[GCC] Attribute ifunc support in llvm

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. Patch
for Clang http://reviews.llvm.org/D15524

Differential Revision: http://reviews.llvm.org/D15525

llvm-svn: 265667

3 files changed, 81 insertions, 0 deletions

diff --git a/llvm/test/Assembler/ifunc-asm.ll b/llvm/test/Assembler/ifunc-asm.ll
new file mode 100644
index 00000000000..7c30a35613a
--- /dev/null
+++ b/llvm/test/Assembler/ifunc-asm.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s --check-prefix=CHECK-LLVM
+; RUN: llvm-as < %s -o - | llc -filetype=asm | FileCheck %s --check-prefix=CHECK-ASM
+
+target triple = "x86_64-unknown-linux-gnu"
+
+@foo = ifunc i32 (i32), i64 ()* @foo_ifunc
+; CHECK-LLVM: @foo = ifunc i32 (i32), i64 ()* @foo_ifunc
+; CHECK-ASM: .type   foo,@gnu_indirect_function
+
+define internal i64 @foo_ifunc() {
+entry:
+  ret i64 0
+}
+; CHECK-LLVM: define internal i64 @foo_ifunc()
diff --git a/llvm/test/Assembler/ifunc-use-list-order.ll b/llvm/test/Assembler/ifunc-use-list-order.ll
new file mode 100644
index 00000000000..efd8dcc3f87
--- /dev/null
+++ b/llvm/test/Assembler/ifunc-use-list-order.ll
@@ -0,0 +1,42 @@
+; RUN: verify-uselistorder < %s
+
+; Global referencing ifunc.
+@ptr_foo = global void ()* @foo_ifunc
+
+; Alias for ifunc.
+@alias_foo = alias void (), void ()* @foo_ifunc
+
+@foo_ifunc = ifunc void (), i8* ()* @foo_resolver
+
+define i8* @foo_resolver() {
+entry:
+  ret i8* null
+}
+
+; Function referencing ifunc.
+define void @bar() {
+entry:
+  call void @foo_ifunc()
+  ret void
+}
+
+; Global referencing function.
+@ptr_bar = global void ()* @bar
+
+; Alias for function.
+@alias_bar = alias void (), void ()* @bar
+
+@bar_ifunc = ifunc void (), i8* ()* @bar2_ifunc
+@bar2_ifunc = ifunc i8* (), i8* ()* @bar_resolver
+
+define i8* @bar_resolver() {
+entry:
+  ret i8* null
+}
+
+; Function referencing bar.
+define void @bar2() {
+entry:
+  call void @bar()
+  ret void
+}
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
index ae12a24ede4..d1f249114d5 100644
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -249,6 +249,31 @@ declare void @g.f1()
 @a.unnamed_addr = unnamed_addr alias i32, i32* @g.unnamed_addr
 ; CHECK: @a.unnamed_addr = unnamed_addr alias i32, i32* @g.unnamed_addr
 
+;; IFunc
+; Format @<Name> = [Linkage] [Visibility] ifunc <IFuncTy>,
+;                  <ResolverTy>* @<Resolver>
+
+; IFunc -- Linkage
+@ifunc.external = external ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.external = ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.private = private ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.internal = internal ifunc void (), i8* ()* @ifunc_resolver
+
+; IFunc -- Visibility
+@ifunc.default = default ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.default = ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.hidden = hidden ifunc void (), i8* ()* @ifunc_resolver
+@ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
+; CHECK: @ifunc.protected = protected ifunc void (), i8* ()* @ifunc_resolver
+
+define i8* @ifunc_resolver() {
+entry:
+  ret i8* null
+}
+
 ;; Functions
 ; Format: define [linkage] [visibility] [DLLStorageClass]
 ;         [cconv] [ret attrs]