[clang] Function Multi Versioning supports IFunc lowerings on Darwin platforms

clang/include/clang/Basic/Attr.td

@@ -455,6 +455,9 @@ def TargetMicrosoftCXXABI : TargetArch<["x86", "x86_64", "arm", "thumb", "aarch6
 def TargetELF : TargetSpec {
   let ObjectFormats = ["ELF"];
 }
+def TargetELFOrMachO : TargetSpec {
+  let ObjectFormats = ["ELF", "MachO"];
+}
 
 def TargetSupportsInitPriority : TargetSpec {
   let CustomCode = [{ !Target.getTriple().isOSzOS() }];
@@ -1665,7 +1668,7 @@ def IBOutletCollection : InheritableAttr {
   let Documentation = [Undocumented];
 }
 
-def IFunc : Attr, TargetSpecificAttr<TargetELF> {
+def IFunc : Attr, TargetSpecificAttr<TargetELFOrMachO> {
   let Spellings = [GCC<"ifunc">];
   let Args = [StringArgument<"Resolver">];
   let Subjects = SubjectList<[Function]>;

clang/include/clang/Basic/AttrDocs.td

@@ -5535,7 +5535,9 @@ considered inline.
 Not all targets support this attribute. ELF target support depends on both the
 linker and runtime linker, and is available in at least lld 4.0 and later,
 binutils 2.20.1 and later, glibc v2.11.1 and later, and FreeBSD 9.1 and later.
-Non-ELF targets currently do not support this attribute.
+Mach-O targets support it, but with slightly different semantics: the resolver
+is run at first call, instead of at load time by the runtime linker. Targets
+other than ELF and Mach-O currently do not support this attribute.
   }];
 }
 

clang/include/clang/Basic/TargetInfo.h

@@ -1423,6 +1423,8 @@ class TargetInfo : public TransferrableTargetInfo,
 
   /// Identify whether this target supports IFuncs.
   bool supportsIFunc() const {
+    if (getTriple().isOSBinFormatMachO())
+      return true;
     return getTriple().isOSBinFormatELF() &&
            ((getTriple().isOSLinux() && !getTriple().isMusl()) ||
             getTriple().isOSFreeBSD());

clang/test/CodeGen/attr-cpuspecific.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,LINUX
+// RUN: %clang_cc1 -triple x86_64-apple-macos -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,LINUX
 // RUN: %clang_cc1 -triple x86_64-windows-pc -fms-compatibility -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,WINDOWS
 
 #ifdef _WIN64

clang/test/CodeGen/attr-ifunc.c

@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-windows -fsyntax-only -verify %s
 // RUN: %clang_cc1 -triple x86_64-linux -fsyntax-only -verify -emit-llvm-only -DCHECK_ALIASES %s
 // RUN: %clang_cc1 -triple x86_64-linux -fsyntax-only -verify -emit-llvm-only %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx -fsyntax-only -verify -emit-llvm-only %s
 
 #if defined(_WIN32)
 void foo(void) {}
@@ -36,6 +37,25 @@ void *f6_resolver(void) __attribute__((ifunc("f6_resolver_resolver")));
 void f6(void) __attribute__((ifunc("f6_resolver")));
 // expected-error@-1 {{ifunc must point to a defined function}}
 
+#elif defined(__APPLE__)
+
+// NOTE: aliases are not supported on Darwin, so the above tests are not relevant.
+
+#define STR2(X) #X
+#define STR(X) STR2(X)
+#define PREFIX STR(__USER_LABEL_PREFIX__)
+
+void f1a(void) __asm("f1");
+void f1a(void) {}
+// expected-note@-1 {{previous definition is here}}
+void f1(void) __attribute__((ifunc(PREFIX "f1_ifunc"))) __asm("f1");
+// expected-error@-1 {{definition with same mangled name '<U+0001>f1' as another definition}}
+void *f1_ifunc(void) { return 0; }
+
+void *f6_ifunc(int i);
+void __attribute__((ifunc(PREFIX "f6_ifunc"))) f6(void) {}
+// expected-error@-1 {{definition 'f6' cannot also be an ifunc}}
+
 #else
 void f1a(void) __asm("f1");
 void f1a(void) {}

clang/test/CodeGen/attr-ifunc.cpp

@@ -1,5 +1,9 @@
 // RUN: %clang_cc1 -triple x86_64-linux -fsyntax-only -verify -emit-llvm-only %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx -fsyntax-only -verify -emit-llvm-only %s
+// RUN: %clang_cc1 -triple arm64-apple-macosx -fsyntax-only -verify -emit-llvm-only %s
 // RUN: not %clang_cc1 -triple x86_64-linux -emit-llvm-only -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: not %clang_cc1 -triple x86_64-apple-macosx -emit-llvm-only -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: not %clang_cc1 -triple arm64-apple-macosx -emit-llvm-only -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
 
 void *f1_ifunc(void) { return nullptr; }
 void f1(void) __attribute__((ifunc("f1_ifunc")));

clang/test/CodeGen/attr-target-clones.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefixes=LINUX,CHECK
+// RUN: %clang_cc1 -triple x86_64-apple-macos -emit-llvm %s -o - | FileCheck %s --check-prefixes=DARWIN,CHECK
 // RUN: %clang_cc1 -triple x86_64-windows-pc -emit-llvm %s -o - | FileCheck %s --check-prefixes=WINDOWS,CHECK
 
 // LINUX: $foo.resolver = comdat any
@@ -7,6 +8,8 @@
 // LINUX: $foo_inline.resolver = comdat any
 // LINUX: $foo_inline2.resolver = comdat any
 
+// DARWIN-NOT: comdat any
+
 // WINDOWS: $foo = comdat any
 // WINDOWS: $foo_dupes = comdat any
 // WINDOWS: $unused = comdat any
@@ -16,6 +19,9 @@
 // LINUX: @__cpu_model = external dso_local global { i32, i32, i32, [1 x i32] }
 // LINUX: @__cpu_features2 = external dso_local global [3 x i32]
 
+// DARWIN: @__cpu_model = external dso_local global { i32, i32, i32, [1 x i32] }
+// DARWIN: @__cpu_features2 = external dso_local global [3 x i32]
+
 // LINUX: @internal.ifunc = internal alias i32 (), ptr @internal
 // LINUX: @foo.ifunc = weak_odr alias i32 (), ptr @foo
 // LINUX: @foo_dupes.ifunc = weak_odr alias void (), ptr @foo_dupes
@@ -34,10 +40,12 @@
 // LINUX: @foo_used_no_defn = weak_odr ifunc i32 (), ptr @foo_used_no_defn.resolver
 // LINUX: @isa_level = weak_odr ifunc i32 (i32), ptr @isa_level.resolver
 
+
 static int __attribute__((target_clones("sse4.2, default"))) internal(void) { return 0; }
 int use(void) { return internal(); }
 /// Internal linkage resolvers do not use comdat.
 // LINUX: define internal ptr @internal.resolver() {
+// DARWIN: define internal ptr @internal.resolver() {
 // WINDOWS: define internal i32 @internal() {
 
 int __attribute__((target_clones("sse4.2, default"))) foo(void) { return 0; }
@@ -47,6 +55,12 @@ int __attribute__((target_clones("sse4.2, default"))) foo(void) { return 0; }
 // LINUX: ret ptr @foo.sse4.2.0
 // LINUX: ret ptr @foo.default.1
 
+// DARWIN: define {{.*}}i32 @foo.sse4.2.0()
+// DARWIN: define {{.*}}i32 @foo.default.1()
+// DARWIN: define weak_odr ptr @foo.resolver() {
+// DARWIN: ret ptr @foo.sse4.2.0
+// DARWIN: ret ptr @foo.default.1
+
 // WINDOWS: define dso_local i32 @foo.sse4.2.0()
 // WINDOWS: define dso_local i32 @foo.default.1()
 // WINDOWS: define weak_odr dso_local i32 @foo() comdat
@@ -60,6 +74,12 @@ __attribute__((target_clones("default,default ,sse4.2"))) void foo_dupes(void) {
 // LINUX: ret ptr @foo_dupes.sse4.2.0
 // LINUX: ret ptr @foo_dupes.default.1
 
+// DARWIN: define {{.*}}void @foo_dupes.default.1()
+// DARWIN: define {{.*}}void @foo_dupes.sse4.2.0()
+// DARWIN: define weak_odr ptr @foo_dupes.resolver() {
+// DARWIN: ret ptr @foo_dupes.sse4.2.0
+// DARWIN: ret ptr @foo_dupes.default.1
+
 // WINDOWS: define dso_local void @foo_dupes.default.1()
 // WINDOWS: define dso_local void @foo_dupes.sse4.2.0()
 // WINDOWS: define weak_odr dso_local void @foo_dupes() comdat
@@ -68,17 +88,21 @@ __attribute__((target_clones("default,default ,sse4.2"))) void foo_dupes(void) {
 
 void bar2(void) {
   // LINUX: define {{.*}}void @bar2()
+  // DARWIN: define {{.*}}void @bar2()
   // WINDOWS: define dso_local void @bar2()
   foo_dupes();
   // LINUX: call void @foo_dupes()
+  // DARWIN: call void @foo_dupes()
   // WINDOWS: call void @foo_dupes()
 }
 
 int bar(void) {
   // LINUX: define {{.*}}i32 @bar() #[[DEF:[0-9]+]]
+  // DARWIN: define {{.*}}i32 @bar() #[[DEF:[0-9]+]]
   // WINDOWS: define dso_local i32 @bar() #[[DEF:[0-9]+]]
   return foo();
   // LINUX: call i32 @foo()
+  // DARWIN: call i32 @foo()
   // WINDOWS: call i32 @foo()
 }
 
@@ -89,6 +113,12 @@ void __attribute__((target_clones("default, arch=ivybridge"))) unused(void) {}
 // LINUX: ret ptr @unused.arch_ivybridge.0
 // LINUX: ret ptr @unused.default.1
 
+// DARWIN: define {{.*}}void @unused.default.1()
+// DARWIN: define {{.*}}void @unused.arch_ivybridge.0()
+// DARWIN: define weak_odr ptr @unused.resolver() {
+// DARWIN: ret ptr @unused.arch_ivybridge.0
+// DARWIN: ret ptr @unused.default.1
+
 // WINDOWS: define dso_local void @unused.default.1()
 // WINDOWS: define dso_local void @unused.arch_ivybridge.0()
 // WINDOWS: define weak_odr dso_local void @unused() comdat
@@ -103,10 +133,13 @@ foo_inline2(void);
 
 int bar3(void) {
   // LINUX: define {{.*}}i32 @bar3()
+  // DARWIN: define {{.*}}i32 @bar3()
   // WINDOWS: define dso_local i32 @bar3()
   return foo_inline() + foo_inline2();
   // LINUX: call i32 @foo_inline()
   // LINUX: call i32 @foo_inline2()
+  // DARWIN: call i32 @foo_inline()
+  // DARWIN: call i32 @foo_inline2()
   // WINDOWS: call i32 @foo_inline()
   // WINDOWS: call i32 @foo_inline2()
 }
@@ -116,6 +149,11 @@ int bar3(void) {
 // LINUX: ret ptr @foo_inline.sse4.2.1
 // LINUX: ret ptr @foo_inline.default.2
 
+// DARWIN: define weak_odr ptr @foo_inline.resolver() {
+// DARWIN: ret ptr @foo_inline.arch_sandybridge.0
+// DARWIN: ret ptr @foo_inline.sse4.2.1
+// DARWIN: ret ptr @foo_inline.default.2
+
 // WINDOWS: define weak_odr dso_local i32 @foo_inline() comdat
 // WINDOWS: musttail call i32 @foo_inline.arch_sandybridge.0
 // WINDOWS: musttail call i32 @foo_inline.sse4.2.1
@@ -128,6 +166,11 @@ foo_inline2(void){ return 0; }
 // LINUX: ret ptr @foo_inline2.sse4.2.1
 // LINUX: ret ptr @foo_inline2.default.2
 
+// DARWIN: define weak_odr ptr @foo_inline2.resolver() {
+// DARWIN: ret ptr @foo_inline2.arch_sandybridge.0
+// DARWIN: ret ptr @foo_inline2.sse4.2.1
+// DARWIN: ret ptr @foo_inline2.default.2
+
 // WINDOWS: define weak_odr dso_local i32 @foo_inline2() comdat
 // WINDOWS: musttail call i32 @foo_inline2.arch_sandybridge.0
 // WINDOWS: musttail call i32 @foo_inline2.sse4.2.1
@@ -142,9 +185,11 @@ foo_used_no_defn(void);
 
 int test_foo_used_no_defn(void) {
   // LINUX: define {{.*}}i32 @test_foo_used_no_defn()
+  // DARWIN: define {{.*}}i32 @test_foo_used_no_defn()
   // WINDOWS: define dso_local i32 @test_foo_used_no_defn()
   return foo_used_no_defn();
   // LINUX: call i32 @foo_used_no_defn()
+  // DARWIN: call i32 @foo_used_no_defn()
   // WINDOWS: call i32 @foo_used_no_defn()
 }
 
@@ -153,6 +198,10 @@ int test_foo_used_no_defn(void) {
 // LINUX: ret ptr @foo_used_no_defn.sse4.2.0
 // LINUX: ret ptr @foo_used_no_defn.default.1
 
+// DARWIN: define weak_odr ptr @foo_used_no_defn.resolver() {
+// DARWIN: ret ptr @foo_used_no_defn.sse4.2.0
+// DARWIN: ret ptr @foo_used_no_defn.default.1
+
 // WINDOWS: define weak_odr dso_local i32 @foo_used_no_defn() comdat
 // WINDOWS: musttail call i32 @foo_used_no_defn.sse4.2.0
 // WINDOWS: musttail call i32 @foo_used_no_defn.default.1
@@ -180,12 +229,37 @@ int isa_level(int) { return 0; }
 // LINUX:        ret ptr @isa_level.arch_x86-64.0
 // LINUX:        ret ptr @isa_level.default.4
 
+// DARWIN:      define{{.*}} i32 @isa_level.default.4(
+// DARWIN:      define{{.*}} i32 @isa_level.arch_x86-64.0(
+// DARWIN:      define{{.*}} i32 @isa_level.arch_x86-64-v2.1(
+// DARWIN:      define{{.*}} i32 @isa_level.arch_x86-64-v3.2(
+// DARWIN:      define{{.*}} i32 @isa_level.arch_x86-64-v4.3(
+// DARWIN:      define weak_odr ptr @isa_level.resolver() {
+// DARWIN:        call void @__cpu_indicator_init()
+// DARWIN-NEXT:   load i32, ptr getelementptr inbounds ([3 x i32], ptr @__cpu_features2, i32 0, i32 2)
+// DARWIN-NEXT:   and i32 %[[#]], 4
+// DARWIN:        ret ptr @isa_level.arch_x86-64-v4.3
+// DARWIN:        load i32, ptr getelementptr inbounds ([3 x i32], ptr @__cpu_features2, i32 0, i32 2)
+// DARWIN-NEXT:   and i32 %[[#]], 2
+// DARWIN:        ret ptr @isa_level.arch_x86-64-v3.2
+// DARWIN:        load i32, ptr getelementptr inbounds ([3 x i32], ptr @__cpu_features2, i32 0, i32 2)
+// DARWIN-NEXT:   and i32 %[[#]], 1
+// DARWIN:        ret ptr @isa_level.arch_x86-64-v2.1
+// DARWIN:        load i32, ptr getelementptr inbounds ([3 x i32], ptr @__cpu_features2, i32 0, i32 1)
+// DARWIN-NEXT:   and i32 %[[#]], -2147483648
+// DARWIN:        ret ptr @isa_level.arch_x86-64.0
+// DARWIN:        ret ptr @isa_level.default.4
+
 // Deferred emission of inline definitions.
 
 // LINUX: define linkonce i32 @foo_inline.arch_sandybridge.0() #[[SB:[0-9]+]]
 // LINUX: define linkonce i32 @foo_inline.default.2() #[[DEF:[0-9]+]]
 // LINUX: define linkonce i32 @foo_inline.sse4.2.1() #[[SSE42:[0-9]+]]
 
+// DARWIN: define linkonce i32 @foo_inline.arch_sandybridge.0() #[[SB:[0-9]+]]
+// DARWIN: define linkonce i32 @foo_inline.default.2() #[[DEF:[0-9]+]]
+// DARWIN: define linkonce i32 @foo_inline.sse4.2.1() #[[SSE42:[0-9]+]]
+
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline.arch_sandybridge.0() #[[SB:[0-9]+]]
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline.default.2() #[[DEF]]
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline.sse4.2.1() #[[SSE42:[0-9]+]]
@@ -195,6 +269,10 @@ int isa_level(int) { return 0; }
 // LINUX: define linkonce i32 @foo_inline2.default.2() #[[DEF]]
 // LINUX: define linkonce i32 @foo_inline2.sse4.2.1() #[[SSE42]]
 
+// DARWIN: define linkonce i32 @foo_inline2.arch_sandybridge.0() #[[SB]]
+// DARWIN: define linkonce i32 @foo_inline2.default.2() #[[DEF]]
+// DARWIN: define linkonce i32 @foo_inline2.sse4.2.1() #[[SSE42]]
+
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline2.arch_sandybridge.0() #[[SB]]
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline2.default.2() #[[DEF]]
 // WINDOWS: define linkonce_odr dso_local i32 @foo_inline2.sse4.2.1() #[[SSE42]]
@@ -203,6 +281,9 @@ int isa_level(int) { return 0; }
 // LINUX: declare i32 @foo_used_no_defn.default.1()
 // LINUX: declare i32 @foo_used_no_defn.sse4.2.0()
 
+// DARWIN: declare i32 @foo_used_no_defn.default.1()
+// DARWIN: declare i32 @foo_used_no_defn.sse4.2.0()
+
 // WINDOWS: declare dso_local i32 @foo_used_no_defn.default.1()
 // WINDOWS: declare dso_local i32 @foo_used_no_defn.sse4.2.0()
 

clang/test/CodeGen/attr-target-mv-func-ptrs.c

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefix=LINUX
+// RUN: %clang_cc1 -triple x86_64-apple-macos -emit-llvm %s -o - | FileCheck %s --check-prefix=LINUX
 // RUN: %clang_cc1 -triple x86_64-windows-pc -emit-llvm %s -o - | FileCheck %s --check-prefix=WINDOWS
 int __attribute__((target("sse4.2"))) foo(int i) { return 0; }
 int __attribute__((target("arch=sandybridge"))) foo(int);

clang/test/CodeGen/attr-target-mv-va-args.c

@@ -3,6 +3,7 @@
 // RUN: %clang_cc1 -triple x86_64-windows-pc -emit-llvm %s -o - | FileCheck %s --check-prefixes=NO-IFUNC,WINDOWS
 // RUN: %clang_cc1 -triple x86_64-linux-musl -emit-llvm %s -o - | FileCheck %s --check-prefixes=NO-IFUNC,NO-IFUNC-ELF
 // RUN: %clang_cc1 -triple x86_64-fuchsia -emit-llvm %s -o - | FileCheck %s --check-prefixes=NO-IFUNC,NO-IFUNC-ELF
+// RUN: %clang_cc1 -triple x86_64-apple-macho -emit-llvm %s -o - | FileCheck %s --check-prefix=IFUNC-MACHO
 int __attribute__((target("sse4.2"))) foo(int i, ...) { return 0; }
 int __attribute__((target("arch=sandybridge"))) foo(int i, ...);
 int __attribute__((target("arch=ivybridge"))) foo(int i, ...) {return 1;}
@@ -30,6 +31,24 @@ int bar(void) {
 // IFUNC-ELF: ret ptr @foo
 // IFUNC-ELF: declare i32 @foo.arch_sandybridge(i32 noundef, ...)
 
+// IFUNC-MACHO: @foo.ifunc = weak_odr ifunc i32 (i32, ...), ptr @foo.resolver
+// IFUNC-MACHO: define{{.*}} i32 @foo.sse4.2(i32 noundef %i, ...)
+// IFUNC-MACHO: ret i32 0
+// IFUNC-MACHO: define{{.*}} i32 @foo.arch_ivybridge(i32 noundef %i, ...)
+// IFUNC-MACHO: ret i32 1
+// IFUNC-MACHO: define{{.*}} i32 @foo(i32 noundef %i, ...)
+// IFUNC-MACHO: ret i32 2
+// IFUNC-MACHO: define{{.*}} i32 @bar()
+// IFUNC-MACHO: call i32 (i32, ...) @foo.ifunc(i32 noundef 1, i32 noundef 97, double
+// IFUNC-MACHO: call i32 (i32, ...) @foo.ifunc(i32 noundef 2, double noundef 2.2{{[0-9Ee+]+}}, ptr noundef
+
+// IFUNC-MACHO: define weak_odr ptr @foo.resolver()
+// IFUNC-MACHO: ret ptr @foo.arch_sandybridge
+// IFUNC-MACHO: ret ptr @foo.arch_ivybridge
+// IFUNC-MACHO: ret ptr @foo.sse4.2
+// IFUNC-MACHO: ret ptr @foo
+// IFUNC-MACHO: declare i32 @foo.arch_sandybridge(i32 noundef, ...)
+
 // NO-IFUNC: define dso_local i32 @foo.sse4.2(i32 noundef %i, ...)
 // NO-IFUNC: ret i32 0
 // NO-IFUNC: define dso_local i32 @foo.arch_ivybridge(i32 noundef %i, ...)