Add __builtin_assume and __builtin_assume_aligned using @llvm.assume.
This makes use of the recently-added @llvm.assume intrinsic to implement a
__builtin_assume(bool) intrinsic (to provide additional information to the
optimizer). This hooks up __assume in MS-compatibility mode to mirror
__builtin_assume (the semantics have been intentionally kept compatible), and
implements GCC's __builtin_assume_aligned as assume((p - o) & mask == 0). LLVM
now contains special logic to deal with assumptions of this form.
llvm-svn: 217349
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 87042d1..435b951 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -189,9 +189,14 @@
return ExprError();
break;
case Builtin::BI__assume:
+ case Builtin::BI__builtin_assume:
if (SemaBuiltinAssume(TheCall))
return ExprError();
break;
+ case Builtin::BI__builtin_assume_aligned:
+ if (SemaBuiltinAssumeAligned(TheCall))
+ return ExprError();
+ break;
case Builtin::BI__builtin_object_size:
if (SemaBuiltinConstantArgRange(TheCall, 1, 0, 3))
return ExprError();
@@ -2059,7 +2064,46 @@
if (Arg->HasSideEffects(Context))
return Diag(Arg->getLocStart(), diag::warn_assume_side_effects)
- << Arg->getSourceRange();
+ << Arg->getSourceRange()
+ << cast<FunctionDecl>(TheCall->getCalleeDecl())->getIdentifier();
+
+ return false;
+}
+
+/// Handle __builtin_assume_aligned. This is declared
+/// as (const void*, size_t, ...) and can take one optional constant int arg.
+bool Sema::SemaBuiltinAssumeAligned(CallExpr *TheCall) {
+ unsigned NumArgs = TheCall->getNumArgs();
+
+ if (NumArgs > 3)
+ return Diag(TheCall->getLocEnd(),
+ diag::err_typecheck_call_too_many_args_at_most)
+ << 0 /*function call*/ << 3 << NumArgs
+ << TheCall->getSourceRange();
+
+ // The alignment must be a constant integer.
+ Expr *Arg = TheCall->getArg(1);
+
+ // We can't check the value of a dependent argument.
+ if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
+ llvm::APSInt Result;
+ if (SemaBuiltinConstantArg(TheCall, 1, Result))
+ return true;
+
+ if (!Result.isPowerOf2())
+ return Diag(TheCall->getLocStart(),
+ diag::err_alignment_not_power_of_two)
+ << Arg->getSourceRange();
+ }
+
+ if (NumArgs > 2) {
+ ExprResult Arg(TheCall->getArg(2));
+ InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
+ Context.getSizeType(), false);
+ Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
+ if (Arg.isInvalid()) return true;
+ TheCall->setArg(2, Arg.get());
+ }
return false;
}