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* fold: sqrt(x * x * y) -> fabs(x) * sqrt(y)Sanjay Patel2014-10-161-1/+87
| | | | | | | | | | | | | | | | | | | | | | | | | If a square root call has an FP multiplication argument that can be reassociated, then we can hoist a repeated factor out of the square root call and into a fabs(). In the simplest case, this: y = sqrt(x * x); becomes this: y = fabs(x); This patch relies on an earlier optimization in instcombine or reassociate to put the multiplication tree into a canonical form, so we don't have to search over every permutation of the multiplication tree. Because there are no IR-level FastMathFlags for intrinsics (PR21290), we have to use function-level attributes to do this optimization. This needs to be fixed for both the intrinsics and in the backend. Differential Revision: http://reviews.llvm.org/D5787 llvm-svn: 219944
* Preserve non-byval pointer alignment attributes using @llvm.assume when inliningHal Finkel2014-10-151-0/+45
| | | | | | | | | For pointer-typed function arguments, enhanced alignment can be asserted using the 'align' attribute. When inlining, if this enhanced alignment information is not otherwise available, preserve it using @llvm.assume-based alignment assumptions. llvm-svn: 219876
* Optimize away fabs() calls when input is squared (known positive).Sanjay Patel2014-10-141-1/+30
| | | | | | | | | | | | Eliminate library calls and intrinsic calls to fabs when the input is a squared value. Note that no unsafe-math / fast-math assumptions are needed for this optimization. Differential Revision: http://reviews.llvm.org/D5777 llvm-svn: 219717
* Switch to select optimization for two-case switchesMarcello Maggioni2014-10-141-0/+170
| | | | | | | This is the same optimization of r219233 with modifications to support PHIs with multiple incoming edges from the same block and a test to check that this condition is handled. llvm-svn: 219656
* Revert r219223, it creates invalid PHI nodes.Joerg Sonnenberger2014-10-121-170/+0
| | | | llvm-svn: 219587
* SimplifyCFG: Don't convert phis into selects if we could remove undef behaviorArnold Schwaighofer2014-10-101-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | instead We used to transform this: define void @test6(i1 %cond, i8* %ptr) { entry: br i1 %cond, label %bb1, label %bb2 bb1: br label %bb2 bb2: %ptr.2 = phi i8* [ %ptr, %entry ], [ null, %bb1 ] store i8 2, i8* %ptr.2, align 8 ret void } into this: define void @test6(i1 %cond, i8* %ptr) { %ptr.2 = select i1 %cond, i8* null, i8* %ptr store i8 2, i8* %ptr.2, align 8 ret void } because the simplifycfg transformation into selects would happen to happen before the simplifycfg transformation that removes unreachable control flow (We have 'unreachable control flow' due to the store to null which is undefined behavior). The existing transformation that removes unreachable control flow in simplifycfg is: /// If BB has an incoming value that will always trigger undefined behavior /// (eg. null pointer dereference), remove the branch leading here. static bool removeUndefIntroducingPredecessor(BasicBlock *BB) Now we generate: define void @test6(i1 %cond, i8* %ptr) { store i8 2, i8* %ptr.2, align 8 ret void } I did not see any impact on the test-suite + externals. rdar://18596215 llvm-svn: 219462
* LoopUnroll: Create sub-loops in LoopInfoDuncan P. N. Exon Smith2014-10-071-1/+29
| | | | | | | | | | | | | `LoopUnrollPass` says that it preserves `LoopInfo` -- make it so. In particular, tell `LoopInfo` about copies of inner loops when unrolling the outer loop. Conservatively, also tell `ScalarEvolution` to forget about the original versions of these loops, since their inputs may have changed. Fixes PR20987. llvm-svn: 219241
* LoopUnroll: Only check for ScalarEvolution analysis once, NFCDuncan P. N. Exon Smith2014-10-071-7/+4
| | | | | | | A follow-up commit will add use to a tight loop. We might as well just find it once anyway. llvm-svn: 219239
* Two case switch to select optimizationMarcello Maggioni2014-10-071-0/+170
| | | | | | | | | | | | | | | | | | | | | This optimization tries to convert switch instructions that are used to select a value with only 2 unique cases + default block to a select or a couple of selects (depending if the default block is reachable or not). The typical case this optimization wants to be able to optimize is this one: Example: switch (a) { case 10: %0 = icmp eq i32 %a, 10 return 10; %1 = select i1 %0, i32 10, i32 4 case 20: ----> %2 = icmp eq i32 %a, 20 return 2; %3 = select i1 %2, i32 2, i32 %1 default: return 4; } It also sets the base for further optimizations that are planned and being reviewed. llvm-svn: 219223
* LoopUnroll: Change code order of changes to new basic blocksDuncan P. N. Exon Smith2014-10-061-2/+2
| | | | | | | Add new basic blocks to `LoopInfo` earlier. No functionality change intended (simplifies upcoming bugfix patch). llvm-svn: 219150
* Sink comment, NFCDuncan P. N. Exon Smith2014-10-061-2/+2
| | | | llvm-svn: 219149
* DIBuilder: Encapsulate DIExpression's element typeDuncan P. N. Exon Smith2014-10-011-4/+3
| | | | | | | | `DIExpression`'s elements are 64-bit integers that are stored as `ConstantInt`. The accessors already encapsulate the storage. This commit updates the `DIBuilder` API to also encapsulate that. llvm-svn: 218797
* Move the complex address expression out of DIVariable and into an extraAdrian Prantl2014-10-011-20/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | argument of the llvm.dbg.declare/llvm.dbg.value intrinsics. Previously, DIVariable was a variable-length field that has an optional reference to a Metadata array consisting of a variable number of complex address expressions. In the case of OpPiece expressions this is wasting a lot of storage in IR, because when an aggregate type is, e.g., SROA'd into all of its n individual members, the IR will contain n copies of the DIVariable, all alike, only differing in the complex address reference at the end. By making the complex address into an extra argument of the dbg.value/dbg.declare intrinsics, all of the pieces can reference the same variable and the complex address expressions can be uniqued across the CU, too. Down the road, this will allow us to move other flags, such as "indirection" out of the DIVariable, too. The new intrinsics look like this: declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr) declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr) This patch adds a new LLVM-local tag to DIExpressions, so we can detect and pretty-print DIExpression metadata nodes. What this patch doesn't do: This patch does not touch the "Indirect" field in DIVariable; but moving that into the expression would be a natural next step. http://reviews.llvm.org/D4919 rdar://problem/17994491 Thanks to dblaikie and dexonsmith for reviewing this patch! Note: I accidentally committed a bogus older version of this patch previously. llvm-svn: 218787
* Revert r218778 while investigating buldbot breakage.Adrian Prantl2014-10-011-19/+20
| | | | | | "Move the complex address expression out of DIVariable and into an extra" llvm-svn: 218782
* Move the complex address expression out of DIVariable and into an extraAdrian Prantl2014-10-011-20/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | argument of the llvm.dbg.declare/llvm.dbg.value intrinsics. Previously, DIVariable was a variable-length field that has an optional reference to a Metadata array consisting of a variable number of complex address expressions. In the case of OpPiece expressions this is wasting a lot of storage in IR, because when an aggregate type is, e.g., SROA'd into all of its n individual members, the IR will contain n copies of the DIVariable, all alike, only differing in the complex address reference at the end. By making the complex address into an extra argument of the dbg.value/dbg.declare intrinsics, all of the pieces can reference the same variable and the complex address expressions can be uniqued across the CU, too. Down the road, this will allow us to move other flags, such as "indirection" out of the DIVariable, too. The new intrinsics look like this: declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr) declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr) This patch adds a new LLVM-local tag to DIExpressions, so we can detect and pretty-print DIExpression metadata nodes. What this patch doesn't do: This patch does not touch the "Indirect" field in DIVariable; but moving that into the expression would be a natural next step. http://reviews.llvm.org/D4919 rdar://problem/17994491 Thanks to dblaikie and dexonsmith for reviewing this patch! llvm-svn: 218778
* C API: Add LLVMCloneModule()Tom Stellard2014-10-011-0/+9
| | | | llvm-svn: 218775
* [SimplifyCFG] threshold for folding branches with common destinationJingyue Wu2014-09-301-66/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This patch adds a threshold that controls the number of bonus instructions allowed for folding branches with common destination. The original code allows at most one bonus instruction. With this patch, users can customize the threshold to allow multiple bonus instructions. The default threshold is still 1, so that the code behaves the same as before when users do not specify this threshold. The motivation of this change is that tuning this threshold significantly (up to 25%) improves the performance of some CUDA programs in our internal code base. In general, branch instructions are very expensive for GPU programs. Therefore, it is sometimes worth trading more arithmetic computation for a more straightened control flow. Here's a reduced example: __global__ void foo(int a, int b, int c, int d, int e, int n, const int *input, int *output) { int sum = 0; for (int i = 0; i < n; ++i) sum += (((i ^ a) > b) && (((i | c ) ^ d) > e)) ? 0 : input[i]; *output = sum; } The select statement in the loop body translates to two branch instructions "if ((i ^ a) > b)" and "if (((i | c) ^ d) > e)" which share a common destination. With the default threshold, SimplifyCFG is unable to fold them, because computing the condition of the second branch "(i | c) ^ d > e" requires two bonus instructions. With the threshold increased, SimplifyCFG can fold the two branches so that the loop body contains only one branch, making the code conceptually look like: sum += (((i ^ a) > b) & (((i | c ) ^ d) > e)) ? 0 : input[i]; Increasing the threshold significantly improves the performance of this particular example. In the configuration where both conditions are guaranteed to be true, increasing the threshold from 1 to 2 improves the performance by 18.24%. Even in the configuration where the first condition is false and the second condition is true, which favors shortcuts, increasing the threshold from 1 to 2 still improves the performance by 4.35%. We are still looking for a good threshold and maybe a better cost model than just counting the number of bonus instructions. However, according to the above numbers, we think it is at least worth adding a threshold to enable more experiments and tuning. Let me know what you think. Thanks! Test Plan: Added one test case to check the threshold is in effect Reviewers: nadav, eliben, meheff, resistor, hfinkel Reviewed By: hfinkel Subscribers: hfinkel, llvm-commits Differential Revision: http://reviews.llvm.org/D5529 llvm-svn: 218711
* Use a loop to simplify the runtime unrolling prologue.Kevin Qin2014-09-291-118/+130
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Runtime unrolling will create a prologue to execute the extra iterations which is can't divided by the unroll factor. It generates an if-then-else sequence to jump into a factor -1 times unrolled loop body, like extraiters = tripcount % loopfactor if (extraiters == 0) jump Loop: if (extraiters == loopfactor) jump L1 if (extraiters == loopfactor-1) jump L2 ... L1: LoopBody; L2: LoopBody; ... if tripcount < loopfactor jump End Loop: ... End: It means if the unroll factor is 4, the loop body will be 7 times unrolled, 3 are in loop prologue, and 4 are in the loop. This commit is to use a loop to execute the extra iterations in prologue, like extraiters = tripcount % loopfactor if (extraiters == 0) jump Loop: else jump Prol Prol: LoopBody; extraiters -= 1 // Omitted if unroll factor is 2. if (extraiters != 0) jump Prol: // Omitted if unroll factor is 2. if (tripcount < loopfactor) jump End Loop: ... End: Then when unroll factor is 4, the loop body will be copied by only 5 times, 1 in the prologue loop, 4 in the original loop. And if the unroll factor is 2, new loop won't be created, just as the original solution. llvm-svn: 218604
* GlobalOpt: Preserve comdats of unoptimized initializersReid Kleckner2014-09-231-45/+26
| | | | | | | | | | | | | Rather than slurping in and splatting out the whole ctor list, preserve the existing array entries without trying to understand them. Only remove the entries that we know we can optimize away. This way we don't need to wire through priority and comdats or anything else we might add. Fixes a linker issue where the .init_array or .ctors entry would point to discarded initialization code if the comdat group from the TU with the faulty global_ctors entry was dropped. llvm-svn: 218337
* Fixing a build error.Chris Bieneman2014-09-171-1/+1
| | | | llvm-svn: 217983
* Refactoring SimplifyLibCalls to remove static initializers and generally ↵Chris Bieneman2014-09-171-1878/+1643
| | | | | | | | | | | | | | | | cleaning up the code. Summary: This eliminates ~200 lines of code mostly file scoped struct definitions that were unnecessary. Reviewers: chandlerc, resistor Reviewed By: resistor Subscribers: morisset, resistor, llvm-commits Differential Revision: http://reviews.llvm.org/D5364 llvm-svn: 217982
* Remove dead code in SimplifyCFGJingyue Wu2014-09-151-43/+0
| | | | | | | | | | | | | | | | | | | | | | | Summary: UsedByBranch is always true according to how BonusInst is defined. Test Plan: Passes check-all, and also verified if (BonusInst && !UsedByBranch) { ... } is never entered during check-all. Reviewers: resistor, nadav, jingyue Reviewed By: jingyue Subscribers: llvm-commits, eliben, meheff Differential Revision: http://reviews.llvm.org/D5324 llvm-svn: 217824
* Simplify code. No functionality change.Benjamin Kramer2014-09-131-15/+3
| | | | llvm-svn: 217726
* Make use of @llvm.assume in ValueTracking (computeKnownBits, etc.)Hal Finkel2014-09-078-51/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change, which allows @llvm.assume to be used from within computeKnownBits (and other associated functions in ValueTracking), adds some (optional) parameters to computeKnownBits and friends. These functions now (optionally) take a "context" instruction pointer, an AssumptionTracker pointer, and also a DomTree pointer, and most of the changes are just to pass this new information when it is easily available from InstSimplify, InstCombine, etc. As explained below, the significant conceptual change is that known properties of a value might depend on the control-flow location of the use (because we care that the @llvm.assume dominates the use because assumptions have control-flow dependencies). This means that, when we ask if bits are known in a value, we might get different answers for different uses. The significant changes are all in ValueTracking. Two main changes: First, as with the rest of the code, new parameters need to be passed around. To make this easier, I grouped them into a structure, and I made internal static versions of the relevant functions that take this structure as a parameter. The new code does as you might expect, it looks for @llvm.assume calls that make use of the value we're trying to learn something about (often indirectly), attempts to pattern match that expression, and uses the result if successful. By making use of the AssumptionTracker, the process of finding @llvm.assume calls is not expensive. Part of the structure being passed around inside ValueTracking is a set of already-considered @llvm.assume calls. This is to prevent a query using, for example, the assume(a == b), to recurse on itself. The context and DT params are used to find applicable assumptions. An assumption needs to dominate the context instruction, or come after it deterministically. In this latter case we only handle the specific case where both the assumption and the context instruction are in the same block, and we need to exclude assumptions from being used to simplify their own ephemeral values (those which contribute only to the assumption) because otherwise the assumption would prove its feeding comparison trivial and would be removed. This commit adds the plumbing and the logic for a simple masked-bit propagation (just enough to write a regression test). Future commits add more patterns (and, correspondingly, more regression tests). llvm-svn: 217342
* Add an Assumption-Tracking PassHal Finkel2014-09-072-1/+13
| | | | | | | | | | | | | | | | | | | | | | | | This adds an immutable pass, AssumptionTracker, which keeps a cache of @llvm.assume call instructions within a module. It uses callback value handles to keep stale functions and intrinsics out of the map, and it relies on any code that creates new @llvm.assume calls to notify it of the new instructions. The benefit is that code needing to find @llvm.assume intrinsics can do so directly, without scanning the function, thus allowing the cost of @llvm.assume handling to be negligible when none are present. The current design is intended to be lightweight. We don't keep track of anything until we need a list of assumptions in some function. The first time this happens, we scan the function. After that, we add/remove @llvm.assume calls from the cache in response to registration calls and ValueHandle callbacks. There are no new direct test cases for this pass, but because it calls it validation function upon module finalization, we'll pick up detectable inconsistencies from the other tests that touch @llvm.assume calls. This pass will be used by follow-up commits that make use of @llvm.assume. llvm-svn: 217334
* Enable noalias metadata by default and swap the order of the SLP and Loop ↵James Molloy2014-09-041-1/+1
| | | | | | | | vectorizers by default. After some time maturing, hopefully the flags themselves will be removed. llvm-svn: 217144
* Feed AA to the inliner and use AA->getModRefBehavior in AddAliasScopeMetadataHal Finkel2014-09-011-11/+17
| | | | | | | | | | | | This feeds AA through the IFI structure into the inliner so that AddAliasScopeMetadata can use AA->getModRefBehavior to figure out which functions only access their arguments (instead of just hard-coding some knowledge of memory intrinsics). Most of the information is only available from BasicAA; this is important for preserving alias scoping information for target-specific intrinsics when doing the noalias parameter attribute to metadata conversion. llvm-svn: 216866
* Fix AddAliasScopeMetadata again - alias.scope must be a complete descriptionHal Finkel2014-09-011-15/+37
| | | | | | | | | | | | | | | | | | | | | | | I thought that I had fixed this problem in r216818, but I did not do a very good job. The underlying issue is that when we add alias.scope metadata we are asserting that this metadata completely describes the aliasing relationships within the current aliasing scope domain, and so in the context of translating noalias argument attributes, the pointers must all be based on noalias arguments (as underlying objects) and have no other kind of underlying object. In r216818 excluding appropriate accesses from getting alias.scope metadata is done by looking for underlying objects that are not identified function-local objects -- but that's wrong because allocas, etc. are also function-local objects and we need to explicitly check that all underlying objects are the noalias arguments for which we're adding metadata aliasing scopes. This fixes the underlying-object check for adding alias.scope metadata, and does some refactoring of the related capture-checking eligibility logic (and adds more comments; hopefully making everything a bit clearer). Fixes self-hosting on x86_64 with -mllvm -enable-noalias-to-md-conversion (the feature is still disabled by default). llvm-svn: 216863
* Fix AddAliasScopeMetadata to not add scopes when deriving from unknown pointersHal Finkel2014-08-301-25/+51
| | | | | | | | | | | | | | | | | | | | | | | The previous implementation of AddAliasScopeMetadata, which adds noalias metadata to preserve noalias parameter attribute information when inlining had a flaw: it would add alias.scope metadata to accesses which might have been derived from pointers other than noalias function parameters. This was incorrect because even some access known not to alias with all noalias function parameters could easily alias with an access derived from some other pointer. Instead, when deriving from some unknown pointer, we cannot add alias.scope metadata at all. This fixes a miscompile of the test-suite's tramp3d-v4. Furthermore, we cannot add alias.scope to functions unless we know they access only argument-derived pointers (currently, we know this only for memory intrinsics). Also, we fix a theoretical problem with using the NoCapture attribute to skip the capture check. This is incorrect (as explained in the comment added), but would not matter in any code generated by Clang because we get only inferred nocapture attributes in Clang-generated IR. This functionality is not yet enabled by default. llvm-svn: 216818
* Fix a typo in AddAliasScopeMetadataHal Finkel2014-08-291-1/+1
| | | | llvm-svn: 216741
* Simplify creation of a bunch of ArrayRefs by using None, makeArrayRef or ↵Craig Topper2014-08-273-16/+8
| | | | | | just letting them be implicitly created. llvm-svn: 216525
* Remove dangling initializers in GlobalDCEBruno Cardoso Lopes2014-08-251-0/+3
| | | | | | | | | | | | | | GlobalDCE deletes global vars and updates their initializers to nullptr while leaving underlying constants to be cleaned up later by its uses. The clean up may never happen, fix this by forcing it every time it's safe to destroy constants. Final patch by Rafael Espindola http://reviews.llvm.org/D4931 <rdar://problem/17523868> llvm-svn: 216390
* Use range based for loops to avoid needing to re-mention SmallPtrSet size.Craig Topper2014-08-243-15/+10
| | | | llvm-svn: 216351
* Use DILexicalBlockFile, rather than DILexicalBlock, to track discriminator ↵David Blaikie2014-08-211-4/+2
| | | | | | | | | | | | | | | changes to ensure discriminator changes don't introduce new DWARF DW_TAG_lexical_blocks. Somewhat unnoticed in the original implementation of discriminators, but it could cause instructions to end up in new, small, DW_TAG_lexical_blocks due to the use of DILexicalBlock to track discriminator changes. Instead, use DILexicalBlockFile which we already use to track file changes without introducing new scopes, so it works well to track discriminator changes in the same way. llvm-svn: 216239
* Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid ↵Craig Topper2014-08-216-10/+10
| | | | | | needing to mention the size. llvm-svn: 216158
* Revert "Repace SmallPtrSet with SmallPtrSetImpl in function arguments to ↵Craig Topper2014-08-186-10/+10
| | | | | | | | avoid needing to mention the size." Getting a weird buildbot failure that I need to investigate. llvm-svn: 215870
* Repace SmallPtrSet with SmallPtrSetImpl in function arguments to avoid ↵Craig Topper2014-08-176-10/+10
| | | | | | needing to mention the size. llvm-svn: 215868
* Introduce a helper to combine instruction metadata.Rafael Espindola2014-08-152-0/+44
| | | | | | | | | Replace the old code in GVN and BBVectorize with it. Update SimplifyCFG to use it. Patch by Björn Steinbrink! llvm-svn: 215723
* Copy noalias metadata from call sites to inlined instructionsHal Finkel2014-08-141-4/+28
| | | | | | | | | | | | | | When a call site with noalias metadata is inlined, that metadata can be propagated directly to the inlined instructions (only those that might access memory because it is not useful on the others). Prior to inlining, the noalias metadata could express that a call would not alias with some other memory access, which implies that no instruction within that called function would alias. By propagating the metadata to the inlined instructions, we preserve that knowledge. This should complete the enhancements requested in PR20500. llvm-svn: 215676
* Add noalias metadata for general calls (not just memory intrinsics) during ↵Hal Finkel2014-08-141-7/+18
| | | | | | | | | | | | | | | | inlining When preserving noalias function parameter attributes by adding noalias metadata in the inliner, we should do this for general function calls (not just memory intrinsics). The logic is very similar to what already existed (except that we want to add this metadata even for functions taking no relevant parameters). This metadata can be used by ModRef queries in the caller after inlining. This addresses the first part of PR20500. Adding noalias metadata during inlining is still turned off by default. llvm-svn: 215657
* utils: Fix segfault in flattencfgJan Vesely2014-08-131-4/+5
| | | | | | | | | | | | | | v2: continue iterating through the rest of the bb use for loop v3: initialize FlattenCFG pass in ScalarOps add test v4: split off initializing flattencfg to a separate patch add comment Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu> llvm-svn: 215574
* Move helper for getting a terminating musttail call to BasicBlockReid Kleckner2014-08-121-30/+5
| | | | | | | | | | | No functional change. To be used in future commits that need to look for such instructions. Reviewed By: rafael Differential Revision: http://reviews.llvm.org/D4504 llvm-svn: 215413
* [SimplifyCFG] fix accessing deleted PHINodes in switch-to-table conversion.Manman Ren2014-08-021-1/+4
| | | | | | | | | When we have a covered lookup table, make sure we don't delete PHINodes that are cached in PHIs. rdar://17887153 llvm-svn: 214642
* SimplifyCFG: Avoid miscompilations due to removed lifetime intrinsics.Rafael Espindola2014-07-301-1/+1
| | | | | | | | | | | The lifetime intrinsics need some work in order to make it clear which optimizations are or are not valid. For now dropping this optimization avoids a miscompilation. Patch by Björn Steinbrink. llvm-svn: 214336
* Add @llvm.assume, lowering, and some basic propertiesHal Finkel2014-07-251-0/+28
| | | | | | | | | | | | | | | | | This is the first commit in a series that add an @llvm.assume intrinsic which can be used to provide the optimizer with a condition it may assume to be true (when the control flow would hit the intrinsic call). Some basic properties are added here: - llvm.invariant(true) is dead. - llvm.invariant(false) is unreachable (this directly corresponds to the documented behavior of MSVC's __assume(0)), so is llvm.invariant(undef). The intrinsic is tagged as writing arbitrarily, in order to maintain control dependencies. BasicAA has been updated, however, to return NoModRef for any particular location-based query so that we don't unnecessarily block code motion. llvm-svn: 213973
* Convert noalias parameter attributes into noalias metadata during inliningHal Finkel2014-07-251-0/+174
| | | | | | | | | | | | | | | | | | | | | | | This functionality is currently turned off by default. Part of the motivation for introducing scoped-noalias metadata is to enable the preservation of noalias parameter attribute information after inlining. Sometimes this can be inferred from the code in the caller after inlining, but often we simply lose valuable information. The overall process if fairly simple: 1. Create a new unqiue scope domain. 2. For each (used) noalias parameter, create a new alias scope. 3. For each pointer, collect the underlying objects. Add a noalias scope for each noalias parameter from which we're not derived (and has not been captured prior to that point). 4. Add an alias.scope for each noalias parameter from which we might be derived (or has been captured before that point). Note that the capture checks apply only if one of the underlying objects is not an identified function-local object. llvm-svn: 213949
* Feedback from Hans on r213815. No functionaility change.Manman Ren2014-07-241-10/+11
| | | | llvm-svn: 213895
* Add scoped-noalias metadataHal Finkel2014-07-241-0/+101
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds scoped noalias metadata. The primary motivations for this feature are: 1. To preserve noalias function attribute information when inlining 2. To provide the ability to model block-scope C99 restrict pointers Neither of these two abilities are added here, only the necessary infrastructure. In fact, there should be no change to existing functionality, only the addition of new features. The logic that converts noalias function parameters into this metadata during inlining will come in a follow-up commit. What is added here is the ability to generally specify noalias memory-access sets. Regarding the metadata, alias-analysis scopes are defined similar to TBAA nodes: !scope0 = metadata !{ metadata !"scope of foo()" } !scope1 = metadata !{ metadata !"scope 1", metadata !scope0 } !scope2 = metadata !{ metadata !"scope 2", metadata !scope0 } !scope3 = metadata !{ metadata !"scope 2.1", metadata !scope2 } !scope4 = metadata !{ metadata !"scope 2.2", metadata !scope2 } Loads and stores can be tagged with an alias-analysis scope, and also, with a noalias tag for a specific scope: ... = load %ptr1, !alias.scope !{ !scope1 } ... = load %ptr2, !alias.scope !{ !scope1, !scope2 }, !noalias !{ !scope1 } When evaluating an aliasing query, if one of the instructions is associated with an alias.scope id that is identical to the noalias scope associated with the other instruction, or is a descendant (in the scope hierarchy) of the noalias scope associated with the other instruction, then the two memory accesses are assumed not to alias. Note that is the first element of the scope metadata is a string, then it can be combined accross functions and translation units. The string can be replaced by a self-reference to create globally unqiue scope identifiers. [Note: This overview is slightly stylized, since the metadata nodes really need to just be numbers (!0 instead of !scope0), and the scope lists are also global unnamed metadata.] Existing noalias metadata in a callee is "cloned" for use by the inlined code. This is necessary because the aliasing scopes are unique to each call site (because of possible control dependencies on the aliasing properties). For example, consider a function: foo(noalias a, noalias b) { *a = *b; } that gets inlined into bar() { ... if (...) foo(a1, b1); ... if (...) foo(a2, b2); } -- now just because we know that a1 does not alias with b1 at the first call site, and a2 does not alias with b2 at the second call site, we cannot let inlining these functons have the metadata imply that a1 does not alias with b2. llvm-svn: 213864
* Fixing an MSVC conversion warning about implicitly converting the shift ↵Aaron Ballman2014-07-241-1/+1
| | | | | | results to 64-bits. No functional change intended. llvm-svn: 213863
* SimplifyCFG: fix a bug in switch to table conversionManman Ren2014-07-231-4/+13
| | | | | | | | | | | | | | | | | | | We use gep to access the global array "switch.table", and the table index should be treated as unsigned. When the highest bit is 1, this commit zero-extends the index to an integer type with larger size. For a switch on i2, we used to generate: %switch.tableidx = sub i2 %0, -2 getelementptr inbounds [4 x i64]* @switch.table, i32 0, i2 %switch.tableidx It is incorrect when %switch.tableidx is 2 or 3. The fix is to generate %switch.tableidx = sub i2 %0, -2 %switch.tableidx.zext = zext i2 %switch.tableidx to i3 getelementptr inbounds [4 x i64]* @switch.table, i32 0, i3 %switch.tableidx.zext rdar://17735071 llvm-svn: 213815
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