[llvm] 7c0e3a7 - [clang][IR] Add support for leaf attribute
Haowei Wu via llvm-commits
llvm-commits at lists.llvm.org
Mon Dec 14 14:48:36 PST 2020
Author: Gulfem Savrun Yeniceri
Date: 2020-12-14T14:48:17-08:00
New Revision: 7c0e3a77bc43a9c4d05f68ffd4e84d0f75efbd91
URL: https://github.com/llvm/llvm-project/commit/7c0e3a77bc43a9c4d05f68ffd4e84d0f75efbd91
DIFF: https://github.com/llvm/llvm-project/commit/7c0e3a77bc43a9c4d05f68ffd4e84d0f75efbd91.diff
LOG: [clang][IR] Add support for leaf attribute
This patch adds support for leaf attribute as an optimization hint
in Clang/LLVM.
Differential Revision: https://reviews.llvm.org/D90275
Added:
clang/test/CodeGen/attr-leaf.c
clang/test/Sema/attr-leaf.c
Modified:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/lib/CodeGen/CGCall.cpp
clang/lib/Sema/SemaDeclAttr.cpp
clang/test/Misc/pragma-attribute-supported-attributes-list.test
llvm/include/llvm/Bitcode/LLVMBitCodes.h
llvm/include/llvm/IR/Attributes.td
llvm/lib/AsmParser/LLLexer.cpp
llvm/lib/AsmParser/LLParser.cpp
llvm/lib/AsmParser/LLToken.h
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
llvm/lib/IR/Attributes.cpp
llvm/lib/IR/Verifier.cpp
llvm/lib/Transforms/Utils/CodeExtractor.cpp
llvm/test/Bitcode/attributes.ll
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 79902c8f5b89..61eb86ac81a1 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1448,6 +1448,13 @@ def LayoutVersion : InheritableAttr, TargetSpecificAttr<TargetMicrosoftCXXABI> {
let Documentation = [LayoutVersionDocs];
}
+def Leaf : InheritableAttr {
+ let Spellings = [GCC<"leaf">];
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [LeafDocs];
+ let SimpleHandler = 1;
+}
+
def LifetimeBound : DeclOrTypeAttr {
let Spellings = [Clang<"lifetimebound", 0>];
let Subjects = SubjectList<[ParmVar, ImplicitObjectParameter], ErrorDiag>;
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 28f35cf2c0c7..e70596b5ac28 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -3976,6 +3976,22 @@ are used to instantiate the specialization.
}];
}
+def LeafDocs : Documentation {
+ let Category = DocCatVariable;
+ let Content = [{
+
+The ``leaf`` attribute is used as a compiler hint to improve dataflow analysis
+in library functions. Functions marked with the ``leaf`` attribute are not allowed
+to jump back into the caller's translation unit, whether through invoking a
+callback function, an external function call, use of ``longjmp``, or other means.
+Therefore, they cannot use or modify any data that does not escape the caller function's
+compilation unit.
+
+For more information see
+`gcc documentation <https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html>`
+}];
+}
+
def NoStackProtectorDocs : Documentation {
let Category = DocCatFunction;
let Content = [{
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 5db34b693bf3..73194be922dd 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1989,6 +1989,8 @@ void CodeGenModule::ConstructAttributeList(
FuncAttrs.addAttribute("no_caller_saved_registers");
if (TargetDecl->hasAttr<AnyX86NoCfCheckAttr>())
FuncAttrs.addAttribute(llvm::Attribute::NoCfCheck);
+ if (TargetDecl->hasAttr<LeafAttr>())
+ FuncAttrs.addAttribute(llvm::Attribute::NoCallback);
HasOptnone = TargetDecl->hasAttr<OptimizeNoneAttr>();
if (auto *AllocSize = TargetDecl->getAttr<AllocSizeAttr>()) {
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 15094854300d..395d0ef57945 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -7715,6 +7715,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
case ParsedAttr::AT_AnyX86NoCfCheck:
handleNoCfCheckAttr(S, D, AL);
break;
+ case ParsedAttr::AT_Leaf:
+ handleSimpleAttribute<LeafAttr>(S, D, AL);
+ break;
case ParsedAttr::AT_NoThrow:
if (!AL.isUsedAsTypeAttr())
handleSimpleAttribute<NoThrowAttr>(S, D, AL);
diff --git a/clang/test/CodeGen/attr-leaf.c b/clang/test/CodeGen/attr-leaf.c
new file mode 100644
index 000000000000..2b2bacf5e725
--- /dev/null
+++ b/clang/test/CodeGen/attr-leaf.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -Oz -o - %s | FileCheck %s
+
+// CHECK: define void @f() local_unnamed_addr [[ATTRS:#[0-9]+]] {
+void f() __attribute__((leaf));
+
+void f()
+{
+}
+
+// CHECK: attributes [[ATTRS]] = { {{.*}}nocallback{{.*}} }
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 0ba6769a1a8a..cb1e48217a81 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -68,6 +68,7 @@
// CHECK-NEXT: InitPriority (SubjectMatchRule_variable)
// CHECK-NEXT: InternalLinkage (SubjectMatchRule_variable, SubjectMatchRule_function, SubjectMatchRule_record)
// CHECK-NEXT: LTOVisibilityPublic (SubjectMatchRule_record)
+// CHECK-NEXT: Leaf (SubjectMatchRule_function)
// CHECK-NEXT: LoaderUninitialized (SubjectMatchRule_variable_is_global)
// CHECK-NEXT: Lockable (SubjectMatchRule_record)
// CHECK-NEXT: MIGServerRoutine (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_block)
diff --git a/clang/test/Sema/attr-leaf.c b/clang/test/Sema/attr-leaf.c
new file mode 100644
index 000000000000..a28ad79ae791
--- /dev/null
+++ b/clang/test/Sema/attr-leaf.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+
+void f1() __attribute__((leaf));
+
+void f2() __attribute__((leaf("abc"))); // expected-error {{'leaf' attribute takes no argument}}
+
+int var __attribute__ ((leaf())); // expected-warning {{'leaf' attribute only applies to functions}}
+
+// FIXME: Might diagnose a warning if leaf attribute is used in function definition
+// The leaf attribute has no effect on functions defined within the current compilation unit
+__attribute__((leaf)) void f3() {
+}
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
index 80fa4ac97d0d..a6d28024e2e5 100644
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -653,6 +653,7 @@ enum AttributeKindCodes {
ATTR_KIND_NOUNDEF = 68,
ATTR_KIND_BYREF = 69,
ATTR_KIND_MUSTPROGRESS = 70,
+ ATTR_KIND_NO_CALLBACK = 71,
};
enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
index 762f4d69b795..30d297563cb1 100644
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -103,6 +103,9 @@ def NoAlias : EnumAttr<"noalias">;
/// Callee isn't recognized as a builtin.
def NoBuiltin : EnumAttr<"nobuiltin">;
+/// Function cannot enter into caller's translation unit.
+def NoCallback : EnumAttr<"nocallback">;
+
/// Function creates no aliases of pointer.
def NoCapture : EnumAttr<"nocapture">;
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index baabd553fbdf..c50e824d6f18 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -653,6 +653,7 @@ lltok::Kind LLLexer::LexIdentifier() {
KEYWORD(nest);
KEYWORD(noalias);
KEYWORD(nobuiltin);
+ KEYWORD(nocallback);
KEYWORD(nocapture);
KEYWORD(noduplicate);
KEYWORD(nofree);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 675151e6e147..0c2c10700d78 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -1353,6 +1353,9 @@ bool LLParser::parseFnAttributeValuePairs(AttrBuilder &B,
break;
case lltok::kw_naked: B.addAttribute(Attribute::Naked); break;
case lltok::kw_nobuiltin: B.addAttribute(Attribute::NoBuiltin); break;
+ case lltok::kw_nocallback:
+ B.addAttribute(Attribute::NoCallback);
+ break;
case lltok::kw_noduplicate: B.addAttribute(Attribute::NoDuplicate); break;
case lltok::kw_nofree: B.addAttribute(Attribute::NoFree); break;
case lltok::kw_noimplicitfloat:
diff --git a/llvm/lib/AsmParser/LLToken.h b/llvm/lib/AsmParser/LLToken.h
index 7dd0fdab2cbf..32e1165c7745 100644
--- a/llvm/lib/AsmParser/LLToken.h
+++ b/llvm/lib/AsmParser/LLToken.h
@@ -200,6 +200,7 @@ enum Kind {
kw_noalias,
kw_noundef,
kw_nobuiltin,
+ kw_nocallback,
kw_nocapture,
kw_noduplicate,
kw_nofree,
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 158f8d177d66..43e4fca007c6 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1433,6 +1433,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
return Attribute::NoAlias;
case bitc::ATTR_KIND_NO_BUILTIN:
return Attribute::NoBuiltin;
+ case bitc::ATTR_KIND_NO_CALLBACK:
+ return Attribute::NoCallback;
case bitc::ATTR_KIND_NO_CAPTURE:
return Attribute::NoCapture;
case bitc::ATTR_KIND_NO_DUPLICATE:
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 5c13738fad61..5b965186daa8 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -646,6 +646,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
return bitc::ATTR_KIND_NO_ALIAS;
case Attribute::NoBuiltin:
return bitc::ATTR_KIND_NO_BUILTIN;
+ case Attribute::NoCallback:
+ return bitc::ATTR_KIND_NO_CALLBACK;
case Attribute::NoCapture:
return bitc::ATTR_KIND_NO_CAPTURE;
case Attribute::NoDuplicate:
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 82350ad6d29b..fc0d68ebc729 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -371,6 +371,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
return "noalias";
if (hasAttribute(Attribute::NoBuiltin))
return "nobuiltin";
+ if (hasAttribute(Attribute::NoCallback))
+ return "nocallback";
if (hasAttribute(Attribute::NoCapture))
return "nocapture";
if (hasAttribute(Attribute::NoDuplicate))
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index ac44a95d7da5..71bb94e77593 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -1597,6 +1597,7 @@ static bool isFuncOnlyAttr(Attribute::AttrKind Kind) {
case Attribute::NoReturn:
case Attribute::NoSync:
case Attribute::WillReturn:
+ case Attribute::NoCallback:
case Attribute::NoCfCheck:
case Attribute::NoUnwind:
case Attribute::NoInline:
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
index 1d01e40843c5..91297b8dea19 100644
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -946,6 +946,7 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
case Attribute::NoRecurse:
case Attribute::InlineHint:
case Attribute::MinSize:
+ case Attribute::NoCallback:
case Attribute::NoDuplicate:
case Attribute::NoFree:
case Attribute::NoImplicitFloat:
diff --git a/llvm/test/Bitcode/attributes.ll b/llvm/test/Bitcode/attributes.ll
index baafc70cf40b..36c9ff7ca391 100644
--- a/llvm/test/Bitcode/attributes.ll
+++ b/llvm/test/Bitcode/attributes.ll
@@ -404,6 +404,12 @@ define void @f68() mustprogress
ret void
}
+; CHECK; define void @f69() #43
+define void @f70() nocallback
+{
+ ret void
+}
+
; CHECK: attributes #0 = { noreturn }
; CHECK: attributes #1 = { nounwind }
; CHECK: attributes #2 = { readnone }
@@ -446,4 +452,5 @@ define void @f68() mustprogress
; CHECK: attributes #39 = { sanitize_memtag }
; CHECK: attributes #40 = { null_pointer_is_valid }
; CHECK: attributes #41 = { mustprogress }
+; CHECK: attributes #42 = { nocallback }
; CHECK: attributes #[[NOBUILTIN]] = { nobuiltin }
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