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* [SimplifyCFG] Skip sinking common lifetime markers of `alloca`.Michael Liao2019-08-291-0/+27
| | | | | | | | | | | | | | | Summary: - Similar to the workaround in fix of PR30188, skip sinking common lifetime markers of `alloca`. They are mostly left there after inlining functions in branches. Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66950 llvm-svn: 370376
* Re-commit r357452 (take 3): "SimplifyCFG SinkCommonCodeFromPredecessors: ↵Hans Wennborg2019-06-171-0/+44
| | | | | | | | | | | Also sink function calls without used results (PR41259)" Third time's the charm. This was reverted in r363220 due to being suspected of an internal benchmark regression and a test failure, none of which turned out to be caused by this. llvm-svn: 363529
* Revert r361811: 'Re-commit r357452 (take 2): "SimplifyCFG ↵David L. Jones2019-06-131-44/+0
| | | | | | | | | | | | | | | | SinkCommonCodeFromPredecessors ...' We have observed some failures with internal builds with this revision. - Performance regressions: - llvm's SingleSource/Misc evalloop shows performance regressions (although these may be red herrings). - Benchmarks for Abseil's SwissTable. - Correctness: - Failures for particular libicu tests when building the Google AppEngine SDK (for PHP). hwennborg has already been notified, and is aware of reproducer failures. llvm-svn: 363220
* Re-commit r357452 (take 2): "SimplifyCFG SinkCommonCodeFromPredecessors: ↵Hans Wennborg2019-05-281-0/+44
| | | | | | | | | | | | | | | | | | | | Also sink function calls without used results (PR41259)" This was reverted in r360086 as it was supected of causing mysterious test failures internally. However, it was never concluded that this patch was the root cause. > The code was previously checking that candidates for sinking had exactly > one use or were a store instruction (which can't have uses). This meant > we could sink call instructions only if they had a use. > > That limitation seemed a bit arbitrary, so this patch changes it to > "instruction has zero or one use" which seems more natural and removes > the need to special-case stores. > > Differential revision: https://reviews.llvm.org/D59936 llvm-svn: 361811
* Revert "Re-commit r357452: SimplifyCFG SinkCommonCodeFromPredecessors: Also ↵Jordan Rupprecht2019-05-061-44/+0
| | | | | | | | | | sink function calls without used results (PR41259)" This reverts r357452 (git commit 21eb771dcb5c11d7500fa6ad551c97a921997f05). This was causing strange optimization-related test failures on an internal test. Will followup with more details offline. llvm-svn: 360086
* Revert "Temporarily Revert "Add basic loop fusion pass.""Eric Christopher2019-04-171-0/+892
| | | | | | | | The reversion apparently deleted the test/Transforms directory. Will be re-reverting again. llvm-svn: 358552
* Temporarily Revert "Add basic loop fusion pass."Eric Christopher2019-04-171-892/+0
| | | | | | | | As it's causing some bot failures (and per request from kbarton). This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda. llvm-svn: 358546
* Re-commit r357452: SimplifyCFG SinkCommonCodeFromPredecessors: Also sink ↵Hans Wennborg2019-04-161-0/+44
| | | | | | | | | | | | | | | | | | | function calls without used results (PR41259) The original commit caused false positives from AddressSanitizer's use-after-scope checks, which have now been fixed in r358478. > The code was previously checking that candidates for sinking had exactly > one use or were a store instruction (which can't have uses). This meant > we could sink call instructions only if they had a use. > > That limitation seemed a bit arbitrary, so this patch changes it to > "instruction has zero or one use" which seems more natural and removes > the need to special-case stores. > > Differential revision: https://reviews.llvm.org/D59936 llvm-svn: 358483
* [NewPM] Add Option handling for SimplifyCFGSerguei Katkov2019-04-151-0/+1
| | | | | | | | | | | This patch enables passing options to SimplifyCFGPass via the passes pipeline. Reviewers: chandlerc, fedor.sergeev, leonardchan, philip.pfaffe Reviewed By: fedor.sergeev Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D60675 llvm-svn: 358379
* Revert r357452 - 'SimplifyCFG SinkCommonCodeFromPredecessors: Also sink ↵David L. Jones2019-04-041-44/+0
| | | | | | | | | | function calls without used results (PR41259)' This revision causes tests to fail under ASAN. Since the cause of the failures is not clear (could be ASAN, could be a Clang bug, could be a bug in this revision), the safest course of action seems to be to revert while investigating. llvm-svn: 357667
* SimplifyCFG SinkCommonCodeFromPredecessors: Also sink function calls without ↵Hans Wennborg2019-04-021-0/+44
| | | | | | | | | | | | | | | | used results (PR41259) The code was previously checking that candidates for sinking had exactly one use or were a store instruction (which can't have uses). This meant we could sink call instructions only if they had a use. That limitation seemed a bit arbitrary, so this patch changes it to "instruction has zero or one use" which seems more natural and removes the need to special-case stores. Differential revision: https://reviews.llvm.org/D59936 llvm-svn: 357452
* [SimplifyCFG] don't sink common insts too soon (PR34603)Sanjay Patel2017-12-141-1/+1
| | | | | | | | | | | | This should solve: https://bugs.llvm.org/show_bug.cgi?id=34603 ...by preventing SimplifyCFG from altering redundant instructions before early-cse has a chance to run. It changes the default (canonical-forming) behavior of SimplifyCFG, so we're only doing the sinking transform later in the optimization pipeline. Differential Revision: https://reviews.llvm.org/D38566 llvm-svn: 320749
* Fix some misc. -enable-var-scope violationsMatt Arsenault2017-11-131-3/+3
| | | | llvm-svn: 318006
* Remove the obsolete offset parameter from @llvm.dbg.valueAdrian Prantl2017-07-281-2/+2
| | | | | | | | | | | | There is no situation where this rarely-used argument cannot be substituted with a DIExpression and removing it allows us to simplify the DWARF backend. Note that this patch does not yet remove any of the newly dead code. rdar://problem/33580047 Differential Revision: https://reviews.llvm.org/D35951 llvm-svn: 309426
* Modify constraints in `llvm::canReplaceOperandWithVariable`Leo Li2017-07-061-0/+24
| | | | | | | | | | | | | | | | | Summary: `Instruction::Switch`: only first operand can be set to a non-constant value. `Instruction::InsertValue` both the first and the second operand can be set to a non-constant value. `Instruction::Alloca` return true for non-static allocation. Reviewers: efriedma Reviewed By: efriedma Subscribers: srhines, pirama, llvm-commits Differential Revision: https://reviews.llvm.org/D34905 llvm-svn: 307294
* [SimplifyCFG] Do not sink and merge inline-asm instructions.Akira Hatanaka2017-01-251-0/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Conservatively disable sinking and merging inline-asm instructions as doing so can potentially create arguments that cannot satisfy the inline-asm constraints. For example, SimplifyCFG used to do the following transformation: (before) if.then: %0 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 8) br label %if.end if.else: %1 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 6) br label %if.end (after) %.sink = select i1 %tobool, i32 6, i32 8 %0 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 %.sink) This would result in a crash in the backend since only immediate integer operands are permitted for constraint "n". rdar://problem/30110806 Differential Revision: https://reviews.llvm.org/D29111 llvm-svn: 293025
* Ignore debug info when making optimization decisions in SimplifyCFG.Dehao Chen2016-10-171-4/+17
| | | | | | | | | | | | Summary: Debug info should *not* affect code generation. This patch properly handles debug info to make sure the generated code are the same with or without debug info. Reviewers: davidxl, mzolotukhin, jmolloy Subscribers: aprantl, llvm-commits Differential Revision: https://reviews.llvm.org/D25286 llvm-svn: 284415
* [SimplifyCFG] Don't create PHI nodes for constant bundle operandsSanjoy Das2016-10-121-0/+26
| | | | | | | | | | | | | | | | | | | | Summary: Constant bundle operands may need to retain their constant-ness for correctness. I'll admit that this is slightly odd, but it looks like SimplifyCFG already does this for things like @llvm.frameaddress and @llvm.stackmap, so I suppose adding one more case is not a big deal. It is possible to add a mechanism to denote bundle operands that need to remain constants, but that's probably too complicated for the time being. Reviewers: jmolloy Subscribers: mcrosier, llvm-commits Differential Revision: https://reviews.llvm.org/D25502 llvm-svn: 284028
* [SimplifyCFG] Update (AND) IR flags when CSE'ing instructionsJames Molloy2016-09-191-0/+56
| | | | | | | | We were updating metadata but not IR flags. Because we pick an arbitrary instruction to be the CSE candidate, it comes down to luck (50% or less chance) if this results in broken codegen or not, which is why PR30373 which is actually not the fault of the commit it was bisected down to. Fixes PR30373. llvm-svn: 281889
* [SimplifyCFG] Be even more conservative in SinkThenElseCodeToEndJames Molloy2016-09-111-12/+23
| | | | | | | | This should *actually* fix PR30244. This cranks up the workaround for PR30188 so that we never sink loads or stores of allocas. The idea is that these should be removed by SROA/Mem2Reg, and any movement of them may well confuse SROA or just cause unwanted code churn. It's not ideal that the midend should be crippled like this, but that unwanted churn can really cause significant regressions in important workloads (tsan). llvm-svn: 281162
* [SimplifyCFG] Harden up the profitability heuristic for block splitting ↵James Molloy2016-09-111-3/+52
| | | | | | | | | | | | during sinking Exposed by PR30244, we will split a block currently if we think we can sink at least one instruction. However this isn't right - the reason we split predecessors is so that we can sink instructions that otherwise couldn't be sunk because it isn't safe to do so - stores, for example. So, change the heuristic to only split if it thinks it can sink at least one non-speculatable instruction. Should fix PR30244. llvm-svn: 281160
* [SimplifyCFG] Update workaround for PR30188 to also include loadsJames Molloy2016-09-071-0/+29
| | | | | | | | I should have realised this the first time around, but if we're avoiding sinking stores where the operands come from allocas so they don't create selects, we also have to do the same for loads because SROA will be just as defective looking at loads of selected addresses as stores. Fixes PR30188 (again). llvm-svn: 280792
* [SimplifyCFG] Check PHI uses more accuratelyJames Molloy2016-09-071-0/+25
| | | | | | | | PR30292 showed a case where our PHI checking wasn't correct. We were checking that all values were used by the same PHI before deciding to sink, but we weren't checking that the incoming values for that PHI were what we expected. As a result, we had to bail out after block splitting which caused us to never reach a steady state in SimplifyCFG. Fixes PR30292. llvm-svn: 280790
* [SimplifyCFG] Add a workaround to fix PR30188James Molloy2016-09-021-0/+23
| | | | | | | | We're sinking stores, which is a good thing, but in the process creating selects for the store address operand, which SROA/Mem2Reg can't look through, which caused serious regressions. The real fix is in SROA, which I'll be looking into. llvm-svn: 280470
* [SimplifyCFG] Handle tail-sinking of more than 2 incoming branchesJames Molloy2016-09-011-0/+111
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This was a real restriction in the original version of SinkIfThenCodeToEnd. Now it's been rewritten, the restriction can be lifted. As part of this, we handle a very common and useful case where one of the incoming branches is actually conditional. Consider: if (a) x(1); else if (b) x(2); This produces the following CFG: [if] / \ [x(1)] [if] | | \ | | \ | [x(2)] | \ | / [ end ] [end] has two unconditional predecessor arcs and one conditional. The conditional refers to the implicit empty 'else' arc. This same pattern can also be caused by an empty default block in a switch. We can't sink the call to x() down to end because no call to x() happens on the third incoming arc (assume that x() has sideeffects for the sake of argument; if something is safe to speculate we could indeed sink nevertheless but this cannot happen in the general case and causes many extra selects). We are now able to detect this case and split off the unconditional arcs to a common successor: [if] / \ [x(1)] [if] | | \ | | \ | [x(2)] | \ / | [sink.split] | \ / [ end ] Now we can sink the call to x() into %sink.split. This can cause significant code simplification in many testcases. llvm-svn: 280364
* [SimplifyCFG] Change the algorithm in SinkThenElseCodeToEndJames Molloy2016-09-011-0/+84
| | | | | | | | | | | | | | | | | | | | | | | | | r279460 rewrote this function to be able to handle more than two incoming edges and took pains to ensure this didn't regress anything. This time we change the logic for determining if an instruction should be sunk. Previously we used a single pass greedy algorithm - sink instructions until one requires more than one PHI node or we run out of instructions to sink. This had the problem that sinking instructions that had non-identical but trivially the same operands needed extra logic so we sunk them aggressively. For example: %a = load i32* %b %d = load i32* %b %c = gep i32* %a, i32 0 %e = gep i32* %d, i32 1 Sinking %c and %e would naively require two PHI merges as %a != %d. But the loads are obviously equivalent (and maybe can't be hoisted because there is no common predecessor). This is why we implemented the fairly complex function areValuesTriviallySame(), to look through trivial differences like this. However it's just not clever enough. Instead, throw areValuesTriviallySame away, use pointer equality to check equivalence of operands and switch to a two-stage algorithm. In the "scan" stage, we look at every sinkable instruction in isolation from end of block to front. If it's sinkable, we keep track of all operands that required PHI merging. In the "sink" stage, we iteratively sink the last non-terminator in the source blocks. But when calculating how many PHIs are actually required to be inserted (to work out if we should stop or not) we remove any values that have already been sunk from the set of PHI-merges required, which allows us to be more aggressive. This turns an algorithm with potentially recursive lookahead (looking through GEPs, casts, loads and any other instruction potentially not CSE'd) to two linear scans. llvm-svn: 280351
* Revert "[SimplifyCFG] Change the algorithm in SinkThenElseCodeToEnd"James Molloy2016-08-311-60/+0
| | | | | | This reverts commit r280216 - it caused buildbot failures. llvm-svn: 280234
* Revert "[SimplifyCFG] Handle tail-sinking of more than 2 incoming branches"James Molloy2016-08-311-110/+0
| | | | | | This reverts commit r280217. r280216 caused buildbot failures - backing out the entire chain. llvm-svn: 280233
* Revert "[SimplifyCFG] Add a workaround to fix PR30188"James Molloy2016-08-311-23/+0
| | | | | | This reverts commit r280219. r280216 caused buildbot failures - backing out the entire chain. llvm-svn: 280232
* Revert "[SimplifyCFG] Fix bootstrap failure after r280220"James Molloy2016-08-311-23/+0
| | | | | | This reverts commit r280228. r280216 caused buildbot failures - backing out the entire sequence. llvm-svn: 280231
* [SimplifyCFG] Fix bootstrap failure after r280220James Molloy2016-08-311-0/+23
| | | | | | We check that a sinking candidate is used by only one PHI node during our legality checks. However for instructions that are used by other sinking candidates our heuristic is less conservative. This can result in a candidate actually being illegal when we come to sink it because of how we sunk a predecessor. Do the used-by-only-one-PHI checks again during sinking to ensure we don't crash. llvm-svn: 280228
* [SimplifyCFG] Add a workaround to fix PR30188James Molloy2016-08-311-0/+23
| | | | | | | | We're sinking stores, which is a good thing, but in the process creating selects for the store address operand, which SROA/Mem2Reg can't look through, which caused serious regressions. The real fix is in SROA, which I'll be looking into. llvm-svn: 280219
* [SimplifyCFG] Handle tail-sinking of more than 2 incoming branchesJames Molloy2016-08-311-0/+110
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This was a real restriction in the original version of SinkIfThenCodeToEnd. Now it's been rewritten, the restriction can be lifted. As part of this, we handle a very common and useful case where one of the incoming branches is actually conditional. Consider: if (a) x(1); else if (b) x(2); This produces the following CFG: [if] / \ [x(1)] [if] | | \ | | \ | [x(2)] | \ | / [ end ] [end] has two unconditional predecessor arcs and one conditional. The conditional refers to the implicit empty 'else' arc. This same pattern can also be caused by an empty default block in a switch. We can't sink the call to x() down to end because no call to x() happens on the third incoming arc (assume that x() has sideeffects for the sake of argument; if something is safe to speculate we could indeed sink nevertheless but this cannot happen in the general case and causes many extra selects). We are now able to detect this case and split off the unconditional arcs to a common successor: [if] / \ [x(1)] [if] | | \ | | \ | [x(2)] | \ / | [sink.split] | \ / [ end ] Now we can sink the call to x() into %sink.split. This can cause significant code simplification in many testcases. llvm-svn: 280217
* [SimplifyCFG] Change the algorithm in SinkThenElseCodeToEndJames Molloy2016-08-311-0/+60
| | | | | | | | | | | | | | | | | | | | | | | | | r279460 rewrote this function to be able to handle more than two incoming edges and took pains to ensure this didn't regress anything. This time we change the logic for determining if an instruction should be sunk. Previously we used a single pass greedy algorithm - sink instructions until one requires more than one PHI node or we run out of instructions to sink. This had the problem that sinking instructions that had non-identical but trivially the same operands needed extra logic so we sunk them aggressively. For example: %a = load i32* %b %d = load i32* %b %c = gep i32* %a, i32 0 %e = gep i32* %d, i32 1 Sinking %c and %e would naively require two PHI merges as %a != %d. But the loads are obviously equivalent (and maybe can't be hoisted because there is no common predecessor). This is why we implemented the fairly complex function areValuesTriviallySame(), to look through trivial differences like this. However it's just not clever enough. Instead, throw areValuesTriviallySame away, use pointer equality to check equivalence of operands and switch to a two-stage algorithm. In the "scan" stage, we look at every sinkable instruction in isolation from end of block to front. If it's sinkable, we keep track of all operands that required PHI merging. In the "sink" stage, we iteratively sink the last non-terminator in the source blocks. But when calculating how many PHIs are actually required to be inserted (to work out if we should stop or not) we remove any values that have already been sunk from the set of PHI-merges required, which allows us to be more aggressive. This turns an algorithm with potentially recursive lookahead (looking through GEPs, casts, loads and any other instruction potentially not CSE'd) to two linear scans. llvm-svn: 280216
* [SimplifyCFG] Tail-merge calls with sideeffectsJames Molloy2016-08-311-1/+24
| | | | | | | | | | | | | This was deliberately disabled during my rewrite of SinkIfThenToEnd to keep behaviour at least vaguely consistent with the previous version and keep it as close to NFC as I could. There's no real reason not to merge sideeffect calls though, so let's do it! Small fixup along the way to ensure we don't create indirect calls. Should fix PR28964. llvm-svn: 280215
* [SimplifyCFG] Properly CSE metadata in SinkThenElseCodeToEndJames Molloy2016-08-301-0/+37
| | | | | | This was missing, meaning the metadata in sunk instructions was potentially bogus and could cause miscompiles. llvm-svn: 280072
* [SimplifyCFG] Rewrite SinkThenElseCodeToEndJames Molloy2016-08-221-0/+229
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [Recommitting now an unrelated assertion in SROA is sorted out] The new version has several advantages: 1) IMSHO it's more readable and neater 2) It handles loads and stores properly 3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch. With this change we can now finally sink load-modify-store idioms such as: if (a) return *b += 3; else return *b += 4; => %z = load i32, i32* %y %.sink = select i1 %a, i32 5, i32 7 %b = add i32 %z, %.sink store i32 %b, i32* %y ret i32 %b When this works for switches it'll be even more powerful. Round 4. This time we should handle all instructions correctly, and not replace any operands that need to be constant with variables. This was really hard to determine safely, so the helper function should be put into the Instruction API. I'll do that as a followup. llvm-svn: 279460
* Revert "[SimplifyCFG] Rewrite SinkThenElseCodeToEnd"James Molloy2016-08-221-229/+0
| | | | | | This reverts commit r279443. It caused buildbot failures. llvm-svn: 279447
* [SimplifyCFG] Rewrite SinkThenElseCodeToEndJames Molloy2016-08-221-0/+229
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new version has several advantages: 1) IMSHO it's more readable and neater 2) It handles loads and stores properly 3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch. With this change we can now finally sink load-modify-store idioms such as: if (a) return *b += 3; else return *b += 4; => %z = load i32, i32* %y %.sink = select i1 %a, i32 5, i32 7 %b = add i32 %z, %.sink store i32 %b, i32* %y ret i32 %b When this works for switches it'll be even more powerful. Round 4. This time we should handle all instructions correctly, and not replace any operands that need to be constant with variables. This was really hard to determine safely, so the helper function should be put into the Instruction API. I'll do that as a followup. llvm-svn: 279443
* Revert "[SimplifyCFG] Rewrite SinkThenElseCodeToEnd"Reid Kleckner2016-08-191-201/+0
| | | | | | | This reverts commit r279229. It breaks intrinsic function calls in diamonds. llvm-svn: 279313
* [SimplifyCFG] Rewrite SinkThenElseCodeToEndJames Molloy2016-08-191-0/+201
| | | | | | | | | | | | | | | | | | | | | | | | | | The new version has several advantages: 1) IMSHO it's more readable and neater 2) It handles loads and stores properly 3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch. With this change we can now finally sink load-modify-store idioms such as: if (a) return *b += 3; else return *b += 4; => %z = load i32, i32* %y %.sink = select i1 %a, i32 5, i32 7 %b = add i32 %z, %.sink store i32 %b, i32* %y ret i32 %b When this works for switches it'll be even more powerful. llvm-svn: 279229
* Revert "[SimplifyCFG] Rewrite SinkThenElseCodeToEnd"Reid Kleckner2016-08-151-177/+0
| | | | | | | | | This reverts commit r278660. It causes downstream assertion failure in InstCombine on shuffle instructions. Comes up in __mm_swizzle_epi32. llvm-svn: 278672
* [SimplifyCFG] Rewrite SinkThenElseCodeToEndJames Molloy2016-08-151-0/+177
| | | | | | | | | | | | | | | | | | | | | | | | | | The new version has several advantages: 1) IMSHO it's more readable and neater 2) It handles loads and stores properly 3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch. With this change we can now finally sink load-modify-store idioms such as: if (a) return *b += 3; else return *b += 4; => %z = load i32, i32* %y %.sink = select i1 %a, i32 5, i32 7 %b = add i32 %z, %.sink store i32 %b, i32* %y ret i32 %b When this works for switches it'll be even more powerful. llvm-svn: 278660
* [SimplifyCFG] Revise common code sinkingMichael Liao2014-12-231-2/+32
| | | | | | | | | | - Fix the case where more than 1 common instructions derived from the same operand cannot be sunk. When a pair of value has more than 1 derived values in both branches, only 1 derived value could be sunk. - Replace BB1 -> (BB2, PN) map with joint value map, i.e. map of (BB1, BB2) -> PN, which is more accurate to track common ops. llvm-svn: 224757
* SimplifyCFG: sink common codes from IF, ELSE blocks down to END block.Manman Ren2012-09-201-0/+53
We already have HoistThenElseCodeToIf, this patch implements SinkThenElseCodeToEnd. When END block has only two predecessors and each predecessor terminates with unconditional branches, we compare instructions in IF and ELSE blocks backwards and check whether we can sink the common instructions down. rdar://12191395 llvm-svn: 164325
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