diff options
| -rw-r--r-- | include/llvm/Function.h | 6 | ||||
| -rw-r--r-- | lib/Transforms/IPO/GlobalOpt.cpp | 2 | ||||
| -rw-r--r-- | lib/Transforms/IPO/Inliner.cpp | 5 | ||||
| -rw-r--r-- | lib/Transforms/Utils/BasicInliner.cpp | 4 | ||||
| -rw-r--r-- | lib/VMCore/Function.cpp | 15 | ||||
| -rw-r--r-- | test/Transforms/GlobalOpt/deadfunction.ll | 27 |
6 files changed, 52 insertions, 7 deletions
diff --git a/include/llvm/Function.h b/include/llvm/Function.h index 678651bbf1..b5916b7572 100644 --- a/include/llvm/Function.h +++ b/include/llvm/Function.h @@ -425,6 +425,12 @@ public: /// bool hasAddressTaken(const User** = 0) const; + /// isDefTriviallyDead - Return true if it is trivially safe to remove + /// this function definition from the module (because it isn't externally + /// visible, does not have its address taken, and has no callers). To make + /// this more accurate, call removeDeadConstantUsers first. + bool isDefTriviallyDead() const; + /// callsFunctionThatReturnsTwice - Return true if the function has a call to /// setjmp or other function that gcc recognizes as "returning twice". bool callsFunctionThatReturnsTwice() const; diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index 3552d03919..c57e9fc0e8 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -1890,7 +1890,7 @@ bool GlobalOpt::OptimizeFunctions(Module &M) { if (!F->hasName() && !F->isDeclaration()) F->setLinkage(GlobalValue::InternalLinkage); F->removeDeadConstantUsers(); - if (F->use_empty() && (F->hasLocalLinkage() || F->hasLinkOnceLinkage())) { + if (F->isDefTriviallyDead()) { F->eraseFromParent(); Changed = true; ++NumFnDeleted; diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp index f00935b088..bdc9fe45d3 100644 --- a/lib/Transforms/IPO/Inliner.cpp +++ b/lib/Transforms/IPO/Inliner.cpp @@ -533,10 +533,7 @@ bool Inliner::removeDeadFunctions(CallGraph &CG, if (DNR && DNR->count(F)) continue; - if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() && - !F->hasAvailableExternallyLinkage()) - continue; - if (!F->use_empty()) + if (!F->isDefTriviallyDead()) continue; // Remove any call graph edges from the function to its callees. diff --git a/lib/Transforms/Utils/BasicInliner.cpp b/lib/Transforms/Utils/BasicInliner.cpp index 23a30cc585..50c91b6af8 100644 --- a/lib/Transforms/Utils/BasicInliner.cpp +++ b/lib/Transforms/Utils/BasicInliner.cpp @@ -131,8 +131,8 @@ void BasicInlinerImpl::inlineFunctions() { // Inline InlineFunctionInfo IFI(0, TD); if (InlineFunction(CS, IFI)) { - if (Callee->use_empty() && (Callee->hasLocalLinkage() || - Callee->hasAvailableExternallyLinkage())) + Callee->removeDeadConstantUsers(); + if (Callee->isDefTriviallyDead()) DeadFunctions.insert(Callee); Changed = true; CallSites.erase(CallSites.begin() + index); diff --git a/lib/VMCore/Function.cpp b/lib/VMCore/Function.cpp index be0f056704..bb8f62ac29 100644 --- a/lib/VMCore/Function.cpp +++ b/lib/VMCore/Function.cpp @@ -402,6 +402,7 @@ Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) { bool Function::hasAddressTaken(const User* *PutOffender) const { for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) { const User *U = *I; + // FIXME: Check for blockaddress, which does not take the address. if (!isa<CallInst>(U) && !isa<InvokeInst>(U)) return PutOffender ? (*PutOffender = U, true) : true; ImmutableCallSite CS(cast<Instruction>(U)); @@ -411,6 +412,20 @@ bool Function::hasAddressTaken(const User* *PutOffender) const { return false; } +bool Function::isDefTriviallyDead() const { + // Check the linkage + if (!hasLinkOnceLinkage() && !hasLocalLinkage() && + !hasAvailableExternallyLinkage()) + return false; + + // Check if the function is used by anything other than a blockaddress. + for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) + if (!isa<BlockAddress>(*I)) + return false; + + return true; +} + /// callsFunctionThatReturnsTwice - Return true if the function has a call to /// setjmp or other function that gcc recognizes as "returning twice". bool Function::callsFunctionThatReturnsTwice() const { diff --git a/test/Transforms/GlobalOpt/deadfunction.ll b/test/Transforms/GlobalOpt/deadfunction.ll new file mode 100644 index 0000000000..5e003c63f7 --- /dev/null +++ b/test/Transforms/GlobalOpt/deadfunction.ll @@ -0,0 +1,27 @@ +; RUN: opt < %s -globalopt -S | FileCheck %s + +; CHECK-NOT: test + +declare void @aa() +declare void @bb() + +; Test that we can erase a function which has a blockaddress referring to it +@test.x = internal unnamed_addr constant [3 x i8*] [i8* blockaddress(@test, %a), i8* blockaddress(@test, %b), i8* blockaddress(@test, %c)], align 16 +define internal void @test(i32 %n) nounwind noinline { +entry: + %idxprom = sext i32 %n to i64 + %arrayidx = getelementptr inbounds [3 x i8*]* @test.x, i64 0, i64 %idxprom + %0 = load i8** %arrayidx, align 8 + indirectbr i8* %0, [label %a, label %b, label %c] + +a: + tail call void @aa() nounwind + br label %b + +b: + tail call void @bb() nounwind + br label %c + +c: + ret void +} |