfold selectHiroshi Yamauchi2019-05-151-1/+2
| | | | | | | | | | | | | | | | | | | | Summary: The return value of a TryToUnfoldSelect call was not checked, which led to an incorrectly preserved loop info and some crash. The original crash was reported on https://reviews.llvm.org/D59514. Reviewers: davidxl, amehsan Reviewed By: davidxl Subscribers: fhahn, brzycki, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D61920 llvm-svn: 360780
* [JumpThreading] Fix incorrect fold conditional after indirectbr/callbrBrian M. Rzycki2019-04-081-5/+1
| | | | | | | | | | | | | | | | | | | | | Fixes bug 40992: https://bugs.llvm.org/show_bug.cgi?id=40992 There is potential for miscompiled code emitted from JumpThreading when analyzing a block with one or more indirectbr or callbr predecessors. The ProcessThreadableEdges() function incorrectly folds conditional branches into an unconditional branch. This patch prevents incorrect branch folding without fully pessimizing other potential threading opportunities through the same basic block. This IR shape was manually fed in via opt and is unclear if clang and the full pass pipeline will ever emit similar code shapes. Thanks to Matthias Liedtke for the bug report and simplified IR example. Differential Revision: https://reviews.llvm.org/D60284 llvm-svn: 357930
* [JumpThreading] Retain debug info when replacing branch instructionsJeremy Morse2019-03-111-2/+5
| | | | | | | | | | | | | | | | | | | | Fixes bug 37966: https://bugs.llvm.org/show_bug.cgi?id=37966 The Jump Threading pass will replace certain conditional branch instructions with unconditional branches when it can prove that only one branch can occur. Prior to this patch, it would not carry the debug info from the old instruction to the new one. This patch fixes the bug described by copying the debug info from the conditional branch instruction to the new unconditional branch instruction, and adds a regression test for the Jump Threading pass that covers this case. Patch by Stephen Tozer! Differential Revision: https://reviews.llvm.org/D58963 llvm-svn: 355822
* [DTU] Refine the interface and logic of applyUpdatesChijun Sima2019-02-221-12/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This patch separates two semantics of `applyUpdates`: 1. User provides an accurate CFG diff and the dominator tree is updated according to the difference of `the number of edge insertions` and `the number of edge deletions` to infer the status of an edge before and after the update. 2. User provides a sequence of hints. Updates mentioned in this sequence might never happened and even duplicated. Logic changes: Previously, removing invalid updates is considered a side-effect of deduplication and is not guaranteed to be reliable. To handle the second semantic, `applyUpdates` does validity checking before deduplication, which can cause updates that have already been applied to be submitted again. Then, different calls to `applyUpdates` might cause unintended consequences, for example, ``` DTU(Lazy) and Edge A->B exists. 1. DTU.applyUpdates({{Delete, A, B}, {Insert, A, B}}) // User expects these 2 updates result in a no-op, but {Insert, A, B} is queued 2. Remove A->B 3. DTU.applyUpdates({{Delete, A, B}}) // DTU cancels this update with {Insert, A, B} mentioned above together (Unintended) ``` But by restricting the precondition that updates of an edge need to be strictly ordered as how CFG changes were made, we can infer the initial status of this edge to resolve this issue. Interface changes: The second semantic of `applyUpdates` is separated to `applyUpdatesPermissive`. These changes enable DTU(Lazy) to use the first semantic if needed, which is quite useful in `transforms/utils`. Reviewers: kuhar, brzycki, dmgreen, grosser Reviewed By: brzycki Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D58170 llvm-svn: 354669
* [DTU] Deprecate insertEdge*/deleteEdge*Chijun Sima2019-02-221-2/+2
| | | | | | | | | | | | | | | | Summary: This patch converts all existing `insertEdge*/deleteEdge*` to `applyUpdates` and marks `insertEdge*/deleteEdge*` as deprecated. Reviewers: kuhar, brzycki Reviewed By: kuhar, brzycki Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D58443 llvm-svn: 354652
* Implementation of asm-goto support in LLVMCraig Topper2019-02-081-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | This patch accompanies the RFC posted here: http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html This patch adds a new CallBr IR instruction to support asm-goto inline assembly like gcc as used by the linux kernel. This instruction is both a call instruction and a terminator instruction with multiple successors. Only inline assembly usage is supported today. This also adds a new INLINEASM_BR opcode to SelectionDAG and MachineIR to represent an INLINEASM block that is also considered a terminator instruction. There will likely be more bug fixes and optimizations to follow this, but we felt it had reached a point where we would like to switch to an incremental development model. Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii Differential Revision: https://reviews.llvm.org/D53765 llvm-svn: 353563
* Move DomTreeUpdater from IR to AnalysisRichard Trieu2019-02-061-1/+1
| | | | | | | | DomTreeUpdater depends on headers from Analysis, but is in IR. This is a layering violation since Analysis depends on IR. Relocate this code from IR to Analysis to fix the layering violation. llvm-svn: 353265
* [opaque pointer types] Pass value type to LoadInst creation.James Y Knight2019-02-011-5/+5
| | | | | | | | | This cleans up all LoadInst creation in LLVM to explicitly pass the value type rather than deriving it from the pointer's element-type. Differential Revision: https://reviews.llvm.org/D57172 llvm-svn: 352911
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* [Jump Threading] Unfold a select insn that feeds a switch via a phi nodeEhsan Amiri2019-01-111-28/+70
| | | | | | | | | | | Currently when a select has a constant value in one branch and the select feeds a conditional branch (via a compare/ phi and compare) we unfold the select statement. This results in threading the conditional branch later on. Similar opportunity exists when a select (with a constant in one branch) feeds a switch (via a phi node). The patch unfolds select under this condition. A testcase is provided. llvm-svn: 350931
* [CSP, Cloning] Update DuplicateInstructionsInSplitBetween to use DomTreeUpdater.Florian Hahn2018-11-131-14/+2
| | | | | | | | | | | | | | | | | | | | | This patch updates DuplicateInstructionsInSplitBetween to update a DTU instead of applying updates to the DT directly. Given that there only are 2 users, also updated them in this patch to avoid churn. I slightly moved the code in CallSiteSplitting around to reduce the places where we have to pass in DTU. If necessary, I could split those changes in a separate patch. This fixes missing DT updates when dealing with musttail calls in CallSiteSplitting, by using DTU->deleteBB. Reviewers: junbuml, kuhar, NutshellySima, indutny, brzycki Reviewed By: NutshellySima llvm-svn: 346769
* [JumpThreading] Fix exponential time algorithm computing known values.Eli Friedman2018-11-091-19/+18
| | | | | | | | | | | | | | | | | | | ComputeValueKnownInPredecessors has a "visited" set to prevent infinite loops, since a value can be visited more than once. However, the implementation didn't prevent the algorithm from taking exponential time. Instead of removing elements from the RecursionSet one at a time, we should keep around the whole set until ComputeValueKnownInPredecessors finishes, then discard it. The testcase is synthetic because I was having trouble effectively reducing the original. But it's basically the same idea. Instead of failing, we could theoretically cache the result instead. But I don't think it would help substantially in practice. Differential Revision: https://reviews.llvm.org/D54239 llvm-svn: 346562
* [TI removal] Remove `TerminatorInst` from BasicBlockUtils.hChandler Carruth2018-10-151-8/+8
| | | | | | | | | This requires updating a number of .cpp files to adapt to the new API. I've just systematically updated all uses of `TerminatorInst` within these files te `Instruction` so thta I won't have to touch them again in the future. llvm-svn: 344498
* Re-enable "[NFC] Unify guards detection"Max Kazantsev2018-08-301-3/+3
| | | | | | | | | | rL340921 has been reverted by rL340923 due to linkage dependency from Transform/Utils to Analysis which is not allowed. In this patch this has been fixed, a new utility function moved to Analysis. Differential Revision: https://reviews.llvm.org/D51152 llvm-svn: 341014
* Revert r340921 "[NFC] Unify guards detection"Hans Wennborg2018-08-291-3/+3
| | | | | | | | | | | | | | | | | | This broke the build, see e.g. http://lab.llvm.org:8011/builders/clang-cmake-armv8-lnt/builds/4626/ http://lab.llvm.org:8011/builders/clang-ppc64be-linux-lnt/builds/18647/ http://lab.llvm.org:8011/builders/clang-cmake-x86_64-avx2-linux/builds/5856/ http://lab.llvm.org:8011/builders/lld-x86_64-freebsd/builds/22800/ > We have multiple places in code where we try to identify whether or not > some instruction is a guard. This patch factors out this logic into a separate > utility function which works uniformly in all places. > > Differential Revision: https://reviews.llvm.org/D51152 > Reviewed By: fedor.sergeev llvm-svn: 340923
* [NFC] Unify guards detectionMax Kazantsev2018-08-291-3/+3
| | | | | | | | | | | We have multiple places in code where we try to identify whether or not some instruction is a guard. This patch factors out this logic into a separate utility function which works uniformly in all places. Differential Revision: https://reviews.llvm.org/D51152 Reviewed By: fedor.sergeev llvm-svn: 340921
* [IR] Replace `isa<TerminatorInst>` with `isTerminator()`.Chandler Carruth2018-08-261-1/+1
| | | | | | | | | | | | This is a bit awkward in a handful of places where we didn't even have an instruction and now we have to see if we can build one. But on the whole, this seems like a win and at worst a reasonable cost for removing `TerminatorInst`. All of this is part of the removal of `TerminatorInst` from the `Instruction` type hierarchy. llvm-svn: 340701
* [IR] Sink `isExceptional` predicate to `Instruction`, rename it toChandler Carruth2018-08-261-1/+1
| | | | | | | | | | | `isExceptionalTermiantor` and implement it for opcodes as well following the common pattern in `Instruction`. Part of removing `TerminatorInst` from the `Instruction` type hierarchy to make it easier to share logic and interfaces between instructions that are both terminators and not terminators. llvm-svn: 340699
* [Local] Make DoesKMove required for combineMetadata.Florian Hahn2018-08-241-2/+2
| | | | | | | | | | | | | | | This patch makes the DoesKMove argument non-optional, to force people to think about it. Most cases where it is false are either code hoisting or code sinking, where we pick one instruction from a set of equal instructions among different code paths. Reviewers: dberlin, nlopes, efriedma, davide Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D47475 llvm-svn: 340606
* [Dominators] Convert existing passes and utils to use the DomTreeUpdater classChijun Sima2018-08-031-37/+41
| | | | | | | | | | | | | | | | | | Summary: This patch is the second in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]]. It converts passes (e.g. adce/jump-threading) and various functions which currently accept DDT in local.cpp and BasicBlockUtils.cpp to use the new DomTreeUpdater class. These converted functions in utils can accept DomTreeUpdater with either UpdateStrategy and can deal with both DT and PDT held by the DomTreeUpdater. Reviewers: brzycki, kuhar, dmgreen, grosser, davide Reviewed By: brzycki Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D48967 llvm-svn: 338814
* Revert r332168: "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading.""Michael Zolotukhin2018-07-051-19/+15
| | | | | | | There were a couple of issues reported (PR38047, PR37929) - I'll reland the patch when I figure out and fix the rootcause. llvm-svn: 336393
* [JumpThreading] Don't try to rewrite a use if it's already valid.Michael Zolotukhin2018-06-261-10/+12
| | | | | | | | | | | | | | | | | | | Summary: When recording uses we need to rewrite after cloning a loop we need to check if the use is not dominated by the original def. The initial assumption was that the cloned basic block will introduce a new path and thus the original def will only dominate the use if they are in the same BB, but as the reproducer from PR37745 shows it's not always the case. This fixes PR37745. Reviewers: haicheng, Ka-Ka Subscribers: hiraditya, llvm-commits Differential Revision: https://reviews.llvm.org/D48111 llvm-svn: 335675
* [NFC] fix trivial typos in commentsHiroshi Inoue2018-06-141-3/+3
| | | | llvm-svn: 334687
* Move Analysis/Utils/Local.h back to TransformsDavid Blaikie2018-06-041-1/+1
| | | | | | | | | | Review feedback from r328165. Split out just the one function from the file that's used by Analysis. (As chandlerc pointed out, the original change only moved the header and not the implementation anyway - which was fine for the one function that was used (since it's a template/inlined in the header) but not in general) llvm-svn: 333954
* [JumpThreading] Fix some strange formatting of code inside LLVM_DEBUG. NFCCraig Topper2018-05-311-5/+5
| | | | | | I don't know if clang-format got confused here or what. llvm-svn: 333675
* Rename DEBUG macro to LLVM_DEBUG.Nicola Zaghen2018-05-141-38/+41
| | | | | | | | | | | | | | | | The DEBUG() macro is very generic so it might clash with other projects. The renaming was done as follows: - git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g' - git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM - Manual change to APInt - Manually chage DOCS as regex doesn't match it. In the transition period the DEBUG() macro is still present and aliased to the LLVM_DEBUG() one. Differential Revision: https://reviews.llvm.org/D43624 llvm-svn: 332240
* Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading."Michael Zolotukhin2018-05-121-26/+30
| | | | | | | | | Stage3/stage4 bootstrap miscompares should be fixed by a non-determinism fix in IDF (r332167). This reverts commit r330446. llvm-svn: 332168
* [STLExtras] Add distance() for ranges, pred_size(), and succ_size()Vedant Kumar2018-05-101-4/+3
| | | | | | | | | | | This commit adds a wrapper for std::distance() which works with ranges. As it would be a common case to write `distance(predecessors(BB))`, this also introduces `pred_size()` and `succ_size()` helpers to make that easier to write. Differential Revision: https://reviews.llvm.org/D46668 llvm-svn: 332057
* Fix the issue that ComputeValueKnownInPredecessors only handles the case whenWei Mi2018-05-011-3/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | phi is on lhs of a comparison op. For the following testcase, L1: %t0 = add i32 %m, 7 %t3 = icmp eq i32* %t2, null br i1 %t3, label %L3, label %L2 L2: %t4 = load i32, i32* %t2, align 4 br label %L3 L3: %t5 = phi i32 [ %t0, %L1 ], [ %t4, %L2 ] %t6 = icmp eq i32 %t0, %t5 br i1 %t6, label %L4, label %L5 We know if we go through the path L1 --> L3, %t6 should always be true. However currently, if the rhs of the eq comparison is phi, JumpThreading fails to evaluate %t6 to true. And we know that Instcombine cannot guarantee always canonicalizing phi to the left hand side of the comparison operation according to the operand priority comparison mechanism in instcombine. The patch handles the case when rhs of the comparison op is a phi. Differential Revision: https://reviews.llvm.org/D46275 llvm-svn: 331266
* Revert r330431.Michael Zolotukhin2018-04-201-30/+26
| | | | | | There are still stage3/stage4 miscompares :( llvm-svn: 330446
* Revert "Revert r330403 and r330413."Michael Zolotukhin2018-04-201-26/+30
| | | | | | | | | | | Reapply the patches with a fix. Thanks Ilya and Hans for the reproducer! This reverts commit r330416. The issue was that removing predecessors invalidated uses that we stored for rewrite. The fix is to finish manipulating with CFG before we select uses for rewrite. llvm-svn: 330431
* Revert r330403 and r330413.Ilya Biryukov2018-04-201-20/+16
| | | | | | | | | | | | | | | | Revert r330413: "[SSAUpdaterBulk] Use SmallVector instead of DenseMap for storing rewrites." Revert r330403 "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time." r330403 commit seems to crash clang during our integrate while doing PGO build with the following stacktrace: #2 llvm::SSAUpdaterBulk::RewriteAllUses(llvm::DominatorTree*, llvm::SmallVectorImpl<llvm::PHINode*>*) #3 llvm::JumpThreadingPass::ThreadEdge(llvm::BasicBlock*, llvm::SmallVectorImpl<llvm::BasicBlock*> const&, llvm::BasicBlock*) #4 llvm::JumpThreadingPass::ProcessThreadableEdges(llvm::Value*, llvm::BasicBlock*, llvm::jumpthreading::ConstantPreference, llvm::Instruction*) #5 llvm::JumpThreadingPass::ProcessBlock(llvm::BasicBlock*) The crash happens while compiling 'lib/Analysis/CallGraph.cpp'. r3340413 is reverted due to conflicting changes. llvm-svn: 330416
* [SSAUpdaterBulk] Use SmallVector instead of DenseMap for storing rewrites.Michael Zolotukhin2018-04-201-3/+1
| | | | llvm-svn: 330413
* Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time.Michael Zolotukhin2018-04-201-16/+22
| | | | | | | | | Hopefully, changing set to vector removes nondeterminism detected by some bots, or the new assert will catch something. This reverts commit r330180. llvm-svn: 330403
* Revert "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." again."Michael Zolotukhin2018-04-171-22/+15
| | | | | | This reverts r330175. There are still stage3/stage4 miscompares. llvm-svn: 330180
* Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." again.Michael Zolotukhin2018-04-171-15/+22
| | | | | | | | | One more, hopefully the last, bug is fixed: when forming UsesToRewrite we should ignore phi operands coming from edges that we want to delete. This reverts r329910. llvm-svn: 330175
* Revert "Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time."Benjamin Kramer2018-04-121-18/+13
| | | | | | This reverts commit r329865. Causes stage2/stage3 miscompare. llvm-svn: 329910
* Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time.Michael Zolotukhin2018-04-111-13/+18
| | | | | | This reapplies commit r329644. llvm-svn: 329865
* Revert "[PR16756] Use SSAUpdaterBulk in JumpThreading." one more time.Michael Zolotukhin2018-04-101-18/+13
| | | | | | This reverts r329661. Bots are still unhappy. llvm-svn: 329666
* Revert "Revert "[PR16756] Use SSAUpdaterBulk in JumpThreading.""Michael Zolotukhin2018-04-101-13/+18
| | | | | | This reapplies commit r329644. llvm-svn: 329661
* Revert "[PR16756] Use SSAUpdaterBulk in JumpThreading."Michael Zolotukhin2018-04-101-18/+13
| | | | | | This reverts commit r329644. llvm-svn: 329650
* [PR16756] Use SSAUpdaterBulk in JumpThreading.Michael Zolotukhin2018-04-091-13/+18
| | | | | | | | | | | | | | | | | Summary: SSAUpdater is a bottleneck in JumpThreading, and this patch improves the situation by using SSAUpdaterBulk instead. Compile time impact: no noticable changes on CTMark, a big improvement on the test from PR16756. Reviewers: dberlin, davide, MatzeB Subscribers: llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D44282 llvm-svn: 329644
* [JumpThreading] Don't select an edge that we know we can't threadHaicheng Wu2018-03-291-1/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In r312664 (D36404), JumpThreading stopped threading edges into loop headers. Unfortunately, I observed a significant performance regression as a result of this change. Upon further investigation, the problematic pattern looked something like this (after many high level optimizations): while (true) { bool cond = ...; if (!cond) { <body> } if (cond) break; } Now, naturally we want jump threading to essentially eliminate the second if check and hook up the edges appropriately. However, the above mentioned change, prevented it from doing this because it would have to thread an edge into the loop header. Upon further investigation, what is happening is that since both branches are threadable, JumpThreading picks one of them at arbitrarily. In my case, because of the way that the IR ended up, it tended to pick the one to the loop header, bailing out immediately after. However, if it had picked the one to the exit block, everything would have worked out fine (because the only remaining branch would then be folded, not thraded which is acceptable). Thus, to fix this problem, we can simply eliminate loop headers from consideration as possible threading targets earlier, to make sure that if there are multiple eligible branches, we can still thread one of the ones that don't target a loop header. Patch by Keno Fischer! Differential Revision: https://reviews.llvm.org/D42260 llvm-svn: 328798
* Fix a couple of layering violations in TransformsDavid Blaikie2018-03-211-1/+1
| | | | | | | | | | | | | Remove #include of Transforms/Scalar.h from Transform/Utils to fix layering. Transforms depends on Transforms/Utils, not the other way around. So remove the header and the "createStripGCRelocatesPass" function declaration (& definition) that is unused and motivated this dependency. Move Transforms/Utils/Local.h into Analysis because it's used by Analysis/MemoryBuiltins.cpp. llvm-svn: 328165
* [JumpThreading] Track unreachable BBs to avoid processingBrian M. Rzycki2018-03-161-47/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | JumpThreading iterates over F until the IR quiesces. Transforming unreachable BBs increases compile time and it is also possible to never stabilize causing JumpThreading to hang. An older attempt at fixing this problem was D3991 where removeUnreachableBlocks(F) was called before JumpThreading began. This has a few drawbacks: * expensive - the routine attempts to fix up the IR to identify additional BBs that can be removed along with unreachable BBs. * aggressive - does not identify and preserve the shape of the IR. At a minimum it does not preserve loop hierarchies. * invasive - altering reachable blocks it may disrupt IR shapes that could have otherwise been JumpThreaded. This patch avoids removeUnreachableBlocks(F) and instead tracks unreachable BBs in a SmallPtrSet using DominatorTree to validate the initial state of all BBs. We then rely on subsequent passes to identify and remove these unreachable blocks from F. Reviewers: dberlin, sebpop, kuhar, dinesh.d Reviewed by: sebpop, kuhar Subscribers: hiraditya, uabelho, llvm-commits Differential Revision: https://reviews.llvm.org/D44177 llvm-svn: 327713
* [JumpThreading] Don't restrict cast-traversal to i1Chad Rosier2018-03-091-3/+1
| | | | | | | | | | | | | | | | | | | In r263618, JumpThreading learned to look trough simple cast instructions, but only if the source of those cast instructions was a phi/cmp i1 (in an effort to limit compile time effects). I think this condition is too restrictive. For switches with limited value range, InstCombine will readily introduce an extra trunc instruction to a smaller integer type (e.g. from i8 to i2), leaving us in the somewhat perverse situation that jump-threading would work before running instcombine, but not after. Since instcombine produces this pattern, I think we need to consider it canonical and support it in JumpThreading. In general, for limiting recursion, I think the existing restriction to phi and cmp nodes should be sufficient to avoid looking through unprofitable chains of instructions. Patch by Keno Fischer! Differential Revision: https://reviews.llvm.org/D42262 llvm-svn: 327150
* [NFC] Factor out a helper function for checking if a block has a potential ↵Philip Reames2018-03-081-3/+1
| | | | | | early implicit exit. llvm-svn: 327065
* [JumpThreading] PR36133 enable/disable DominatorTree for LVI analysisBrian M. Rzycki2018-02-161-0/+37
| | | | | | | | | | | | | | | | | | | | | | Summary: The LazyValueInfo pass caches a copy of the DominatorTree when available. Whenever there are pending DominatorTree updates within JumpThreading's DeferredDominance object we cannot use the cached DT for LVI analysis. This commit adds the new methods enableDT() and disableDT() to LVI. JumpThreading also sets the appropriate usage model before calling LVI analysis methods. Fixes https://bugs.llvm.org/show_bug.cgi?id=36133 Reviewers: sebpop, dberlin, kuhar Reviewed by: sebpop, kuhar Subscribers: uabelho, llvm-commits, aprantl, hiraditya, a.elovikov Differential Revision: https://reviews.llvm.org/D42717 llvm-svn: 325356
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