================
@@ -0,0 +1,268 @@
+//===- UnsafeBufferUsageExtractor.cpp
-------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM
Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include
"clang/Analysis/Scalable/Analyses/UnsafeBufferUsage/UnsafeBufferUsageExtractor.h"
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DynamicRecursiveASTVisitor.h"
+#include "clang/AST/StmtVisitor.h"
+#include "clang/Analysis/Analyses/UnsafeBufferUsage.h"
+#include "clang/Analysis/Scalable/ASTEntityMapping.h"
+#include
"clang/Analysis/Scalable/Analyses/UnsafeBufferUsage/UnsafeBufferUsage.h"
+#include
"clang/Analysis/Scalable/Analyses/UnsafeBufferUsage/UnsafeBufferUsageBuilder.h"
+#include "clang/Analysis/Scalable/Model/EntityId.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/Error.h"
+#include <memory>
+
+namespace {
+using namespace clang;
+using namespace ssaf;
+
+static bool hasPointerType(const Expr *E) {
+ auto Ty = E->getType();
+ return !Ty.isNull() && !Ty->isFunctionPointerType() &&
+ (Ty->isPointerType() || Ty->isArrayType());
+}
+
+constexpr inline auto buildEntityPointerLevel =
+ UnsafeBufferUsageTUSummaryBuilder::buildEntityPointerLevel;
+
+// Translate a pointer type expression 'E' to a (set of) EntityPointerLevel(s)
+// associated with the declared type of the base address of `E`.
+//
+// The translation is a process of stripping off the pointer 'E' until its base
+// address can be represented by an entity, with the number of dereferences
+// tracked by incrementing the pointer level. Naturally, taking address of, as
+// the inverse operation of dereference, is tracked by decrementing the pointer
+// level.
+//
+// For example, suppose there are pointers and arrays declared as
+// int *ptr, **p1, **p2;
+// int arr[10][10];
+// , the translation of expressions involving these base addresses will be:
+// Translate(ptr + 5) -> {(ptr, 1)}
+// Translate(arr[5]) -> {(arr, 2)}
+// Translate(cond ? p1[5] : p2) -> {(p1, 2), (p2, 1)}
+// Translate(&arr[5]) -> {(arr, 1)}
+class EntityPointerLevelTranslator
+ : ConstStmtVisitor<EntityPointerLevelTranslator,
+ Expected<EntityPointerLevelSet>> {
+ friend class StmtVisitorBase;
+
+ // Fallback method for all unsupported expression kind:
+ llvm::Error fallback(const Stmt *E) {
+ return llvm::createStringError(
+ "unsupported expression kind for translation to "
+ "EntityPointerLevel: %s",
+ E->getStmtClassName());
+ }
+
+ UnsafeBufferUsageTUSummaryBuilder &Builder;
+
+ static EntityPointerLevel incrementPointerLevel(const EntityPointerLevel &E)
{
+ return buildEntityPointerLevel(E.getEntity(), E.getPointerLevel() + 1);
+ }
+
+ static EntityPointerLevel decrementPointerLevel(const EntityPointerLevel &E)
{
+ assert(E.getPointerLevel() > 0);
+ return buildEntityPointerLevel(E.getEntity(), E.getPointerLevel() - 1);
+ }
+
+ EntityPointerLevel createEntityPointerLevelFor(const EntityName &Name) {
+ return buildEntityPointerLevel(Builder.addEntity(Name), 1);
+ }
+
+ // The common helper function for Translate(*base):
+ // Translate(*base) -> Translate(base) with .pointerLevel + 1
+ Expected<EntityPointerLevelSet> translateDereferencePointer(const Expr *Ptr)
{
+ assert(hasPointerType(Ptr));
+
+ Expected<EntityPointerLevelSet> SubResult = Visit(Ptr);
+ if (!SubResult)
+ return SubResult.takeError();
+
+ auto Incremented = llvm::map_range(*SubResult, incrementPointerLevel);
+ return EntityPointerLevelSet{Incremented.begin(), Incremented.end()};
+ }
+
+public:
+ EntityPointerLevelTranslator(UnsafeBufferUsageTUSummaryBuilder &Builder)
+ : Builder(Builder) {}
+
+ Expected<EntityPointerLevelSet> translate(const Expr *E) { return Visit(E); }
+
+private:
+ Expected<EntityPointerLevelSet> VisitStmt(const Stmt *E) {
+ return fallback(E);
+ }
+
+ // Translate(base + x) -> Translate(base)
+ // Translate(x + base) -> Translate(base)
+ // Translate(base - x) -> Translate(base)
+ // Translate(base {+=, -=, =} x) -> Translate(base)
+ // Translate(x, base) -> Translate(base)
+ Expected<EntityPointerLevelSet> VisitBinaryOperator(const BinaryOperator *E)
{
+ switch (E->getOpcode()) {
+ case clang::BO_Add:
+ if (hasPointerType(E->getLHS()))
+ return Visit(E->getLHS());
+ return Visit(E->getRHS());
+ case clang::BO_Sub:
+ case clang::BO_AddAssign:
+ case clang::BO_SubAssign:
+ case clang::BO_Assign:
+ return Visit(E->getLHS());
+ case clang::BO_Comma:
+ return Visit(E->getRHS());
----------------
ziqingluo-90 wrote:
No need.
Suppose in the program we have
```
void f(int *p1, int *p2) {
(p1 + 5, p2)[5];
}
```
The API of `-Wunsafe-buffer-usage` returns 2 unsafe pointers: `p1` and `(p1 +
5, p2)`.
For `(p1 + 5, p2)`, we are only interested in the base address provided from
`p2`.
https://github.com/llvm/llvm-project/pull/182941
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