aaron.ballman added inline comments.
================
Comment at: include/clang/Basic/Attr.td:894
@@ -893,1 +893,3 @@
+def DisableTailCalls : InheritableAttr {
+ let Spellings = [GNU<"disable_tail_calls">];
----------------
We already have an attribute that is tangentially related: OptimizeNone. Would
it make sense to have that attribute take arguments that control what
optimizations are enabled/disabled? How should these two attributes (and the
resulting functionality) interact? For instance, if I specify optnone on a
function, should that also disable tail call optimizations by creating an
implicit instance of this new attribute?
================
Comment at: include/clang/Basic/Attr.td:895
@@ +894,3 @@
+def DisableTailCalls : InheritableAttr {
+ let Spellings = [GNU<"disable_tail_calls">];
+ let Subjects = SubjectList<[Function]>;
----------------
Do we also want a C++ spelling for this attribute, under the clang namespace?
================
Comment at: include/clang/Basic/Attr.td:896
@@ +895,3 @@
+ let Spellings = [GNU<"disable_tail_calls">];
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [Undocumented];
----------------
Should this also apply to Objective-C methods?
================
Comment at: include/clang/Basic/Attr.td:897
@@ +896,3 @@
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [Undocumented];
+}
----------------
Please document this attribute.
================
Comment at: lib/CodeGen/CGCall.cpp:1477
@@ -1476,3 +1476,3 @@
- FuncAttrs.addAttribute("disable-tail-calls",
- llvm::toStringRef(CodeGenOpts.DisableTailCalls));
+ if ((TargetDecl && TargetDecl->hasAttr<DisableTailCallsAttr>()) ||
+ CodeGenOpts.DisableTailCalls)
----------------
Better to move this into the block that already tests TargetDecl (around line
1403 or so).
================
Comment at: lib/CodeGen/CGCall.cpp:1480
@@ +1479,3 @@
+ FuncAttrs.addAttribute("disable-tail-calls", "true");
+ else
+ FuncAttrs.addAttribute("disable-tail-calls", "false");
----------------
Can do this in a single line with ?:
================
Comment at: lib/Sema/SemaDeclAttr.cpp:4882
@@ +4881,3 @@
+ case AttributeList::AT_DisableTailCalls:
+ handleSimpleAttribute<DisableTailCallsAttr>(S, D, Attr);
+ break;
----------------
Are there semantic checks we would like to perform on the declaration for
nonsense uses of this attribute, such as functions marked [[noreturn]], etc?
http://reviews.llvm.org/D12547
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