diff options
| -rw-r--r-- | llvm/lib/Transforms/IPO/Attributor.cpp | 54 | ||||
| -rw-r--r-- | llvm/test/Transforms/FunctionAttrs/noalias_returned.ll | 76 |
2 files changed, 126 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp index 064791897a5..94ed7003c96 100644 --- a/llvm/lib/Transforms/IPO/Attributor.cpp +++ b/llvm/lib/Transforms/IPO/Attributor.cpp @@ -1672,8 +1672,9 @@ struct AANoAliasFloating final : AANoAliasImpl { /// See AbstractAttribute::initialize(...). void initialize(Attributor &A) override { - // TODO: It isn't sound to initialize as the same with `AANoAliasImpl` - // because `noalias` may not be valid in the current position. + AANoAliasImpl::initialize(A); + if (isa<AllocaInst>(getAnchorValue())) + indicateOptimisticFixpoint(); } /// See AbstractAttribute::updateImpl(...). @@ -1711,8 +1712,53 @@ struct AANoAliasCallSiteArgument final : AANoAliasImpl { /// See AbstractAttribute::updateImpl(...). ChangeStatus updateImpl(Attributor &A) override { - // TODO: Implement this. - return indicatePessimisticFixpoint(); + // We can deduce "noalias" if the following conditions hold. + // (i) Associated value is assumed to be noalias in the definition. + // (ii) Associated value is assumed to be no-capture in all the uses + // possibly executed before this callsite. + // (iii) There is no other pointer argument which could alias with the + // value. + + const Value &V = getAssociatedValue(); + const IRPosition IRP = IRPosition::value(V); + + // (i) Check whether noalias holds in the definition. + + auto &NoAliasAA = A.getAAFor<AANoAlias>(*this, IRP); + + if (!NoAliasAA.isAssumedNoAlias()) + return indicatePessimisticFixpoint(); + + LLVM_DEBUG(dbgs() << "[Attributor][AANoAliasCSArg] " << V + << " is assumed NoAlias in the definition\n"); + + // (ii) Check whether the value is captured in the scope using AANoCapture. + // FIXME: This is conservative though, it is better to look at CFG and + // check only uses possibly executed before this callsite. + + auto &NoCaptureAA = A.getAAFor<AANoCapture>(*this, IRP); + if (!NoCaptureAA.isAssumedNoCaptureMaybeReturned()) + return indicatePessimisticFixpoint(); + + // (iii) Check there is no other pointer argument which could alias with the + // value. + ImmutableCallSite ICS(&getAnchorValue()); + for (unsigned i = 0; i < ICS.getNumArgOperands(); i++) { + if (getArgNo() == (int)i) + continue; + const Value *ArgOp = ICS.getArgOperand(i); + if (!ArgOp->getType()->isPointerTy()) + continue; + + // TODO: Use AliasAnalysis + // AAResults& AAR = ..; + // if(AAR.isNoAlias(&getAssociatedValue(), ArgOp)) + // return indicatePessimitisicFixpoint(); + + return indicatePessimisticFixpoint(); + } + + return ChangeStatus::UNCHANGED; } /// See AbstractAttribute::trackStatistics() diff --git a/llvm/test/Transforms/FunctionAttrs/noalias_returned.ll b/llvm/test/Transforms/FunctionAttrs/noalias_returned.ll index ccbfb3a5dfd..2f71d1e5791 100644 --- a/llvm/test/Transforms/FunctionAttrs/noalias_returned.ll +++ b/llvm/test/Transforms/FunctionAttrs/noalias_returned.ll @@ -191,3 +191,79 @@ define void @test11(i8* noalias %a) { tail call void @test11_helper(i8* %a, i8* %a) ret void } + + +; TEST 12 +; CallSite Argument +declare void @use_nocapture(i8* nocapture) +declare void @use(i8*) +define void @test12_1() { +; CHECK-LABEL: @test12_1( +; CHECK-NEXT: [[A:%.*]] = alloca i8, align 4 +; CHECK-NEXT: [[B:%.*]] = tail call noalias i8* @malloc(i64 4) +; CHECK-NEXT: tail call void @use_nocapture(i8* noalias nonnull align 4 dereferenceable(1) [[A]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* noalias nonnull align 4 dereferenceable(1) [[A]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* noalias [[B]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* noalias [[B]]) +; CHECK-NEXT: ret void +; + %A = alloca i8, align 4 + %B = tail call noalias i8* @malloc(i64 4) + tail call void @use_nocapture(i8* %A) + tail call void @use_nocapture(i8* %A) + tail call void @use_nocapture(i8* %B) + tail call void @use_nocapture(i8* %B) + ret void +} + +define void @test12_2(){ +; CHECK-LABEL: @test12_2( +; CHECK-NEXT: [[A:%.*]] = tail call noalias i8* @malloc(i64 4) +; FIXME: This should be @use_nocapture(i8* noalias [[A]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* [[A]]) +; FIXME: This should be @use_nocapture(i8* noalias [[A]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* [[A]]) +; CHECK-NEXT: tail call void @use(i8* [[A]]) +; CHECK-NEXT: tail call void @use_nocapture(i8* [[A]]) +; CHECK-NEXT: ret void +; + %A = tail call noalias i8* @malloc(i64 4) + tail call void @use_nocapture(i8* %A) + tail call void @use_nocapture(i8* %A) + tail call void @use(i8* %A) + tail call void @use_nocapture(i8* %A) + ret void +} + +declare void @two_args(i8* nocapture , i8* nocapture) +define void @test12_3(){ +; CHECK-LABEL: @test12_3( + %A = tail call noalias i8* @malloc(i64 4) +; CHECK: tail call void @two_args(i8* %A, i8* %A) + tail call void @two_args(i8* %A, i8* %A) + ret void +} + +define void @test12_4(){ +; CHECK-LABEL: @test12_4( + %A = tail call noalias i8* @malloc(i64 4) + %B = tail call noalias i8* @malloc(i64 4) + %A_0 = getelementptr i8, i8* %A, i64 0 + %A_1 = getelementptr i8, i8* %A, i64 1 + %B_0 = getelementptr i8, i8* %B, i64 0 + +; FIXME: This should be @two_args(i8* noalias %A, i8* noalias %B) +; CHECK: tail call void @two_args(i8* %A, i8* %B) + tail call void @two_args(i8* %A, i8* %B) + +; CHECK: tail call void @two_args(i8* %A, i8* %A_0) + tail call void @two_args(i8* %A, i8* %A_0) + +; CHECK: tail call void @two_args(i8* %A, i8* %A_1) + tail call void @two_args(i8* %A, i8* %A_1) + +; FIXME: This should be @two_args(i8* noalias %A_0, i8* noalias %B_0) +; CHECK: tail call void @two_args(i8* %A_0, i8* %B_0) + tail call void @two_args(i8* %A_0, i8* %B_0) + ret void +} |
