[cfe-commits] [PATCH] Invariants (and Assume Aligned) - Clang

[Dmitri Gribenko]

  Please update docs/LanguageExtensions.html with descriptions of these two new builtins.


================
Comment at: lib/Sema/SemaChecking.cpp:1605
@@ +1604,3 @@
+  // We can't check the value of a dependent argument.
+  if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
+    llvm::APSInt Result;
----------------
Should we just reject these cases?  Seems like we would silently accept it without checking.

Or would it get checked during template instantiation?

================
Comment at: test/Sema/builtin-assume-aligned.c:37
@@ +36,2 @@
+}
+
----------------
Still not enough :)

Please add:
  __builtin_assume_aligned(a, 1ULL << 63);
  int test9(int *a, int z) {
    a = __builtin_assume_aligned(a, z + 1); // not a constant expression
    return a[0];
  }
  template<int z>
  int test10(int *a) {
    a = __builtin_assume_aligned(a, z + 1); // value-dependent
    return a[0];
  }
  void test10_inst(int *a) {
    test10<32>(a); // power of 2
    test10<42>(a); // not a power of 2
  }
  template<typename T>
  int test11(int *a, T z) {
    a = __builtin_assume_aligned(a, z + 1); // value-dependent
    return a[0];
  }
  void test11_inst(int *a) {
    test11(a, 42);
  }
  int test12(int *a) {
    a = __builtin_assume_aligned(a, 32, "abc"); // wrong type
    return a[0];
  }
  int test13(int *a, int z) {
    a = __builtin_assume_aligned(a, z); // not a constant
    return a[0];
  }

================
Comment at: lib/Sema/SemaChecking.cpp:1610-1613
@@ +1609,6 @@
+
+    if (Result.getLimitedValue() > +llvm::Value::MaximumAlignment ||
+        !Result.isUnsigned())
+      return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
+           << "0" << +llvm::Value::MaximumAlignment << Arg->getSourceRange();
+    if (!Result.isPowerOf2())
----------------
What is the purpose of the '+' in '+llvm::Value::MaximumAlignment'?


http://llvm-reviews.chandlerc.com/D149