Instcombine should turn llvm.objectsize of a alloca with static size to an integer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97827 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 88d8abd..a241f16 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -304,29 +304,39 @@
switch (II->getIntrinsicID()) {
default: break;
case Intrinsic::objectsize: {
- const Type *ReturnTy = CI.getType();
- Value *Op1 = II->getOperand(1);
- bool Min = (cast<ConstantInt>(II->getOperand(2))->getZExtValue() == 1);
-
// We need target data for just about everything so depend on it.
if (!TD) break;
+ const Type *ReturnTy = CI.getType();
+ bool Min = (cast<ConstantInt>(II->getOperand(2))->getZExtValue() == 1);
+
// Get to the real allocated thing and offset as fast as possible.
- Op1 = Op1->stripPointerCasts();
+ Value *Op1 = II->getOperand(1)->stripPointerCasts();
// If we've stripped down to a single global variable that we
// can know the size of then just return that.
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op1)) {
if (GV->hasDefinitiveInitializer()) {
Constant *C = GV->getInitializer();
- uint64_t globalSize = TD->getTypeAllocSize(C->getType());
- return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, globalSize));
+ uint64_t GlobalSize = TD->getTypeAllocSize(C->getType());
+ return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, GlobalSize));
} else {
+ // Can't determine size of the GV.
Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
return ReplaceInstUsesWith(CI, RetVal);
}
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) {
-
+ } else if (AllocaInst *AI = dyn_cast<AllocaInst>(Op1)) {
+ // Get alloca size.
+ if (AI->getAllocatedType()->isSized()) {
+ uint64_t AllocaSize = TD->getTypeAllocSize(AI->getAllocatedType());
+ if (AI->isArrayAllocation()) {
+ const ConstantInt *C = dyn_cast<ConstantInt>(AI->getArraySize());
+ if (!C) break;
+ AllocaSize *= C->getZExtValue();
+ }
+ return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, AllocaSize));
+ }
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) {
// Only handle constant GEPs here.
if (CE->getOpcode() != Instruction::GetElementPtr) break;
GEPOperator *GEP = cast<GEPOperator>(CE);
@@ -361,6 +371,9 @@
return ReplaceInstUsesWith(CI, RetVal);
}
+
+ // Do not return "I don't know" here. Later optimization passes could
+ // make it possible to evaluate objectsize to a constant.
break;
}
case Intrinsic::bswap: