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* [SimplifyCFG] Simplify code review by temporarily removing this test file.Chad Rosier2016-04-221-478/+0
| | | | | | | A followup commit will replace these tests with simplified and more inclusive tests. The diff is unreadable if this were to be done in a single commit. llvm-svn: 267170
* [SimplifyCFG] Fold `llvm.guard(false)` to unreachableSanjoy Das2016-04-211-0/+86
| | | | | | | | | | | | | | Summary: `llvm.guard(false)` always bails out of the current compilation unit, so we can prune any control flow following it. Reviewers: hfinkel, pcc, reames Subscribers: majnemer, reames, mcrosier, llvm-commits Differential Revision: http://reviews.llvm.org/D19245 llvm-svn: 266955
* [LLVM] Remove unwanted --check-prefix=CHECK from unit tests. NFC.Mandeep Singh Grang2016-04-191-1/+1
| | | | | | | | | | | | Summary: Removed unwanted --check-prefix=CHECK from numerous unit tests. Reviewers: t.p.northover, dblaikie, uweigand, MatzeB, tstellarAMD, mcrosier Subscribers: mcrosier, dsanders Differential Revision: http://reviews.llvm.org/D19279 llvm-svn: 266834
* [ValueTracking] Improve isImpliedCondition for conditions with matching ↵Chad Rosier2016-04-191-0/+478
| | | | | | | | | | | | | | | operands. This patch improves SimplifyCFG to catch cases like: if (a < b) { if (a > b) <- known to be false unreachable; } Phabricator Revision: http://reviews.llvm.org/D18905 llvm-svn: 266767
* [PR27284] Reverse the ownership between DICompileUnit and DISubprogram.Adrian Prantl2016-04-154-9/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently each Function points to a DISubprogram and DISubprogram has a scope field. For member functions the scope is a DICompositeType. DIScopes point to the DICompileUnit to facilitate type uniquing. Distinct DISubprograms (with isDefinition: true) are not part of the type hierarchy and cannot be uniqued. This change removes the subprograms list from DICompileUnit and instead adds a pointer to the owning compile unit to distinct DISubprograms. This would make it easy for ThinLTO to strip unneeded DISubprograms and their transitively referenced debug info. Motivation ---------- Materializing DISubprograms is currently the most expensive operation when doing a ThinLTO build of clang. We want the DISubprogram to be stored in a separate Bitcode block (or the same block as the function body) so we can avoid having to expensively deserialize all DISubprograms together with the global metadata. If a function has been inlined into another subprogram we need to store a reference the block containing the inlined subprogram. Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script that updates LLVM IR testcases to the new format. http://reviews.llvm.org/D19034 <rdar://problem/25256815> llvm-svn: 266446
* [SimplifyCFG] propagate branch metadata when creating select (PR27344)Sanjay Patel2016-04-151-1/+1
| | | | | | | | | | This is almost identical to: http://reviews.llvm.org/rL264527 This doesn't solve PR27344; it just allows the profile weights to survive. To solve the bug, we need to use the profile weights in the backend. llvm-svn: 266442
* [SimplifyCFG] add metadata to show failure to propagate (PR27344)Sanjay Patel2016-04-151-7/+10
| | | | llvm-svn: 266435
* testcase gardening: update the emissionKind enum to the new syntax. (NFC)Adrian Prantl2016-04-014-4/+4
| | | | llvm-svn: 265081
* Move the DebugEmissionKind enum from DIBuilder into DICompileUnit.Adrian Prantl2016-03-313-3/+3
| | | | | | | | | | | | | This mostly cosmetic patch moves the DebugEmissionKind enum from DIBuilder into DICompileUnit. DIBuilder is not the right place for this enum to live in — a metadata consumer should not have to include DIBuilder.h. I also added a Verifier check that checks that the emission kind of a DICompileUnit is actually legal. http://reviews.llvm.org/D18612 <rdar://problem/25427165> llvm-svn: 265077
* [DebugInfo] Subprograms should belong to a CU.Davide Italiano2016-03-311-1/+1
| | | | | | | | Start fixing tests accordingly. There are still about 35 failures before we can enable this check in the IR verifier. llvm-svn: 264990
* Upgrade some wildly anachronistic debug info in testcases.Adrian Prantl2016-03-293-6/+4
| | | | llvm-svn: 264797
* [SimlifyCFG] Prevent passes from destroying canonical loop structure, ↵Hyojin Sung2016-03-293-34/+34
| | | | | | | | | | | | | | | | | especially for nested loops When eliminating or merging almost empty basic blocks, the existence of non-trivial PHI nodes is currently used to recognize potential loops of which the block is the header and keep the block. However, the current algorithm fails if the loops' exit condition is evaluated only with volatile values hence no PHI nodes in the header. Especially when such a loop is an outer loop of a nested loop, the loop is collapsed into a single loop which prevent later optimizations from being applied (e.g., transforming nested loops into simplified forms and loop vectorization). The patch augments the existing PHI node-based check by adding a pre-test if the BB actually belongs to a set of loop headers and not eliminating it if yes. llvm-svn: 264697
* regenerate checksSanjay Patel2016-03-283-74/+107
| | | | llvm-svn: 264677
* Revert "[SimlifyCFG] Prevent passes from destroying canonical loop ↵Reid Kleckner2016-03-282-32/+32
| | | | | | | | | | structure, especially for nested loops" This reverts commit r264596. It does not compile. llvm-svn: 264604
* [SimlifyCFG] Prevent passes from destroying canonical loop structure, ↵Hyojin Sung2016-03-282-32/+32
| | | | | | | | | | | | | | | | especially for nested loops When eliminating or merging almost empty basic blocks, the existence of non-trivial PHI nodes is currently used to recognize potential loops of which the block is the header and keep the block. However, the current algorithm fails if the loops' exit condition is evaluated only with volatile values hence no PHI nodes in the header. Especially when such a loop is an outer loop of a nested loop, the loop is collapsed into a single loop which prevent later optimizations from being applied (e.g., transforming nested loops into simplified forms and loop vectorization). The patch augments the existing PHI node-based check by adding a pre-test if the BB actually belongs to a set of loop headers and not eliminating it if yes. llvm-svn: 264596
* [SimplifyCFG] propagate branch metadata when creating select (PR26636)Sanjay Patel2016-03-261-2/+5
| | | | llvm-svn: 264527
* minimize test casesSanjay Patel2016-03-261-59/+38
| | | | | | | These are tests for store transforms. The loads, adds, and geps were irrelevant. llvm-svn: 264526
* propagate 'unpredictable' metadata on select instructions Sanjay Patel2016-03-171-2/+4
| | | | | | | | | | | | This is similar to D18133 where we allowed profile weights on select instructions. This extends that change to also allow the 'unpredictable' attribute of branches to apply to selects. A test to check that 'unpredictable' metadata is preserved when cloning instructions was checked in at: http://reviews.llvm.org/rL263648 Differential Revision: http://reviews.llvm.org/D18220 llvm-svn: 263716
* use FileCheck for tighter checkingSanjay Patel2016-03-161-4/+22
| | | | llvm-svn: 263679
* reduce check strings; no need to check IR commentsSanjay Patel2016-03-161-7/+7
| | | | llvm-svn: 263675
* use FileCheck for tighter checkingSanjay Patel2016-03-161-2/+36
| | | | | | | | I'm testing out a script that auto-generates the check lines. It's 98% copied from utils/update_llc_test_checks.py. If others think this is useful, please let me know. llvm-svn: 263668
* use FileCheck for tighter checkingSanjay Patel2016-03-161-7/+15
| | | | | | | | I'm testing out a script that auto-generates the check lines. It's 98% copied from utils/update_llc_test_checks.py. If others think this is useful, please let me know. llvm-svn: 263667
* allow branch weight metadata on select instructions (PR26636)Sanjay Patel2016-03-141-2/+9
| | | | | | | | | | | | | | | | | | | | | | | As noted in: https://llvm.org/bugs/show_bug.cgi?id=26636 This doesn't accomplish anything on its own. It's the first step towards preserving and using branch weights with selects. The next step would be to make sure we're propagating the info in all of the other places where we create selects (SimplifyCFG, InstCombine, etc). I don't think there's an easy fix to make this happen; we have to look at each transform individually to determine how to correctly propagate the weights. Along with that step, we need to then use the weights when making subsequent transform decisions such as discussed in http://reviews.llvm.org/D16836. The inliner test is independent but closely related. It verifies that metadata is preserved when both branches and selects are cloned. Differential Revision: http://reviews.llvm.org/D18133 llvm-svn: 263482
* update test to use FileCheckSanjay Patel2016-03-121-9/+17
| | | | llvm-svn: 263347
* [SimplifyCFG] Do not blindly remove unreachable blocksDavid Majnemer2016-02-241-0/+40
| | | | | | | | | | | DeleteDeadBlock was called indiscriminately, leading to cleanuprets with undef cleanuppad references. Instead, try to drain the BB of most of it's instructions if it is unreachable. We can then remove the BB if it solely consists of a terminator (and maybe some phis). llvm-svn: 261731
* [SimplifyCFG] Merge together cleanuppadsDavid Majnemer2016-02-201-0/+39
| | | | | | | | | | Cleanuppads may be merged together if one is the only predecessor of the other in which case a simple transform can be performed: replace the a cleanupret with a branch and remove an unnecessary cleanuppad. Differential Revision: http://reviews.llvm.org/D17459 llvm-svn: 261390
* [SimplifyCFG] Don't fold conditional branches that contain calls to ↵Justin Lebar2016-02-121-0/+28
| | | | | | | | | | | | | | | | convergent functions. Summary: Performing this optimization duplicates the call to the convergent function and adds new control-flow dependencies, which is a no-no. Reviewers: jingyue Subscribers: broune, hfinkel, tra, resistor, joker.eph, arsenm, llvm-commits, mzolotukhin Differential Revision: http://reviews.llvm.org/D17128 llvm-svn: 260730
* [SimplifyCFG] Fix for "endless" loop after dead code removal (Alternative toGerolf Hoflehner2016-02-031-0/+101
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | D16251) Summary: This is a simpler fix to the problem than the dominator approach in http://reviews.llvm.org/D16251. It adds only values into the gather() while loop that have been seen before. The actual endless loop is in the constant compare gather() routine in Utils/SimplifyCFG.cpp. The same value ret.0.off0.i is pushed back into the queue: %.ret.0.off0.i = or i1 %.ret.0.off0.i, %cmp10.i Here is what happens at the IR level: for.cond.i: ; preds = %if.end6.i, %if.end.i54 %ix.0.i = phi i32 [ 0, %if.end.i54 ], [ %inc.i55, %if.end6.i ] %ret.0.off0.i = phi i1 [false, %if.end.i54], [%.ret.0.off0.i, %if.end6.i] <<< %cmp2.i = icmp ult i32 %ix.0.i, %11 br i1 %cmp2.i, label %for.body.i, label %LBJ_TmpSimpleNeedExt.exit if.end6.i: ; preds = %for.body.i %cmp10.i = icmp ugt i32 %conv.i, %add9.i %.ret.0.off0.i = or i1 %ret.0.off0.i, %cmp10.i <<< When if.end.i54 gets eliminated which removes the definition of ret.0.off0.i. The result is the expression %.ret.0.off0.i = or i1 %.ret.0.off0.i, %cmp10.i (Note the first ‘or’ operand is now %.ret.0.off0.i, and *NOT* %ret.0.off0.i). And now there is use of .ret.0.off0.i before a definition which triggers the “endless” loop in gather(): while(!DFT.empty()) { V = DFT.pop_back_val(); // V is .ret.0.off0.i if (Instruction *I = dyn_cast<Instruction>(V)) { // If it is a || (or && depending on isEQ), process the operands. if (I->getOpcode() == (isEQ ? Instruction::Or : Instruction::And)) { DFT.push_back(I->getOperand(1)); // This is now .ret.0.off0.i also DFT.push_back(I->getOperand(0)); continue; // “endless loop” for .ret.0.off0.i } Reviewers: reames, ahatanak Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D16839 llvm-svn: 259730
* Tweak unnamed label syntax in textual IR for easier matching in tests.Evgeniy Stepanov2016-01-271-2/+2
| | | | | | | | | | | Change the unnamed label comments like ; <label>:8 ; preds = %1 to ; <label>:8: ; preds = %1 This way lit tests can match [[LABEL]]: in both asserts and no-asserts builds. llvm-svn: 258993
* [SimplifyCFG] limit recursion depth when speculating instructions (PR26308)Sanjay Patel2016-01-271-0/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | This is a fix for: https://llvm.org/bugs/show_bug.cgi?id=26308 With the switch to using the TTI cost model in: http://reviews.llvm.org/rL228826 ...it became possible to hit a zero-cost cycle of instructions (gep -> phi -> gep...), so we need a cap for the recursion in DominatesMergePoint(). A recursion depth parameter was already added for a different reason in: http://reviews.llvm.org/rL255660 ...so we can just set a limit for it. I pulled "10" out of the air and made it an independent parameter that we can play with. It might be higher than it needs to be given the currently low default value of PHINodeFoldingThreshold (2). That's the starting cost value that we enter the recursion with, and most instructions have cost set to TCC_Basic (1), so I don't think we're going to speculate more than 2 instructions with the current parameters. As noted in the review and the TODO comment, we can do better than just limiting recursion depth. Differential Revision: http://reviews.llvm.org/D16637 llvm-svn: 258971
* Revert "Revert "[SimplifyCFG] allow speculation of exactly one expensive ↵David Majnemer2016-01-272-43/+23
| | | | | | | | | instruction (PR24818)"" This reverts commit r258903 which reverted r255660. r258903 was an accidental commit and should not have been committed. llvm-svn: 258905
* [SimplifyCFG] Don't mistake icmp of and for a tree of comparisonsDavid Majnemer2016-01-271-0/+25
| | | | | | | | | | | | | | | | SimplifyCFG tries to turn complex branch conditions into a switch. Some of it's logic attempts to reason about bitwise arithmetic produced by InstCombine. InstCombine can turn things like (X == 2) || (X == 3) into (X & 1) == 2 and so SimplifyCFG tries to detect when this occurs so that it can produce a switch instruction. However, the legality checking was not sufficient to determine whether or not this had occured. Correctly check this case by requiring that the right-hand side of the comparison be a power of two. This fixes PR26323. llvm-svn: 258904
* Revert "[SimplifyCFG] allow speculation of exactly one expensive instruction ↵David Majnemer2016-01-272-23/+43
| | | | | | | | (PR24818)" This reverts commit r255660. llvm-svn: 258903
* [SimplifyCFG] Extend SimplifyResume to handle phi of trivial landing pad.Chen Li2016-01-102-0/+82
| | | | | | | | | | | | | | | | Summary: This is a fix of D13718. D13718 was committed but then reverted because of the following bug: https://llvm.org/bugs/show_bug.cgi?id=25299 This patch fixes the issue shown in the bug. Reviewers: majnemer, reames Subscribers: jevinskie, llvm-commits Differential Revision: http://reviews.llvm.org/D14308 llvm-svn: 257277
* [SimplifyCFG] Further improve our ability to remove redundant catchpadsDavid Majnemer2016-01-051-0/+66
| | | | | | | | | In r256814, we managed to remove catchpads which were trivially redudant because they were the same SSA value. We can do better using the same algorithm but with a smarter datastructure by hashing the SSA values within the catchpad and comparing them structurally. llvm-svn: 256815
* [SimplifyCFG] Remove redundant catchpadsDavid Majnemer2016-01-051-0/+18
| | | | | | Remove duplicate catchpad handlers from a catchswitch. llvm-svn: 256814
* [WinEH] Simplify unreachable catchpadsJoseph Tremoulet2016-01-051-0/+115
| | | | | | | | | | | | | | | | Summary: At least for CoreCLR, a catchpad which immediately executes an `unreachable` instruction indicates that the exception can never have a matching type, and so such catchpads can be removed, and so can their catchswitches if the catchswitch becomes empty. Reviewers: rnk, andrew.w.kaylor, majnemer Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D15846 llvm-svn: 256809
* [gc.statepoint] Change gc.statepoint intrinsic's return type to token type ↵Chen Li2015-12-261-3/+3
| | | | | | | | | | | | | | instead of i32 type Summary: This patch changes gc.statepoint intrinsic's return type to token type instead of i32 type. Using token types could prevent LLVM to merge different gc.statepoint nodes into PHI nodes and cause further problems with gc relocations. The patch also changes the way on how gc.relocate and gc.result look for their corresponding gc.statepoint on unwind path. The current implementation uses the selector value extracted from a { i8*, i32 } landingpad as a hook to find the gc.statepoint, while the patch directly uses a token type landingpad (http://reviews.llvm.org/D15405) to find the gc.statepoint. Reviewers: sanjoy, JosephTremoulet, pgavlin, igor-laevsky, mjacob Subscribers: reames, mjacob, sanjoy, llvm-commits Differential Revision: http://reviews.llvm.org/D15662 llvm-svn: 256443
* [SimplifyCFG] Don't create unnecessary PHIsJames Molloy2015-12-161-0/+215
| | | | | | | | | | | | | | In conditional store merging, we were creating PHIs when we didn't need to. If the value to be predicated isn't defined in the block we're predicating, then it doesn't need a PHI at all (because we only deal with triangles and diamonds, any value not in the predicated BB must dominate the predicated BB). This fixes a large code size increase in some benchmarks in a popular embedded benchmark suite. Now with a fix (and fixed tests) for the conformance issue seen in Chromium. llvm-svn: 255767
* [SimplifyCFG] allow speculation of exactly one expensive instruction (PR24818)Sanjay Patel2015-12-152-43/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the last general step to allow more IR-level speculation with a safety harness in place in CodeGenPrepare. The intent is to restore the behavior enabled by: http://reviews.llvm.org/rL228826 but prevent bad performance such as: https://llvm.org/bugs/show_bug.cgi?id=24818 Earlier patches in this sequence: D12882 (disable SimplifyCFG speculation for expensive instructions) D13297 (have CGP despeculate expensive ops) D14630 (have CGP despeculate special versions of cttz/ctlz) As shown in the test cases, we only have two instructions currently affected: ctz for some x86 and fdiv generally. Allowing exactly one expensive instruction is a bit of a hack, but it lines up with what is currently implemented in CGP. If we make the despeculation more general in CGP, we can make the speculation here more liberal. A follow-up patch will adjust the cost for sqrt and possibly other typically expensive math intrinsics (currently everything is cheap by default). GPU targets would likely want to override those expensive default costs (just as they probably should already override the cost of div/rem) because just about any math is cheaper than control-flow on those targets. Differential Revision: http://reviews.llvm.org/D15213 llvm-svn: 255660
* Revert "Don't create unnecessary PHIs"Reid Kleckner2015-12-142-200/+4
| | | | | | | | | This reverts commit r255489. It causes test failures in Chromium and does not appear to respect the AlternativeV parameter. llvm-svn: 255562
* [IR] Remove terminatepadDavid Majnemer2015-12-142-70/+0
| | | | | | | | | | | | | It turns out that terminatepad gives little benefit over a cleanuppad which calls the termination function. This is not sufficient to implement fully generic filters but MSVC doesn't support them which makes terminatepad a little over-designed. Depends on D15478. Differential Revision: http://reviews.llvm.org/D15479 llvm-svn: 255522
* Don't create unnecessary PHIsJames Molloy2015-12-142-4/+200
| | | | | | | | | | | | In conditional store merging, we were creating PHIs when we didn't need to. If the value to be predicated isn't defined in the block we're predicating, then it doesn't need a PHI at all (because we only deal with triangles and diamonds, any value not in the predicated BB must dominate the predicated BB). This fixes a large code size increase in some benchmarks in a popular embedded benchmark suite. llvm-svn: 255489
* [IR] Reformulate LLVM's EH funclet IRDavid Majnemer2015-12-122-115/+88
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While we have successfully implemented a funclet-oriented EH scheme on top of LLVM IR, our scheme has some notable deficiencies: - catchendpad and cleanupendpad are necessary in the current design but they are difficult to explain to others, even to seasoned LLVM experts. - catchendpad and cleanupendpad are optimization barriers. They cannot be split and force all potentially throwing call-sites to be invokes. This has a noticable effect on the quality of our code generation. - catchpad, while similar in some aspects to invoke, is fairly awkward. It is unsplittable, starts a funclet, and has control flow to other funclets. - The nesting relationship between funclets is currently a property of control flow edges. Because of this, we are forced to carefully analyze the flow graph to see if there might potentially exist illegal nesting among funclets. While we have logic to clone funclets when they are illegally nested, it would be nicer if we had a representation which forbade them upfront. Let's clean this up a bit by doing the following: - Instead, make catchpad more like cleanuppad and landingpad: no control flow, just a bunch of simple operands; catchpad would be splittable. - Introduce catchswitch, a control flow instruction designed to model the constraints of funclet oriented EH. - Make funclet scoping explicit by having funclet instructions consume the token produced by the funclet which contains them. - Remove catchendpad and cleanupendpad. Their presence can be inferred implicitly using coloring information. N.B. The state numbering code for the CLR has been updated but the veracity of it's output cannot be spoken for. An expert should take a look to make sure the results are reasonable. Reviewers: rnk, JosephTremoulet, andrew.w.kaylor Differential Revision: http://reviews.llvm.org/D15139 llvm-svn: 255422
* [OperandBundles] Fix a transform in simplifycfgSanjoy Das2015-12-081-0/+13
| | | | | | | | | | Reviewers: pcc, majnemer, reames Subscribers: reames, llvm-commits Differential Revision: http://reviews.llvm.org/D15345 llvm-svn: 255062
* Revert "Revert "Strip metadata when speculatively hoisting instructions ↵Igor Laevsky2015-11-181-0/+26
| | | | | | | | (r252604)" Failing clang test is now fixed by the r253458. llvm-svn: 253459
* [MIPS] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz()Sanjay Patel2015-11-112-0/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | MIPS32 has instructions for efficient count-leading/trailing-zeros, so this should be considered a cheap operation (and therefore fair game for speculation) for any MIPS32 implementation. The net result of allowing this speculation for the regression tests in this patch is that we get this code: ctlz: jr $ra clz $2, $4 cttz: addiu $1, $4, -1 not $2, $4 and $1, $2, $1 clz $1, $1 addiu $2, $zero, 32 jr $ra subu $2, $2, $1 Instead of: ctlz: beqz $4, $BB0_2 addiu $2, $zero, 32 clz $2, $4 $BB0_2: jr $ra nop cttz: beqz $4, $BB1_2 addiu $2, $zero, 32 addiu $1, $4, -1 not $2, $4 and $1, $2, $1 clz $1, $1 addiu $2, $zero, 32 subu $2, $2, $1 $BB1_2: jr $ra nop See D14469 for the larger motivation. Differential Revision: http://reviews.llvm.org/D14500 llvm-svn: 252755
* [ARM] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz()Sanjay Patel2015-11-102-0/+48
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ARM V6T2 has instructions for efficient count-leading/trailing-zeros, so this should be considered a cheap operation (and therefore fair game for speculation) for any ARM V6T2 implementation. The net result of allowing this speculation for the regression tests in this patch is that we get this code: ctlz: clz r0, r0 bx lr cttz: rbit r0, r0 clz r0, r0 bx lr Instead of: ctlz: cmp r0, #0 moveq r0, #32 clzne r0, r0 bx lr cttz: cmp r0, #0 moveq r0, #32 rbitne r0, r0 clzne r0, r0 bx lr This will help solve a general speculation/despeculation problem noted in PR24818: https://llvm.org/bugs/show_bug.cgi?id=24818 Differential Revision: http://reviews.llvm.org/D14469 llvm-svn: 252639
* [AArch64] add overrides for isCheapToSpeculateCttz() and ↵Sanjay Patel2015-11-101-0/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | isCheapToSpeculateCtlz() AArch64 has instructions for efficient count-leading/trailing-zeros, so this should be considered a cheap operation (and therefore fair game for speculation) for any AArch64 implementation. The net result of allowing this speculation for the regression tests in this patch is that we get this code: ctlz: clz w0, w0 ret cttz: rbit w8, w0 clz w0, w8 ret Instead of: ctlz: cbz w0, .LBB0_2 clz w0, w0 ret .LBB0_2: orr w0, wzr, #0x20 ret cttz: cbz w0, .LBB1_2 rbit w8, w0 clz w0, w8 ret .LBB1_2: orr w0, wzr, #0x20 ret See D14469 for the larger motivation. Differential Revision: http://reviews.llvm.org/D14505 llvm-svn: 252625
* Revert "Strip metadata when speculatively hoisting instructions"Renato Golin2015-11-101-26/+0
| | | | | | | This reverts commit r252604, as it broke all ARM and AArch64 buildbots, as well as some x86, et al. llvm-svn: 252623
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