- Nov 17, 2013
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Hal Finkel authored
This adds a boolean member variable to the PassManagerBuilder to control loop rerolling (just like we have for unrolling and the various vectorization options). This is necessary for control by the frontend. Loop rerolling remains disabled by default at all optimization levels. llvm-svn: 194966
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Hal Finkel authored
Generally speaking, control flow paths with error reporting calls are cold. So far, error reporting calls are calls to perror and calls to fprintf, fwrite, etc. with stderr as the stream. This can be extended in the future. The primary motivation is to improve block placement (the cold attribute affects the static branch prediction heuristics). llvm-svn: 194943
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Hal Finkel authored
llvm-svn: 194941
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Hal Finkel authored
This adds a loop rerolling pass: the opposite of (partial) loop unrolling. The transformation aims to take loops like this: for (int i = 0; i < 3200; i += 5) { a[i] += alpha * b[i]; a[i + 1] += alpha * b[i + 1]; a[i + 2] += alpha * b[i + 2]; a[i + 3] += alpha * b[i + 3]; a[i + 4] += alpha * b[i + 4]; } and turn them into this: for (int i = 0; i < 3200; ++i) { a[i] += alpha * b[i]; } and loops like this: for (int i = 0; i < 500; ++i) { x[3*i] = foo(0); x[3*i+1] = foo(0); x[3*i+2] = foo(0); } and turn them into this: for (int i = 0; i < 1500; ++i) { x[i] = foo(0); } There are two motivations for this transformation: 1. Code-size reduction (especially relevant, obviously, when compiling for code size). 2. Providing greater choice to the loop vectorizer (and generic unroller) to choose the unrolling factor (and a better ability to vectorize). The loop vectorizer can take vector lengths and register pressure into account when choosing an unrolling factor, for example, and a pre-unrolled loop limits that choice. This is especially problematic if the manual unrolling was optimized for a machine different from the current target. The current implementation is limited to single basic-block loops only. The rerolling recognition should work regardless of how the loop iterations are intermixed within the loop body (subject to dependency and side-effect constraints), but the significant restriction is that the order of the instructions in each iteration must be identical. This seems sufficient to capture all current use cases. This pass is not currently enabled by default at any optimization level. llvm-svn: 194939
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- Nov 16, 2013
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Hal Finkel authored
InstCombine, in visitFPTrunc, applies the following optimization to sqrt calls: (fptrunc (sqrt (fpext x))) -> (sqrtf x) but does not apply the same optimization to llvm.sqrt. This is a problem because, to enable vectorization, Clang generates llvm.sqrt instead of sqrt in fast-math mode, and because this optimization is being applied to sqrt and not applied to llvm.sqrt, sometimes the fast-math code is slower. This change makes InstCombine apply this optimization to llvm.sqrt as well. This fixes the specific problem in PR17758, although the same underlying issue (optimizations applied to libcalls are not applied to intrinsics) exists for other optimizations in SimplifyLibCalls. llvm-svn: 194935
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Benjamin Kramer authored
This is common in bitfield code. llvm-svn: 194925
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Arnold Schwaighofer authored
When we vectorize a scalar access with no alignment specified, we have to set the target's abi alignment of the scalar access on the vectorized access. Using the same alignment of zero would be wrong because most targets will have a bigger abi alignment for vector types. This probably fixes PR17878. llvm-svn: 194876
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- Nov 15, 2013
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Manman Ren authored
We used to use std::map<IndicesVector, LoadInst*> for OriginalLoads, and when we try to promote two arguments, they will both write to OriginalLoads causing created loads for the two arguments to have the same original load. And the same tbaa tag and alignment will be put to the created loads for the two arguments. The fix is to use std::map<std::pair<Argument*, IndicesVector>, LoadInst*> for OriginalLoads, so each Argument will write to different parts of the map. PR17906 llvm-svn: 194846
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Kostya Serebryany authored
llvm-svn: 194800
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Bob Wilson authored
I was able to successfully run a bootstrapped LTO build of clang with r194701, so this change does not seem to be the cause of our failing buildbots. llvm-svn: 194789
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Matt Arsenault authored
llvm-svn: 194786
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Bob Wilson authored
This reverts commit 194701. Apple's bootstrapped LTO builds have been failing, and this change (along with compiler-rt 194702-194704) is the only thing on the blamelist. I will either reappy these changes or help debug the problem, depending on whether this fixes the buildbots. llvm-svn: 194780
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- Nov 14, 2013
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Kostya Serebryany authored
llvm-svn: 194701
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Evgeniy Stepanov authored
Indirect call wrapping helps MSanDR (dynamic instrumentation companion tool for MSan) to catch all cases where execution leaves a compiler-instrumented module by allowing the tool to rewrite targets of indirect calls. This change is an optimization that skips wrapping for calls when target is inside the current module. This relies on the linker providing symbols at the begin and end of the module code (or code + data, does not really matter). Gold linker provides such symbols by default. GNU (BFD) linker needs a link flag: -Wl,--defsym=__executable_start=0. More info: https://code.google.com/p/memory-sanitizer/wiki/MSanDR#Native_exec llvm-svn: 194697
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- Nov 13, 2013
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Jakub Staszak authored
llvm-svn: 194601
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Alexey Samsonov authored
llvm-svn: 194568
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Diego Novillo authored
This adds a new scalar pass that reads a file with samples generated by 'perf' during runtime. The samples read from the profile are incorporated and emmited as IR metadata reflecting that profile. The profile file is assumed to have been generated by an external profile source. The profile information is converted into IR metadata, which is later used by the analysis routines to estimate block frequencies, edge weights and other related data. External profile information files have no fixed format, each profiler is free to define its own. This includes both the on-disk representation of the profile and the kind of profile information stored in the file. A common kind of profile is based on sampling (e.g., perf), which essentially counts how many times each line of the program has been executed during the run. The SampleProfileLoader pass is organized as a scalar transformation. On startup, it reads the file given in -sample-profile-file to determine what kind of profile it contains. This file is assumed to contain profile information for the whole application. The profile data in the file is read and incorporated into the internal state of the corresponding profiler. To facilitate testing, I've organized the profilers to support two file formats: text and native. The native format is whatever on-disk representation the profiler wants to support, I think this will mostly be bitcode files, but it could be anything the profiler wants to support. To do this, every profiler must implement the SampleProfile::loadNative() function. The text format is mostly meant for debugging. Records are separated by newlines, but each profiler is free to interpret records as it sees fit. Profilers must implement the SampleProfile::loadText() function. Finally, the pass will call SampleProfile::emitAnnotations() for each function in the current translation unit. This function needs to translate the loaded profile into IR metadata, which the analyzer will later be able to use. This patch implements the first steps towards the above design. I've implemented a sample-based flat profiler. The format of the profile is fairly simplistic. Each sampled function contains a list of relative line locations (from the start of the function) together with a count representing how many samples were collected at that line during execution. I generate this profile using perf and a separate converter tool. Currently, I have only implemented a text format for these profiles. I am interested in initial feedback to the whole approach before I send the other parts of the implementation for review. This patch implements: - The SampleProfileLoader pass. - The base ExternalProfile class with the core interface. - A SampleProfile sub-class using the above interface. The profiler generates branch weight metadata on every branch instructions that matches the profiles. - A text loader class to assist the implementation of SampleProfile::loadText(). - Basic unit tests for the pass. Additionally, the patch uses profile information to compute branch weights based on instruction samples. This patch converts instruction samples into branch weights. It does a fairly simplistic conversion: Given a multi-way branch instruction, it calculates the weight of each branch based on the maximum sample count gathered from each target basic block. Note that this assignment of branch weights is somewhat lossy and can be misleading. If a basic block has more than one incoming branch, all the incoming branches will get the same weight. In reality, it may be that only one of them is the most heavily taken branch. I will adjust this assignment in subsequent patches. llvm-svn: 194566
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Nadav Rotem authored
llvm-svn: 194537
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- Nov 12, 2013
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Nadav Rotem authored
Fold (iszero(A&K1) | iszero(A&K2)) -> (A&(K1|K2)) != (K1|K2) if we know that K1 and K2 are 'one-hot' (only one bit is on). llvm-svn: 194525
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Nadav Rotem authored
FoldBranchToCommonDest merges branches into a single branch with or/and of the condition. It has a heuristics for estimating when some of the dependencies are processed by out-of-order processors. This patch adds another rule to the heuristics that says that if the "BonusInstruction" that we speculatively execute is used by the condition of the second branch then it is okay to hoist it. This change exposes more opportunities for other passes to transform the code. It does not matter that much that we if-convert the code because the selectiondag builder splits or/and branches into multiple branches when profitable. llvm-svn: 194524
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Rafael Espindola authored
Constant merge can merge a constant with implicit alignment with one that has explicit alignment. Before this change it was assuming that the explicit alignment was higher than the implicit one, causing the result to be under aligned in some cases. Fixes pr17815. Patch by Chris Smowton! llvm-svn: 194506
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Benjamin Kramer authored
Both simpler and more powerful than the hand-rolled folding logic. llvm-svn: 194475
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Shuxin Yang authored
llvm-svn: 194457
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Yuchen Wu authored
Also updated test files that were generated from this change. llvm-svn: 194453
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- Nov 11, 2013
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Shuxin Yang authored
The symptom is that an assertion is triggered. The assertion was added by me to detect the situation when value is propagated from dead blocks. (We can certainly get rid of assertion; it is safe to do so, because propagating value from dead block to alive join node is certainly ok.) The root cause of this bug is : edge-splitting is conducted on the fly, the edge being split could be a dead edge, therefore the block that split the critial edge needs to be flagged "dead" as well. There are 3 ways to fix this bug: 1) Get rid of the assertion as I mentioned eariler 2) When an dead edge is split, flag the inserted block "dead". 3) proactively split the critical edges connecting dead and live blocks when new dead blocks are revealed. This fix go for 3) with additional 2 LOC. Testing case was added by Rafael the other day. llvm-svn: 194424
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Renato Golin authored
No functional change, just better reporting. llvm-svn: 194388
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Evgeniy Stepanov authored
llvm-svn: 194374
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- Nov 10, 2013
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Bill Wendling authored
Revert "Resurrect r191017 " GVN proceeds in the presence of dead code" plus a fix to PR17307 & 17308." This causes PR17852. This reverts commit d93e8a06b2ca09ab18f390cd514b7443e2e571f7. Conflicts: test/Transforms/GVN/cond_br2.ll llvm-svn: 194348
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Matt Arsenault authored
This should be inconsequential and is work towards removing the default address space arguments. llvm-svn: 194347
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Nadav Rotem authored
SimplifyCFG has a heuristics for out-of-order processors that decides when it is worthwhile to merge branches. It tries to estimate if the operands of the instruction that we want to hoist are ready. This commit marks function arguments as 'ready' because they require no calculation. This boosts libquantum and a few other workloads from the testsuite. llvm-svn: 194346
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Matt Arsenault authored
llvm-svn: 194342
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- Nov 08, 2013
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Hal Finkel authored
LoopUnswitch's code simplification routine has logic to convert conditional branches into unconditional branches, after unswitching makes the condition constant, and then remove any blocks that renders dead. Unfortunately, this code is dead, currently broken, and furthermore, has never been alive (at least as far back at 2006). No functionality change intended. llvm-svn: 194277
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- Nov 05, 2013
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Michael Gottesman authored
[objc-arc] Convert the one directional retain/release relation assert to a conditional check + fail. Due to the previously added overflow checks, we can have a retain/release relation that is one directional. This occurs specifically when we run into an additive overflow causing us to drop state in only one direction. If that occurs, we should bail and not optimize that retain/release instead of asserting. Apologies for the size of the testcase. It is necessary to cause the additive cfg overflow to trigger. rdar://15377890 llvm-svn: 194083
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Hal Finkel authored
As with the other loop unrolling parameters (the unrolling threshold, partial unrolling, etc.) runtime unrolling can now also be controlled via the constructor. This will be necessary for moving non-trivial unrolling late in the pass manager (after loop vectorization). No functionality change intended. llvm-svn: 194027
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- Nov 04, 2013
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Shuxin Yang authored
llvm-svn: 194017
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Benjamin Kramer authored
STL debug mode checks this. llvm-svn: 194015
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Matt Arsenault authored
When the elements are extracted from a select on vectors or a vector select, do the select on the extracted scalars from the input if there is only one use. llvm-svn: 194013
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- Nov 03, 2013
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Benjamin Kramer authored
llvm-svn: 193958
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Benjamin Kramer authored
Instead of doing a RPO traversal of the whole function remember the blocks containing gathers (typically <= 2) and scan them in dominator-first order. The actual CSE is still quadratic, but I'm not confident that adding a scoped hash table here is worth it as we're only looking at the generated instructions and not arbitrary code. llvm-svn: 193956
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David Majnemer authored
This reverts commit r193356, it caused PR17781. A reduced test case covering this regression has been added to the test suite. llvm-svn: 193955
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