Add support for __attribute__((hot)) and __attribute__((cold)).
Currently cold functions are marked with the "optsize" attribute in CodeGen
so they are always optimized for size. The hot attribute is just ignored,
LLVM doesn't have a way to express hotness at the moment.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@156723 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td
index fc886fa..0b3b3cb 100644
--- a/include/clang/Basic/Attr.td
+++ b/include/clang/Basic/Attr.td
@@ -243,6 +243,10 @@
let Args = [FunctionArgument<"FunctionDecl">];
}
+def Cold : InheritableAttr {
+ let Spellings = ["cold"];
+}
+
def Common : InheritableAttr {
let Spellings = ["common"];
}
@@ -348,6 +352,10 @@
let Spellings = ["gnu_inline"];
}
+def Hot : InheritableAttr {
+ let Spellings = ["hot"];
+}
+
def IBAction : InheritableAttr {
let Spellings = ["ibaction"];
}
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 775f500..f2dda5d 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -523,6 +523,10 @@
!F->hasFnAttr(llvm::Attribute::NoInline))
F->addFnAttr(llvm::Attribute::AlwaysInline);
+ // FIXME: Communicate hot and cold attributes to LLVM more directly.
+ if (D->hasAttr<ColdAttr>())
+ F->addFnAttr(llvm::Attribute::OptimizeForSize);
+
if (isa<CXXConstructorDecl>(D) || isa<CXXDestructorDecl>(D))
F->setUnnamedAddr(true);
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index de0e2d9..7c290f7 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -1294,6 +1294,46 @@
Str->getString()));
}
+static void handleColdAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+ // Check the attribute arguments.
+ if (!checkAttributeNumArgs(S, Attr, 0))
+ return;
+
+ if (!isa<FunctionDecl>(D)) {
+ S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+ << Attr.getName() << ExpectedFunction;
+ return;
+ }
+
+ if (D->hasAttr<HotAttr>()) {
+ S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
+ << Attr.getName() << "hot";
+ return;
+ }
+
+ D->addAttr(::new (S.Context) ColdAttr(Attr.getRange(), S.Context));
+}
+
+static void handleHotAttr(Sema &S, Decl *D, const AttributeList &Attr) {
+ // Check the attribute arguments.
+ if (!checkAttributeNumArgs(S, Attr, 0))
+ return;
+
+ if (!isa<FunctionDecl>(D)) {
+ S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+ << Attr.getName() << ExpectedFunction;
+ return;
+ }
+
+ if (D->hasAttr<ColdAttr>()) {
+ S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
+ << Attr.getName() << "cold";
+ return;
+ }
+
+ D->addAttr(::new (S.Context) HotAttr(Attr.getRange(), S.Context));
+}
+
static void handleNakedAttr(Sema &S, Decl *D, const AttributeList &Attr) {
// Check the attribute arguments.
if (!checkAttributeNumArgs(S, Attr, 0))
@@ -3825,6 +3865,8 @@
case AttributeList::AT_ownership_takes:
case AttributeList::AT_ownership_holds:
handleOwnershipAttr (S, D, Attr); break;
+ case AttributeList::AT_cold: handleColdAttr (S, D, Attr); break;
+ case AttributeList::AT_hot: handleHotAttr (S, D, Attr); break;
case AttributeList::AT_naked: handleNakedAttr (S, D, Attr); break;
case AttributeList::AT_noreturn: handleNoReturnAttr (S, D, Attr); break;
case AttributeList::AT_nothrow: handleNothrowAttr (S, D, Attr); break;
diff --git a/test/CodeGen/attr-coldhot.c b/test/CodeGen/attr-coldhot.c
new file mode 100644
index 0000000..b9bb299
--- /dev/null
+++ b/test/CodeGen/attr-coldhot.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
+
+int test1() __attribute__((__cold__)) {
+ return 42;
+
+// Check that we set the optsize attribute on the function.
+// CHECK: @test1{{.*}}optsize
+// CHECK: ret
+}
diff --git a/test/Sema/attr-coldhot.c b/test/Sema/attr-coldhot.c
new file mode 100644
index 0000000..253b189
--- /dev/null
+++ b/test/Sema/attr-coldhot.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int foo() __attribute__((__hot__));
+int bar() __attribute__((__cold__));
+
+int var1 __attribute__((__cold__)); // expected-warning{{'__cold__' attribute only applies to functions}}
+int var2 __attribute__((__hot__)); // expected-warning{{'__hot__' attribute only applies to functions}}
+
+int qux() __attribute__((__hot__)) __attribute__((__cold__)); // expected-error{{'__hot__' and cold attributes are not compatible}}
+int baz() __attribute__((__cold__)) __attribute__((__hot__)); // expected-error{{'__cold__' and hot attributes are not compatible}}