SimplifyLibCalls: Optimize wcslen

Refactor the strlen optimization code to work for both strlen and wcslen.

This especially helps with programs in the wild where people pass
L"string"s to const std::wstring& function parameters and the wstring
constructor gets inlined.

This also fixes a lingerind API problem/bug in getConstantStringInfo()
where zeroinitializers would always give you an empty string (without a
length) back regardless of the actual length of the initializer which
did not work well in the TrimAtNul==false causing the PR mentioned
below.

Note that the fixed getConstantStringInfo() needed fixes to SelectionDAG
memcpy lowering and may lead to some cases for out-of-bounds
zeroinitializer accesses not getting optimized anymore. So some code
with UB may produce out of bound memory reads now instead of just
producing zeros.

The refactoring "accidentally" fixes http://llvm.org/PR32124

Differential Revision: https://reviews.llvm.org/D32839

llvm-svn: 303461

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index f0b9dfb2d62..8b0ff66334a 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -2616,8 +2616,8 @@ Constant *ConstantDataSequential::getElementAsConstant(unsigned Elt) const {
   return ConstantInt::get(getElementType(), getElementAsInteger(Elt));
 }
 
-bool ConstantDataSequential::isString() const {
-  return isa<ArrayType>(getType()) && getElementType()->isIntegerTy(8);
+bool ConstantDataSequential::isString(unsigned CharSize) const {
+  return isa<ArrayType>(getType()) && getElementType()->isIntegerTy(CharSize);
 }
 
 bool ConstantDataSequential::isCString() const {