diff options
| -rw-r--r-- | include/llvm/Instructions.h | 5 | ||||
| -rw-r--r-- | lib/VMCore/Instructions.cpp | 12 |
2 files changed, 17 insertions, 0 deletions
diff --git a/include/llvm/Instructions.h b/include/llvm/Instructions.h index 6ee18313a2..bc4abc9797 100644 --- a/include/llvm/Instructions.h +++ b/include/llvm/Instructions.h @@ -167,6 +167,11 @@ public: : AllocationInst(Ty, ArraySize, Alloca, Align, NameStr, InsertAtEnd) {} virtual AllocaInst *clone() const; + + /// isStaticAlloca - Return true if this alloca is in the entry block of the + /// function and is a constant size. If so, the code generator will fold it + /// into the prolog/epilog code, so it is basically free. + bool isStaticAlloca() const; // Methods for support type inquiry through isa, cast, and dyn_cast: static inline bool classof(const AllocaInst *) { return true; } diff --git a/lib/VMCore/Instructions.cpp b/lib/VMCore/Instructions.cpp index 66caf5f9f0..5b271d6a31 100644 --- a/lib/VMCore/Instructions.cpp +++ b/lib/VMCore/Instructions.cpp @@ -732,6 +732,18 @@ AllocaInst::AllocaInst(const AllocaInst &AI) Instruction::Alloca, AI.getAlignment()) { } +/// isStaticAlloca - Return true if this alloca is in the entry block of the +/// function and is a constant size. If so, the code generator will fold it +/// into the prolog/epilog code, so it is basically free. +bool AllocaInst::isStaticAlloca() const { + // Must be constant size. + if (!isa<ConstantInt>(getArraySize())) return false; + + // Must be in the entry block. + const BasicBlock *Parent = getParent(); + return Parent == &Parent->getParent()->front(); +} + MallocInst::MallocInst(const MallocInst &MI) : AllocationInst(MI.getType()->getElementType(), (Value*)MI.getOperand(0), Instruction::Malloc, MI.getAlignment()) { |