Annotate return values of allocation functions with dereferenceable_or_null
Summary:
Example
define dso_local noalias i8* @_Z6maixxnv() local_unnamed_addr #0 {
entry:
%call = tail call noalias dereferenceable_or_null(64) i8* @malloc(i64 64) #6
ret i8* %call
}
Reviewers: jdoerfert
Reviewed By: jdoerfert
Subscribers: aaron.ballman, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66651
llvm-svn: 370168
diff --git a/llvm/lib/Analysis/MemoryBuiltins.cpp b/llvm/lib/Analysis/MemoryBuiltins.cpp
index c7d2ef9..337d256 100644
--- a/llvm/lib/Analysis/MemoryBuiltins.cpp
+++ b/llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -276,6 +276,13 @@
return getAllocationDataForFunction(F, ReallocLike, TLI).hasValue();
}
+/// Tests if a value is a call or invoke to a library function that
+/// allocates memory and throws if an allocation failed (e.g., new).
+bool llvm::isOpNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
+ bool LookThroughBitCast) {
+ return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast).hasValue();
+}
+
/// extractMallocCall - Returns the corresponding CallInst if the instruction
/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
/// ignore InvokeInst here.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 1802e8c..c3be8c4 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -4178,8 +4178,41 @@
return nullptr;
}
+static void annotateAnyAllocSite(CallBase &Call, const TargetLibraryInfo *TLI) {
+ ConstantInt *Op0C = dyn_cast<ConstantInt>(Call.getOperand(0));
+ ConstantInt *Op1C = (Call.getNumArgOperands() == 1)
+ ? nullptr
+ : dyn_cast<ConstantInt>(Call.getOperand(1));
+ if ((Op0C && Op0C->isNullValue()) || (Op1C && Op1C->isNullValue()))
+ return;
+ if (isMallocLikeFn(&Call, TLI) && Op0C) {
+ Call.addAttribute(AttributeList::ReturnIndex,
+ Attribute::getWithDereferenceableOrNullBytes(
+ Call.getContext(), Op0C->getZExtValue()));
+ } else if (isOpNewLikeFn(&Call, TLI) && Op0C) {
+ Call.addAttribute(AttributeList::ReturnIndex,
+ Attribute::getWithDereferenceableBytes(
+ Call.getContext(), Op0C->getZExtValue()));
+ } else if (isReallocLikeFn(&Call, TLI) && Op1C) {
+ Call.addAttribute(AttributeList::ReturnIndex,
+ Attribute::getWithDereferenceableOrNullBytes(
+ Call.getContext(), Op1C->getZExtValue()));
+ } else if (isCallocLikeFn(&Call, TLI) && Op0C && Op1C) {
+ bool Overflow;
+ const APInt &N = Op0C->getValue();
+ APInt Size = N.umul_ov(Op1C->getValue(), Overflow);
+ if (!Overflow)
+ Call.addAttribute(AttributeList::ReturnIndex,
+ Attribute::getWithDereferenceableOrNullBytes(
+ Call.getContext(), Size.getZExtValue()));
+ }
+}
+
/// Improvements for call, callbr and invoke instructions.
Instruction *InstCombiner::visitCallBase(CallBase &Call) {
+ if (isAllocationFn(&Call, &TLI))
+ annotateAnyAllocSite(Call, &TLI);
+
if (isAllocLikeFn(&Call, &TLI))
return visitAllocSite(Call);