diff options
| -rw-r--r-- | lib/Transforms/IPO/GlobalOpt.cpp | 24 | ||||
| -rw-r--r-- | test/Transforms/GlobalOpt/memset-null.ll | 19 |
2 files changed, 38 insertions, 5 deletions
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp index 9d98bb156b..371500bc78 100644 --- a/lib/Transforms/IPO/GlobalOpt.cpp +++ b/lib/Transforms/IPO/GlobalOpt.cpp @@ -241,15 +241,15 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS, GS.HasPHIUser = true; } else if (isa<CmpInst>(I)) { GS.isCompared = true; - } else if (isa<MemTransferInst>(I)) { - const MemTransferInst *MTI = cast<MemTransferInst>(I); + } else if (const MemTransferInst *MTI = dyn_cast<MemTransferInst>(I)) { + if (MTI->isVolatile()) return true; if (MTI->getArgOperand(0) == V) GS.StoredType = GlobalStatus::isStored; if (MTI->getArgOperand(1) == V) GS.isLoaded = true; - } else if (isa<MemSetInst>(I)) { - assert(cast<MemSetInst>(I)->getArgOperand(0) == V && - "Memset only takes one pointer!"); + } else if (const MemSetInst *MSI = dyn_cast<MemSetInst>(I)) { + assert(MSI->getArgOperand(0) == V && "Memset only takes one pointer!"); + if (MSI->isVolatile()) return true; GS.StoredType = GlobalStatus::isStored; } else { return true; // Any other non-load instruction might take address! @@ -2438,6 +2438,20 @@ static bool EvaluateFunction(Function *F, Constant *&RetVal, // Cannot handle inline asm. if (isa<InlineAsm>(CI->getCalledValue())) return false; + if (MemSetInst *MSI = dyn_cast<MemSetInst>(CI)) { + if (MSI->isVolatile()) return false; + Constant *Ptr = getVal(Values, MSI->getDest()); + Constant *Val = getVal(Values, MSI->getValue()); + Constant *DestVal = ComputeLoadResult(getVal(Values, Ptr), + MutatedMemory); + if (Val->isNullValue() && DestVal->isNullValue()) { + // This memset is a no-op. + ++CurInst; + continue; + } + return false; + } + // Resolve function pointers. Function *Callee = dyn_cast<Function>(getVal(Values, CI->getCalledValue())); diff --git a/test/Transforms/GlobalOpt/memset-null.ll b/test/Transforms/GlobalOpt/memset-null.ll new file mode 100644 index 0000000000..7a24a2a22b --- /dev/null +++ b/test/Transforms/GlobalOpt/memset-null.ll @@ -0,0 +1,19 @@ +; RUN: opt -globalopt %s -S -o - | FileCheck %s +; PR10047 + + +%0 = type { i32, void ()* } +%struct.A = type { [100 x i32] } + +; CHECK: @a +@a = global %struct.A zeroinitializer, align 4 +@llvm.global_ctors = appending global [1 x %0] [%0 { i32 65535, void ()* @_GLOBAL__I_a }] + +declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind + +; CHECK-NOT: GLOBAL__I_a +define internal void @_GLOBAL__I_a() nounwind { +entry: + tail call void @llvm.memset.p0i8.i64(i8* bitcast (%struct.A* @a to i8*), i8 0, i64 400, i32 4, i1 false) nounwind + ret void +} |