[PATCH] D30884: When diagnosing taking address of packed members skip __unaligned-qualified expressions

Roger Ferrer Ibanez via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Mon Mar 13 03:39:44 PDT 2017


rogfer01 created this revision.

Given that we have already explicitly stated in the qualifier that the expression is `__unaligned`,
it makes little sense to diagnose that the address of the packed member may not be aligned.


https://reviews.llvm.org/D30884

Files:
  lib/Sema/SemaChecking.cpp
  test/Sema/address-unaligned.c


Index: test/Sema/address-unaligned.c
===================================================================
--- /dev/null
+++ test/Sema/address-unaligned.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -fsyntax-only -fms-extensions -verify %s
+// expected-no-diagnostics
+
+typedef
+struct __attribute__((packed)) S1 {
+  char c0;
+  int x;
+  char c1;
+} S1;
+
+void bar(__unaligned int *);
+
+void foo(__unaligned S1* s1)
+{
+    bar(&s1->x);
+}
Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -11851,6 +11851,10 @@
   if (!ME)
     return;
 
+  // No need to check expressions with an __unaligned-qualified type.
+  if (E->getType().getQualifiers().hasUnaligned())
+    return;
+
   // For a chain of MemberExpr like "a.b.c.d" this list
   // will keep FieldDecl's like [d, c, b].
   SmallVector<FieldDecl *, 4> ReverseMemberChain;


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