[GCC] Attribute ifunc support in clang

This patch add support for GCC attribute((ifunc("resolver"))) for
targets that use ELF as object file format. In general ifunc is a
special kind of function alias with type @gnu_indirect_function. LLVM
patch http://reviews.llvm.org/D15525

Differential Revision: http://reviews.llvm.org/D15524

llvm-svn: 265917

3 files changed, 85 insertions, 1 deletions

diff --git a/clang/test/CodeGen/ifunc.c b/clang/test/CodeGen/ifunc.c
new file mode 100644
index 00000000000..a88bb1878f2
--- /dev/null
+++ b/clang/test/CodeGen/ifunc.c
@@ -0,0 +1,41 @@
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -O2 -emit-llvm -o - %s | FileCheck %s
+
+int foo(int) __attribute__ ((ifunc("foo_ifunc")));
+
+static int f1(int i) {
+  return i + 1;
+}
+
+static int f2(int i) {
+  return i + 2;
+}
+
+typedef int (*foo_t)(int);
+
+int global;
+
+static foo_t foo_ifunc() {
+  return global ? f1 : f2;
+}
+
+int bar() {
+  return foo(1);
+}
+
+extern void goo(void);
+
+void bar2(void) {
+  goo();
+}
+
+extern void goo(void) __attribute__ ((ifunc("goo_ifunc")));
+
+void* goo_ifunc(void) {
+  return 0;
+}
+// CHECK: @foo = ifunc i32 (i32), bitcast (i32 (i32)* ()* @foo_ifunc to i32 (i32)*)
+// CHECK: @goo = ifunc void (), bitcast (i8* ()* @goo_ifunc to void ()*)
+
+// CHECK: call i32 @foo(i32
+// CHECK: call void @goo()
diff --git a/clang/test/Sema/attr-alias-elf.c b/clang/test/Sema/attr-alias-elf.c
index f14514dccd2..e56f23e4fa5 100644
--- a/clang/test/Sema/attr-alias-elf.c
+++ b/clang/test/Sema/attr-alias-elf.c
@@ -55,7 +55,7 @@ typedef int b4;
 
 void test2_bar() {}
 void test2_foo() __attribute__((weak, alias("test2_bar")));
-void test2_zed() __attribute__((alias("test2_foo"))); // expected-warning {{alias will always resolve to test2_bar even if weak definition of alias test2_foo is overridden}}
+void test2_zed() __attribute__((alias("test2_foo"))); // expected-warning {{alias will always resolve to test2_bar even if weak definition of test2_foo is overridden}}
 
 void test3_bar() { }
 void test3_foo() __attribute__((section("test"))); // expected-warning {{alias will not be in section 'test' but in the same section as the aliasee}}
diff --git a/clang/test/Sema/attr-ifunc.c b/clang/test/Sema/attr-ifunc.c
new file mode 100644
index 00000000000..76473c7e5cb
--- /dev/null
+++ b/clang/test/Sema/attr-ifunc.c
@@ -0,0 +1,43 @@
+// RUN: %clang_cc1 -triple x86_64-windows -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple x86_64-linux -fsyntax-only -verify -emit-llvm -DCHECK_ALIASES %s
+// RUN: %clang_cc1 -triple x86_64-linux -fsyntax-only -verify -emit-llvm %s
+
+#if defined(_WIN32)
+void foo() {}
+void bar() __attribute__((ifunc("foo")));
+//expected-warning@-1 {{'ifunc' attribute ignored}}
+
+#else
+#if defined(CHECK_ALIASES)
+void* f1_ifunc();
+void f1() __attribute__((ifunc("f1_ifunc")));
+//expected-error@-1 {{ifunc must point to a defined function}}
+
+void* f2_a() __attribute__((ifunc("f2_b")));
+//expected-error@-1 {{ifunc definition is part of a cycle}}
+void* f2_b() __attribute__((ifunc("f2_a")));
+//expected-error@-1 {{ifunc definition is part of a cycle}}
+
+void* f3_a() __attribute__((ifunc("f3_b")));
+//expected-warning@-1 {{ifunc will always resolve to f3_c even if weak definition of f3_b is overridden}}
+void* f3_b() __attribute__((weak, alias("f3_c")));
+void* f3_c() { return 0; }
+
+void f4_ifunc() {}
+void f4() __attribute__((ifunc("f4_ifunc")));
+//expected-error@-1 {{ifunc resolver function must return a pointer}}
+
+void* f5_ifunc(int i) { return 0; }
+void f5() __attribute__((ifunc("f5_ifunc")));
+//expected-error@-1 {{ifunc resolver function must have no parameters}}
+
+#else
+void f1a() __asm("f1");
+void f1a() {}
+//expected-note@-1 {{previous definition is here}}
+void f1() __attribute__((ifunc("f1_ifunc")));
+//expected-error@-1 {{definition with same mangled name as another definition}}
+void* f1_ifunc() { return 0; }
+
+#endif
+#endif