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* [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
* Strip metadata when speculatively hoisting instructionsIgor Laevsky2015-11-101-0/+26
| | | | | | | | | | | | | | | | This is fix for PR24059. When we are hoisting instruction above some condition it may turn out that metadata on this instruction was control dependant on the condition. This metadata becomes invalid and we need to drop it. This patch should cover most obvious places of speculative execution (which I have found by greping isSafeToSpeculativelyExecute). I think there are more cases but at least this change covers the severe ones. Differential Revision: http://reviews.llvm.org/D14398 llvm-svn: 252604
* DI: Reverse direction of subprogram -> function edge.Peter Collingbourne2015-11-053-6/+6
| | | | | | | | | | | | | | | | | | | | | | | Previously, subprograms contained a metadata reference to the function they described. Because most clients need to get or set a subprogram for a given function rather than the other way around, this created unneeded inefficiency. For example, many passes needed to call the function llvm::makeSubprogramMap() to build a mapping from functions to subprograms, and the IR linker needed to fix up function references in a way that caused quadratic complexity in the IR linking phase of LTO. This change reverses the direction of the edge by storing the subprogram as function-level metadata and removing DISubprogram's function field. Since this is an IR change, a bitcode upgrade has been provided. Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is attached to the PR. Differential Revision: http://reviews.llvm.org/D14265 llvm-svn: 252219
* [SimplifyCFG] Merge conditional storesJames Molloy2015-11-041-0/+241
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can often end up with conditional stores that cannot be speculated. They can come from fairly simple, idiomatic code: if (c & flag1) *a = x; if (c & flag2) *a = y; ... There is no dominating or post-dominating store to a, so it is not legal to move the store unconditionally to the end of the sequence and cache the intermediate result in a register, as we would like to. It is, however, legal to merge the stores together and do the store once: tmp = undef; if (c & flag1) tmp = x; if (c & flag2) tmp = y; if (c & flag1 || c & flag2) *a = tmp; The real power in this optimization is that it allows arbitrary length ladders such as these to be completely and trivially if-converted. The typical code I'd expect this to trigger on often uses binary-AND with constants as the condition (as in the above example), which means the ending condition can simply be truncated into a single binary-AND too: 'if (c & (flag1|flag2))'. As in the general case there are bitwise operators here, the ladder can often be optimized further too. This optimization involves potentially increasing register pressure. Even in the simplest case, the lifetime of the first predicate is extended. This can be elided in some cases such as using binary-AND on constants, but not in the general case. Threading 'tmp' through all branches can also increase register pressure. The optimization as in this patch is enabled by default but kept in a very conservative mode. It will only optimize if it thinks the resultant code should be if-convertable, and additionally if it can thread 'tmp' through at least one existing PHI, so it will only ever in the worst case create one more PHI and extend the lifetime of a predicate. This doesn't trigger much in LNT, unfortunately, but it does trigger in a big way in a third party test suite. llvm-svn: 252051
* Preserve load alignment and dereferenceable metadata during some transformationsArtur Pilipenko2015-11-023-0/+96
| | | | | | | | Reviewed By: hfinkel Differential Revision: http://reviews.llvm.org/D13953 llvm-svn: 251809
* [SimplifyCFG] Constant fold a branch implied by it's incoming edgePhilip Reames2015-10-291-0/+81
| | | | | | | | | | | The most common use case is when eliminating redundant range checks in an example like the following: c = a[i+1] + a[i]; Note that all the smarts of the transform (the implication engine) is already in ValueTracking and is tested directly through InstructionSimplify. Differential Revision: http://reviews.llvm.org/D13040 llvm-svn: 251596
* [SimplifyCFG] Don't DCE catchret because the successor is unreachableDavid Majnemer2015-10-271-0/+20
| | | | | | | CatchReturnInst has side-effects: it runs a destructor. This destructor could conceivably run forever/call exit/etc. and should not be removed. llvm-svn: 251461
* Revert rL251061 [SimplifyCFG] Extend SimplifyResume to handle phi of trivial ↵Chen Li2015-10-231-42/+0
| | | | | | landing pad. llvm-svn: 251149
* [SimplifyCFG] Extend SimplifyResume to handle phi of trivial landing pad.Chen Li2015-10-221-0/+42
| | | | | | | | | | | | Summary: Currently SimplifyResume can convert an invoke instruction to a call instruction if its landing pad is trivial. In practice we could have several invoke instructions with trivial landing pads and share a common rethrow block, and in the common rethrow block, all the landing pads join to a phi node. The patch extends SimplifyResume to check the phi of landing pad and their incoming blocks. If any of them is trivial, remove it from the phi node and convert the invoke instruction to a call instruction. Reviewers: hfinkel, reames Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D13718 llvm-svn: 251061
* [SimplifyCFG] Don't use-after-free an SSA valueDavid Majnemer2015-10-211-0/+24
| | | | | | | | | SimplifyTerminatorOnSelect didn't consider the possibility that the condition might be related to one of PHI nodes. This fixes PR25267. llvm-svn: 250922
* Revert 250343 and 250344Philip Reames2015-10-151-86/+0
| | | | | | | | | | | | | | | | | | | | | | | | Turns out this approach is buggy. In discussion about follow on work, Sanjoy pointed out that we could be subject to circular logic problems. Consider: if (i u< L) leave() if ((i + 1) u< L) leave() print(a[i] + a[i+1]) If we know that L is less than UINT_MAX, we could possible prove (in a control dependent way) that i + 1 does not overflow. This gives us: if (i u< L) leave() if ((i +nuw 1) u< L) leave() print(a[i] + a[i+1]) If we now do the transform this patch proposed, we end up with: if ((i +nuw 1) u< L) leave_appropriately() print(a[i] + a[i+1]) That would be a miscompile when i==-1. The problem here is that the control dependent nuw bits got used to prove something about the first condition. That's obviously invalid. This won't happen today, but since I plan to enhance LVI/CVP with exactly that transform at some point in the not too distant future... llvm-svn: 250430
* Test case which should have been part of 250343Philip Reames2015-10-141-0/+86
| | | | llvm-svn: 250344
* [asan] Disabling speculative loads under asan. Patch by Mike AizatskyKostya Serebryany2015-10-141-0/+40
| | | | llvm-svn: 250259
* [EH] Create removeUnwindEdge utilityJoseph Tremoulet2015-09-271-0/+88
| | | | | | | | | | | | | | | | | Summary: Factor the code that rewrites invokes to calls and rewrites WinEH terminators to their "unwind to caller" equivalents into a helper in Utils/Local, and use it in the three places I'm aware of that need to do this. Reviewers: andrew.w.kaylor, majnemer, rnk Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D13152 llvm-svn: 248677
* set div/rem default values to 'expensive' in TargetTransformInfo's cost modelSanjay Patel2015-09-231-0/+27
| | | | | | | | | | | | | | | | | | | ...because that's what the cost model was intended to do. As discussed in D12882, this fix has a temporary unintended consequence for SimplifyCFG: it causes us to not speculate an fdiv. However, two wrongs make PR24818 right, and two wrongs make PR24343 act right even though it's really still wrong. I intend to correct SimplifyCFG and add to CodeGenPrepare to account for this cost model change and preserve the righteousness for the bug report cases. https://llvm.org/bugs/show_bug.cgi?id=24818 https://llvm.org/bugs/show_bug.cgi?id=24343 Differential Revision: http://reviews.llvm.org/D12882 llvm-svn: 248439
* [WinEH] Pull Adjectives and CatchObj out of the catchpad arg listReid Kleckner2015-09-161-7/+7
| | | | | | | | | | Clang now passes the adjectives as an argument to catchpad. Getting the CatchObj working is simply a matter of threading another static alloca through codegen, first as an alloca, then as a frame index, and finally as a frame offset. llvm-svn: 247844
* [IR] Print the label operands of a catchpad like an invokeReid Kleckner2015-09-111-1/+2
| | | | | | | | | | | | | The rest of the EH pads are fine, since they have at most one label and take fewer operands for the personality. Old catchpad vs. new: %5 = catchpad [i8* bitcast (i32 ()* @"\01?filt$0@0@main@@" to i8*)] to label %__except.ret.10 unwind label %catchendblock.9 ----- %5 = catchpad [i8* bitcast (i32 ()* @"\01?filt$0@0@main@@" to i8*)] to label %__except.ret.10 unwind label %catchendblock.9 llvm-svn: 247433
* [SimplifyCFG] Use known bits to eliminate dead switch defaultsPhilip Reames2015-09-101-4/+96
| | | | | | | | | | | | This is a follow up to http://reviews.llvm.org/D11995 implementing the suggestion by Hans. If we know some of the bits of the value being switched on, we know that the maximum number of unique cases covers the unknown bits. This allows to eliminate switch defaults for large integers (i32) when most bits in the value are known. Note that I had to make the transform contingent on not having any dead cases. This is conservatively correct with the old code, but required for the new code since we might have a dead case which varies one of the known bits. Counting that towards our number of covering cases would be bad. If we do have dead cases, we'll eliminate them first, then revisit the possibly dead default. Differential Revision: http://reviews.llvm.org/D12497 llvm-svn: 247309
* Fixing bad test syntax.Andrew Kaylor2015-09-041-1/+1
| | | | llvm-svn: 246897
* [WinEH] Teach SimplfyCFG to eliminate empty cleanup pads.Andrew Kaylor2015-09-041-0/+486
| | | | | | Differential Revision: http://reviews.llvm.org/D12434 llvm-svn: 246896
* Revert r246232 and r246304.David Majnemer2015-08-281-18/+0
| | | | | | | | | This reverts isSafeToSpeculativelyExecute's use of ReadNone until we split ReadNone into two pieces: one attribute which reasons about how the function reasons about memory and another attribute which determines how it may be speculated, CSE'd, trap, etc. llvm-svn: 246331
* DI: Require subprogram definitions to be distinctDuncan P. N. Exon Smith2015-08-284-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | As a follow-up to r246098, require `DISubprogram` definitions (`isDefinition: true`) to be 'distinct'. Specifically, add an assembler check, a verifier check, and bitcode upgrading logic to combat testcase bitrot after the `DIBuilder` change. While working on the testcases, I realized that test/Linker/subprogram-linkonce-weak-odr.ll isn't relevant anymore. Its purpose was to check for a corner case in PR22792 where two subprogram definitions match exactly and share the same metadata node. The new verifier check, requiring that subprogram definitions are 'distinct', precludes that possibility. I updated almost all the IR with the following script: git grep -l -E -e '= !DISubprogram\(.* isDefinition: true' | grep -v test/Bitcode | xargs sed -i '' -e 's/= \(!DISubprogram(.*, isDefinition: true\)/= distinct \1/' Likely some variant of would work for out-of-tree testcases. llvm-svn: 246327
* [ValueTracking] readnone CallInsts are fair game for speculationDavid Majnemer2015-08-271-0/+18
| | | | | | | | | | Any call which is side effect free is trivially OK to speculate. We already had similar logic in EarlyCSE and GVN but we were missing it from isSafeToSpeculativelyExecute. This fixes PR24601. llvm-svn: 246232
* [SimplifyCFG] Prune code from a provably unreachable switch defaultPhilip Reames2015-08-261-0/+87
| | | | | | | | | | As Sanjoy pointed out over in http://reviews.llvm.org/D11819, a switch on an icmp should always be able to become a branch instruction. This patch generalizes that notion slightly to prove that the default case of a switch is unreachable if the cases completely cover all possible bit patterns in the condition. Once that's done, the switch to branch conversion kicks in just fine. Note: Duplicate case values are disallowed by the LangRef and verifier. Differential Revision: http://reviews.llvm.org/D11995 llvm-svn: 246125
* Fix a bug that caused SimplifyCFG to drop DebugLocs.Adrian Prantl2015-08-201-2/+12
| | | | | | | | | | | Instruction::dropUnknownMetadata(KnownSet) is supposed to preserve all metadata in KnownSet, but the condition for DebugLocs was inverted. Most users of dropUnknownMetadata() actually worked around this by not adding LLVMContext::MD_dbg to their list of KnowIDs. This is now made explicit. llvm-svn: 245589
* [ConstantFoldTerminator] Preserve make.implicit metadata when converting ↵Chen Li2015-08-071-0/+30
| | | | | | | | | | | | | | SwitchInst to BranchInst Summary: llvm::ConstantFoldTerminator function can convert SwitchInst with single case (and default) to a conditional BranchInst. This patch adds support to preserve make.implicit metadata on this conversion. Reviewers: sanjoy, weimingz, chenli Subscribers: mcrosier, llvm-commits Differential Revision: http://reviews.llvm.org/D11841 llvm-svn: 244348
* DI: Disallow uniquable DICompileUnitsDuncan P. N. Exon Smith2015-08-033-3/+3
| | | | | | | | | | | | | | | | | | Since r241097, `DIBuilder` has only created distinct `DICompileUnit`s. The backend is liable to start relying on that (if it hasn't already), so make uniquable `DICompileUnit`s illegal and automatically upgrade old bitcode. This is a nice cleanup, since we can remove an unnecessary `DenseSet` (and the associated uniquing info) from `LLVMContextImpl`. Almost all the testcases were updated with this script: git grep -e '= !DICompileUnit' -l -- test | grep -v test/Bitcode | xargs sed -i '' -e 's,= !DICompileUnit,= distinct !DICompileUnit,' I imagine something similar should work for out-of-tree testcases. llvm-svn: 243885
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