[clang] added allocsize attribute to allocation functions

clang/lib/Sema/SemaDecl.cpp

@@ -15340,6 +15340,26 @@ void Sema::AddKnownFunctionAttributes(FunctionDecl *FD) {
     default:
       break;
     }
+
+    // Add allocsize attribute for allocation functions.
+    switch (BuiltinID) {
+    case Builtin::BIcalloc:
+      FD->addAttr(AllocSizeAttr::CreateImplicit(
+          Context, ParamIdx(1, FD), ParamIdx(2, FD), FD->getLocation()));
+      break;
+    case Builtin::BImemalign:
+    case Builtin::BIaligned_alloc:
+    case Builtin::BIrealloc:
+      FD->addAttr(AllocSizeAttr::CreateImplicit(Context, ParamIdx(2, FD),
+                                                ParamIdx(), FD->getLocation()));
+      break;
+    case Builtin::BImalloc:
+      FD->addAttr(AllocSizeAttr::CreateImplicit(Context, ParamIdx(1, FD),
+                                                ParamIdx(), FD->getLocation()));
+      break;
+    default:
+      break;
+    }
   }
 
   AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(FD);

clang/test/CodeGen/allocs-fns-allocsize.c

@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm < %s | FileCheck %s
+
+typedef __SIZE_TYPE__ size_t;
+
+void *malloc(size_t);
+void *calloc(size_t, size_t);
+void *realloc(void *, size_t);
+void *aligned_alloc(size_t, size_t);
+void *memalign(size_t, size_t);
+
+void *malloc_test(size_t n) {
+  return malloc(n);
+}
+
+void *calloc_test(size_t e, size_t n) {
+  return calloc(e, n);
+}
+
+void *realloc_test(void *p, size_t n) {
+  return realloc(p, n);
+}
+
+void *aligned_alloc_test(size_t n, size_t a) {
+  return aligned_alloc(a, n);
+}
+
+void *memalign_test(size_t n, size_t a) {
+  return memalign(a, n);
+}
+
+// CHECK: @malloc(i64 noundef) #1
+// CHECK: @calloc(i64 noundef, i64 noundef) #2
+// CHECK: @realloc(i8* noundef, i64 noundef) #3
+// CHECK: @aligned_alloc(i64 noundef, i64 noundef) #3
+// CHECK: @memalign(i64 noundef, i64 noundef) #3
+
+// CHECK: attributes #1 = { allocsize(0)
+// CHECK: attributes #2 = { allocsize(0,1)
+// CHECK: attributes #3 = { allocsize(1)