Rollup merge of #40702 - mrhota:global_asm, r=nagisa

Implement global_asm!() (RFC 1548)

This is a first attempt. ~~One (potential) problem I haven't solved is how to handle multiple usages of `global_asm!` in a module/crate. It looks like `LLVMSetModuleInlineAsm` overwrites module asm, and `LLVMAppendModuleInlineAsm` is not provided in LLVM C headers 😦~~

I can provide more detail as needed, but honestly, there's not a lot going on here.

r? @eddyb

CC @Amanieu @jackpot51

Tracking issue: #35119

4 files changed, 234 insertions, 0 deletions

diff --git a/src/test/codegen/foo.s b/src/test/codegen/foo.s
new file mode 100644
index 00000000000..304d82aa0c6
--- /dev/null
+++ b/src/test/codegen/foo.s
@@ -0,0 +1,3 @@
+.global foo
+foo:
+    jmp baz
diff --git a/src/test/codegen/global_asm.rs b/src/test/codegen/global_asm.rs
new file mode 100644
index 00000000000..5bd0c1b4076
--- /dev/null
+++ b/src/test/codegen/global_asm.rs
@@ -0,0 +1,73 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-aarch64
+// ignore-aarch64_be
+// ignore-arm
+// ignore-armeb
+// ignore-avr
+// ignore-bpfel
+// ignore-bpfeb
+// ignore-hexagon
+// ignore-mips
+// ignore-mipsel
+// ignore-mips64
+// ignore-mips64el
+// ignore-msp430
+// ignore-powerpc64
+// ignore-powerpc64le
+// ignore-powerpc
+// ignore-r600
+// ignore-amdgcn
+// ignore-sparc
+// ignore-sparcv9
+// ignore-sparcel
+// ignore-s390x
+// ignore-tce
+// ignore-thumb
+// ignore-thumbeb
+// ignore-xcore
+// ignore-nvptx
+// ignore-nvptx64
+// ignore-le32
+// ignore-le64
+// ignore-amdil
+// ignore-amdil64
+// ignore-hsail
+// ignore-hsail64
+// ignore-spir
+// ignore-spir64
+// ignore-kalimba
+// ignore-shave
+// ignore-wasm32
+// ignore-wasm64
+// ignore-emscripten
+// compile-flags: -C no-prepopulate-passes
+
+#![feature(global_asm)]
+#![crate_type = "lib"]
+
+// CHECK-LABEL: foo
+// CHECK: module asm
+// this regex will capture the correct unconditional branch inst.
+// CHECK: module asm "{{[[:space:]]+}}jmp baz"
+global_asm!(r#"
+    .global foo
+foo:
+    jmp baz
+"#);
+
+extern "C" {
+    fn foo();
+}
+
+// CHECK-LABEL: @baz
+#[no_mangle]
+pub unsafe extern "C" fn baz() {}
diff --git a/src/test/codegen/global_asm_include.rs b/src/test/codegen/global_asm_include.rs
new file mode 100644
index 00000000000..401b1fad566
--- /dev/null
+++ b/src/test/codegen/global_asm_include.rs
@@ -0,0 +1,68 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-aarch64
+// ignore-aarch64_be
+// ignore-arm
+// ignore-armeb
+// ignore-avr
+// ignore-bpfel
+// ignore-bpfeb
+// ignore-hexagon
+// ignore-mips
+// ignore-mipsel
+// ignore-mips64
+// ignore-mips64el
+// ignore-msp430
+// ignore-powerpc64
+// ignore-powerpc64le
+// ignore-powerpc
+// ignore-r600
+// ignore-amdgcn
+// ignore-sparc
+// ignore-sparcv9
+// ignore-sparcel
+// ignore-s390x
+// ignore-tce
+// ignore-thumb
+// ignore-thumbeb
+// ignore-xcore
+// ignore-nvptx
+// ignore-nvptx64
+// ignore-le32
+// ignore-le64
+// ignore-amdil
+// ignore-amdil64
+// ignore-hsail
+// ignore-hsail64
+// ignore-spir
+// ignore-spir64
+// ignore-kalimba
+// ignore-shave
+// ignore-wasm32
+// ignore-wasm64
+// ignore-emscripten
+// compile-flags: -C no-prepopulate-passes
+
+#![feature(global_asm)]
+#![crate_type = "lib"]
+
+// CHECK-LABEL: foo
+// CHECK: module asm
+// CHECK: module asm "{{[[:space:]]+}}jmp baz"
+global_asm!(include_str!("foo.s"));
+
+extern "C" {
+    fn foo();
+}
+
+// CHECK-LABEL: @baz
+#[no_mangle]
+pub unsafe extern "C" fn baz() {}
diff --git a/src/test/codegen/global_asm_x2.rs b/src/test/codegen/global_asm_x2.rs
new file mode 100644
index 00000000000..8b59165e9e6
--- /dev/null
+++ b/src/test/codegen/global_asm_x2.rs
@@ -0,0 +1,90 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-aarch64
+// ignore-aarch64_be
+// ignore-arm
+// ignore-armeb
+// ignore-avr
+// ignore-bpfel
+// ignore-bpfeb
+// ignore-hexagon
+// ignore-mips
+// ignore-mipsel
+// ignore-mips64
+// ignore-mips64el
+// ignore-msp430
+// ignore-powerpc64
+// ignore-powerpc64le
+// ignore-powerpc
+// ignore-r600
+// ignore-amdgcn
+// ignore-sparc
+// ignore-sparcv9
+// ignore-sparcel
+// ignore-s390x
+// ignore-tce
+// ignore-thumb
+// ignore-thumbeb
+// ignore-xcore
+// ignore-nvptx
+// ignore-nvptx64
+// ignore-le32
+// ignore-le64
+// ignore-amdil
+// ignore-amdil64
+// ignore-hsail
+// ignore-hsail64
+// ignore-spir
+// ignore-spir64
+// ignore-kalimba
+// ignore-shave
+// ignore-wasm32
+// ignore-wasm64
+// ignore-emscripten
+// compile-flags: -C no-prepopulate-passes
+
+#![feature(global_asm)]
+#![crate_type = "lib"]
+#[no_std]
+
+// CHECK-LABEL: foo
+// CHECK: module asm
+// CHECK: module asm "{{[[:space:]]+}}jmp baz"
+// any other global_asm will be appended to this first block, so:
+// CHECK-LABEL: bar
+// CHECK: module asm "{{[[:space:]]+}}jmp quux"
+global_asm!(r#"
+    .global foo
+foo:
+    jmp baz
+"#);
+
+extern "C" {
+    fn foo();
+}
+
+// CHECK-LABEL: @baz
+#[no_mangle]
+pub unsafe extern "C" fn baz() {}
+
+// no checks here; this has been appended to the first occurrence
+global_asm!(r#"
+    .global bar
+bar:
+    jmp quux
+"#);
+
+extern "C" {
+    fn bar();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn quux() {}