rsmith added inline comments.
================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:2829-2830
+def err_musttail_needs_call : Error<
+ "%0 attribute requires that the return value is a function call, which must "
+ "not create or destroy any temporaries.">;
+def err_musttail_only_from_function : Error<
----------------
aaron.ballman wrote:
>
Can we diagnose these two cases separately?
================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:2833-2835
+def err_musttail_return_type_mismatch : Error<
+ "%0 attribute requires that caller and callee have identical parameter types
"
+ "and return types">;
----------------
It would be useful to say what didn't match. Eg, parameter index or parameter
name.
================
Comment at: clang/include/clang/Basic/DiagnosticSemaKinds.td:2837
+def err_musttail_no_destruction : Error<
+ "%0 attribute does not allow any variables in scope that require destruction"
+ >;
----------------
aaron.ballman wrote:
> All automatic variables require destruction when leaving the scope, so this
> diagnostic reads oddly to me. Perhaps you mean that the variables must all be
> trivially destructible?
Can we say which variable? I think it'd be useful to have both a diagnostic and
a note here, pointing to the attribute and variable.
================
Comment at: clang/lib/CodeGen/CGCall.cpp:5313
+ // If this is a musttail call, return immediately. We do not branch to the
+ // prologue in this case.
+ if (InMustTailCallExpr) {
----------------
epilogue?
================
Comment at: clang/lib/Sema/JumpDiagnostics.cpp:35
+/// cleanups properly. Indirect jumps and ASM jumps can't do cleanups because
+/// the target is unknown. Return statements with \c [musttail] cannot handle
+/// any cleanups due to the nature of a tail call.
----------------
================
Comment at: clang/lib/Sema/SemaStmtAttr.cpp:15
#include "clang/AST/EvaluatedExprVisitor.h"
+#include "clang/AST/ParentMapContext.h"
#include "clang/Basic/SourceManager.h"
----------------
Looks like you're not using this. (And that's good: the parent map should never
be used in the static compiler; it's a tooling-only facility.)
================
Comment at: clang/test/CodeGen/attr-musttail.cpp:8
+ if (x) {
+ [[clang::musttail]] return Bar(x); // CHECK: %call = musttail call i32
@_Z3Bari(i32 %1)
+ } else {
----------------
I'd like to see a `CHECK-NEXT: ret i32 %call` here too.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D99517/new/
https://reviews.llvm.org/D99517
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