[Clang] Add __builtin_stack_address

llvm/docs/LangRef.rst

@@ -14417,8 +14417,6 @@ register are the same. However, on other architectures (e.g. SPARCv9), the logic
 stack pointer register may differ from the physical value. '``llvm.stackaddress``' handles this
 discrepancy and returns the correct boundary address.
 
-**Note**: This intrinsic is currently only implemented for x86 and x86-64.
-
 '``llvm.frameaddress``' Intrinsic
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

llvm/test/CodeGen/ARM/stackaddress.ll

@@ -0,0 +1,14 @@
+; RUN: llc < %s -mtriple=armv7 | FileCheck %s --check-prefix=armv7
+; RUN: llc < %s -mtriple=aarch64 | FileCheck %s --check-prefix=aarch64
+
+declare ptr @llvm.stackaddress.p0()
+
+define ptr @test() {
+; armv7: mov r0, sp
+; armv7: bx  lr
+
+; aarch64: mov x0, sp
+; aarch64: ret
+  %sp = call ptr @llvm.stackaddress.p0()
+  ret ptr %sp
+}

llvm/test/CodeGen/X86/stackaddress.ll

@@ -0,0 +1,14 @@
+; RUN: llc < %s -mtriple=x86_64-linux-gnu -o - | FileCheck --check-prefix=x86_64 %s
+; RUN: llc < %s -mtriple=i386-linux-gnu -o -   | FileCheck --check-prefix=i386   %s
+
+declare ptr @llvm.stackaddress.p0()
+
+define ptr @test() {
+; x86_64: movq %rsp, %rax
+; x86_64: retq
+
+; i386: movl %esp, %eax
+; i386: retl
+  %sp = call ptr @llvm.stackaddress.p0()
+  ret ptr %sp
+}