Mordante created this revision.
Mordante added reviewers: rsmith, rjmccall, aaron.ballman.
Mordante added a project: clang.
Herald added a subscriber: cfe-commits.
Mordante requested review of this revision.
Allows the likelihood attributes on label, which are not part of a case
statement. When a `goto` is used it accepts the attribute placed on the target
label.
Depends on D85091 <https://reviews.llvm.org/D85091>.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D86559
Files:
clang/lib/CodeGen/CGStmt.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/CodeGenCXX/attr-likelihood-if-branch-weights.cpp
clang/test/Sema/attr-likelihood.c
clang/test/SemaCXX/attr-likelihood.cpp
Index: clang/test/SemaCXX/attr-likelihood.cpp
===================================================================
--- clang/test/SemaCXX/attr-likelihood.cpp
+++ clang/test/SemaCXX/attr-likelihood.cpp
@@ -115,8 +115,7 @@
if (x)
goto lbl;
- // FIXME: allow the attribute on the label
- [[unlikely]] lbl : // expected-error {{'unlikely' attribute cannot be applied to a declaration}}
+ [[likely]] lbl :
[[likely]] x = x + 1;
[[likely]]++ x;
Index: clang/test/Sema/attr-likelihood.c
===================================================================
--- clang/test/Sema/attr-likelihood.c
+++ clang/test/Sema/attr-likelihood.c
@@ -43,8 +43,7 @@
if (x)
goto lbl;
- // FIXME: allow the attribute on the label
- [[clang::unlikely]] lbl : // expected-error {{'unlikely' attribute cannot be applied to a declaration}}
+ [[clang::unlikely]] lbl :
[[clang::likely]] x = x + 1;
[[clang::likely]]++ x;
Index: clang/test/CodeGenCXX/attr-likelihood-if-branch-weights.cpp
===================================================================
--- clang/test/CodeGenCXX/attr-likelihood-if-branch-weights.cpp
+++ clang/test/CodeGenCXX/attr-likelihood-if-branch-weights.cpp
@@ -125,7 +125,45 @@
// Make sure the branches aren't optimized away.
b = true;
}
+
+ // CHECK: br {{.*}} !prof !8
+ if (b) {
+ goto uend;
+ } else {
+ // Make sure the branches aren't optimized away.
+ b = true;
+ }
+
+ // CHECK: br {{.*}} !prof !7
+ if (b) {
+ goto lend;
+ } else {
+ // Make sure the branches aren't optimized away.
+ b = true;
+ }
+
+ // CHECK: br {{.*}} !prof !8
+ if (b) {
+ goto ugcc;
+ } else {
+ // Make sure the branches aren't optimized away.
+ b = true;
+ }
+
+ // CHECK: br {{.*}} !prof !7
+ if (b) {
+ goto lgcc;
+ } else {
+ // Make sure the branches aren't optimized away.
+ b = true;
+ }
end:;
+[[unlikely]] uend:;
+[[likely]] lend:;
+// GCC attributes are handled in a special way, make sure the likelihood
+// attributes aren't ignored.
+[[unlikely]] ugcc: __attribute__((unused));;
+[[likely]] lgcc: __attribute__((unused));;
}
void ReturnStmt() {
Index: clang/lib/Sema/SemaDeclAttr.cpp
===================================================================
--- clang/lib/Sema/SemaDeclAttr.cpp
+++ clang/lib/Sema/SemaDeclAttr.cpp
@@ -6410,6 +6410,29 @@
D->addAttr(::new (S.Context) DeprecatedAttr(S.Context, AL, Str, Replacement));
}
+static bool validateLikelihoodAttr(Sema &S, Decl *D, const ParsedAttr &A) {
+ if (!isa<LabelDecl>(D)) {
+ S.Diag(A.getRange().getBegin(), diag::err_stmt_attribute_invalid_on_decl)
+ << A << D->getBeginLoc();
+ return false;
+ }
+
+ if (!S.getLangOpts().CPlusPlus20 && A.isCXX11Attribute() && !A.getScopeName())
+ S.Diag(A.getLoc(), diag::ext_cxx20_attr) << A << A.getRange();
+
+ return true;
+}
+
+static void handleLikelyAttr(Sema &S, Decl *D, const ParsedAttr &A) {
+ if (validateLikelihoodAttr(S, D, A))
+ D->addAttr(::new (S.Context) LikelyAttr(S.Context, A));
+}
+
+static void handleUnlikelyAttr(Sema &S, Decl *D, const ParsedAttr &A) {
+ if (validateLikelihoodAttr(S, D, A))
+ D->addAttr(::new (S.Context) UnlikelyAttr(S.Context, A));
+}
+
static bool isGlobalVar(const Decl *D) {
if (const auto *S = dyn_cast<VarDecl>(D))
return S->hasGlobalStorage();
@@ -6943,6 +6966,12 @@
case ParsedAttr::AT_Deprecated:
handleDeprecatedAttr(S, D, AL);
break;
+ case ParsedAttr::AT_Likely:
+ handleLikelyAttr(S, D, AL);
+ break;
+ case ParsedAttr::AT_Unlikely:
+ handleUnlikelyAttr(S, D, AL);
+ break;
case ParsedAttr::AT_Destructor:
if (S.Context.getTargetInfo().getTriple().isOSAIX())
llvm::report_fatal_error("'destructor' attribute is not yet supported on AIX");
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -672,17 +672,8 @@
LikelihoodAttributeFinder(const Stmt *S) { Visit(S); }
void VisitAttributedStmt(const AttributedStmt *S) {
- for (const auto *A : S->getAttrs()) {
- if (isa<LikelyAttr>(A)) {
- Result = Likely;
- return;
- }
- if (isa<UnlikelyAttr>(A)) {
- Result = Unlikely;
- return;
- }
- }
- Visit(S->getSubStmt());
+ if (!ProcessLikelihoodAttribute(S->getAttrs()))
+ Visit(S->getSubStmt());
}
void VisitCompoundStmt(const CompoundStmt *CS) {
@@ -692,8 +683,28 @@
return;
}
}
+ void VisitGotoStmt(const GotoStmt *GS) {
+ // Decl::getAttrs requires Decl::hasAttrs() == true.
+ const LabelDecl *LD = GS->getLabel();
+ if (LD->hasAttrs())
+ ProcessLikelihoodAttribute(LD->getAttrs());
+ }
void VisitStmt(const Stmt *) {}
+
+ bool ProcessLikelihoodAttribute(const ArrayRef<const clang::Attr *> &Attrs) {
+ for (const auto *A : Attrs) {
+ if (isa<LikelyAttr>(A)) {
+ Result = Likely;
+ return true;
+ }
+ if (isa<UnlikelyAttr>(A)) {
+ Result = Unlikely;
+ return true;
+ }
+ }
+ return false;
+ }
};
} // end anonymous namespace
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