From 64a3bd84d83a6138b6e7db82a53199246f292e53 Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Fri, 21 Jun 2024 14:01:15 -0500
Subject: [PATCH 1/3] Always preserve user-written comments in assembly
---
compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 3 ++-
tests/assembly/asm-comments.rs | 12 ++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 tests/assembly/asm-comments.rs
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index c4cfc0b6dc6a1..a868c56c4e625 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -436,7 +436,8 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
Options.FunctionSections = FunctionSections;
Options.UniqueSectionNames = UniqueSectionNames;
Options.MCOptions.AsmVerbose = AsmComments;
- Options.MCOptions.PreserveAsmComments = AsmComments;
+ // Always preserve comments that were written by the user
+ Options.MCOptions.PreserveAsmComments = true;
Options.MCOptions.ABIName = ABIStr;
if (SplitDwarfFile) {
Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
diff --git a/tests/assembly/asm-comments.rs b/tests/assembly/asm-comments.rs
new file mode 100644
index 0000000000000..557009975ddc9
--- /dev/null
+++ b/tests/assembly/asm-comments.rs
@@ -0,0 +1,12 @@
+//@ assembly-output: emit-asm
+//@ only-x86_64
+// Check that comments in assembly get passed
+
+#![crate_type = "lib"]
+
+// CHECK-LABEL: test_comments:
+#[no_mangle]
+pub fn test_comments() {
+ // CHECK: example comment
+ unsafe { core::arch::asm!("nop // example comment") };
+}
From c15a698f567356cea22e79686c2883f3557bae0b Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Fri, 21 Jun 2024 14:08:49 -0500
Subject: [PATCH 2/3] Rename the `asm-comments` compiler flag to `verbose-asm`
Since this codegen flag now only controls LLVM-generated comments rather than
all assembly comments, make the name more accurate (and also match Clang).
---
compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs | 4 ++--
compiler/rustc_codegen_llvm/src/back/write.rs | 4 ++--
compiler/rustc_codegen_llvm/src/llvm/ffi.rs | 2 +-
compiler/rustc_interface/src/tests.rs | 2 +-
compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp | 4 ++--
compiler/rustc_session/src/options.rs | 4 ++--
6 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs b/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
index 28a88dd2efea0..b72636a62248e 100644
--- a/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
+++ b/compiler/rustc_codegen_llvm/src/back/owned_target_machine.rs
@@ -32,7 +32,7 @@ impl OwnedTargetMachine {
unique_section_names: bool,
trap_unreachable: bool,
singletree: bool,
- asm_comments: bool,
+ verbose_asm: bool,
emit_stack_size_section: bool,
relax_elf_relocations: bool,
use_init_array: bool,
@@ -64,7 +64,7 @@ impl OwnedTargetMachine {
unique_section_names,
trap_unreachable,
singletree,
- asm_comments,
+ verbose_asm,
emit_stack_size_section,
relax_elf_relocations,
use_init_array,
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 5e481eb98f55f..2fda19bf0c914 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -214,7 +214,7 @@ pub fn target_machine_factory(
sess.opts.unstable_opts.trap_unreachable.unwrap_or(sess.target.trap_unreachable);
let emit_stack_size_section = sess.opts.unstable_opts.emit_stack_sizes;
- let asm_comments = sess.opts.unstable_opts.asm_comments;
+ let verbose_asm = sess.opts.unstable_opts.verbose_asm;
let relax_elf_relocations =
sess.opts.unstable_opts.relax_elf_relocations.unwrap_or(sess.target.relax_elf_relocations);
@@ -289,7 +289,7 @@ pub fn target_machine_factory(
funique_section_names,
trap_unreachable,
singlethread,
- asm_comments,
+ verbose_asm,
emit_stack_size_section,
relax_elf_relocations,
use_init_array,
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 132e1f9e8fd93..08e9e312827ce 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -2185,7 +2185,7 @@ extern "C" {
UniqueSectionNames: bool,
TrapUnreachable: bool,
Singlethread: bool,
- AsmComments: bool,
+ VerboseAsm: bool,
EmitStackSizeSection: bool,
RelaxELFRelocations: bool,
UseInitArray: bool,
diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs
index 9bd67a1154b7d..e2ba75dfd1902 100644
--- a/compiler/rustc_interface/src/tests.rs
+++ b/compiler/rustc_interface/src/tests.rs
@@ -757,7 +757,6 @@ fn test_unstable_options_tracking_hash() {
// tidy-alphabetical-start
tracked!(allow_features, Some(vec![String::from("lang_items")]));
tracked!(always_encode_mir, true);
- tracked!(asm_comments, true);
tracked!(assume_incomplete_release, true);
tracked!(binary_dep_depinfo, true);
tracked!(box_noalias, false);
@@ -862,6 +861,7 @@ fn test_unstable_options_tracking_hash() {
tracked!(uninit_const_chunk_threshold, 123);
tracked!(unleash_the_miri_inside_of_you, true);
tracked!(use_ctors_section, Some(true));
+ tracked!(verbose_asm, true);
tracked!(verify_llvm_ir, true);
tracked!(virtual_function_elimination, true);
tracked!(wasi_exec_model, Some(WasiExecModel::Reactor));
diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
index a868c56c4e625..283c4fbbb7cf4 100644
--- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp
@@ -407,7 +407,7 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
const char *ABIStr, LLVMRustCodeModel RustCM, LLVMRustRelocModel RustReloc,
LLVMRustCodeGenOptLevel RustOptLevel, bool UseSoftFloat,
bool FunctionSections, bool DataSections, bool UniqueSectionNames,
- bool TrapUnreachable, bool Singlethread, bool AsmComments,
+ bool TrapUnreachable, bool Singlethread, bool VerboseAsm,
bool EmitStackSizeSection, bool RelaxELFRelocations, bool UseInitArray,
const char *SplitDwarfFile, const char *OutputObjFile,
const char *DebugInfoCompression, bool UseEmulatedTls,
@@ -435,7 +435,7 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
Options.DataSections = DataSections;
Options.FunctionSections = FunctionSections;
Options.UniqueSectionNames = UniqueSectionNames;
- Options.MCOptions.AsmVerbose = AsmComments;
+ Options.MCOptions.AsmVerbose = VerboseAsm;
// Always preserve comments that were written by the user
Options.MCOptions.PreserveAsmComments = true;
Options.MCOptions.ABIName = ABIStr;
diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs
index 2e4421d50e313..7421cae65e4f8 100644
--- a/compiler/rustc_session/src/options.rs
+++ b/compiler/rustc_session/src/options.rs
@@ -1630,8 +1630,6 @@ options! {
"only allow the listed language features to be enabled in code (comma separated)"),
always_encode_mir: bool = (false, parse_bool, [TRACKED],
"encode MIR of all functions into the crate metadata (default: no)"),
- asm_comments: bool = (false, parse_bool, [TRACKED],
- "generate comments into the assembly (may change behavior) (default: no)"),
assert_incr_state: Option<String> = (None, parse_opt_string, [UNTRACKED],
"assert that the incremental cache is in given state: \
either `loaded` or `not-loaded`."),
@@ -2107,6 +2105,8 @@ written to standard error output)"),
"Generate sync unwind tables instead of async unwind tables (default: no)"),
validate_mir: bool = (false, parse_bool, [UNTRACKED],
"validate MIR after each transformation"),
+ verbose_asm: bool = (false, parse_bool, [TRACKED],
+ "add descriptive comments from LLVM to the assembly (may change behavior) (default: no)"),
#[rustc_lint_opt_deny_field_access("use `Session::verbose_internals` instead of this field")]
verbose_internals: bool = (false, parse_bool, [TRACKED_NO_CRATE_HASH],
"in general, enable more debug printouts (default: no)"),
From 1a6893e14b7d08aee18acf82b9a08e1ba8534d7b Mon Sep 17 00:00:00 2001
From: Trevor Gross <tmgross@umich.edu>
Date: Fri, 21 Jun 2024 14:17:47 -0500
Subject: [PATCH 3/3] Add documentation for -Zverbose-asm
---
.../src/compiler-flags/verbose-asm.md | 70 +++++++++++++++++++
1 file changed, 70 insertions(+)
create mode 100644 src/doc/unstable-book/src/compiler-flags/verbose-asm.md
diff --git a/src/doc/unstable-book/src/compiler-flags/verbose-asm.md b/src/doc/unstable-book/src/compiler-flags/verbose-asm.md
new file mode 100644
index 0000000000000..84eb90a14cf53
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags/verbose-asm.md
@@ -0,0 +1,70 @@
+# `verbose-asm`
+
+The tracking issue for this feature is: [#126802](https://github.com/rust-lang/rust/issues/126802).
+
+------------------------
+
+This enables passing `-Zverbose-asm` to get contextual comments added by LLVM.
+
+Sample code:
+
+```rust
+#[no_mangle]
+pub fn foo(a: i32, b: i32) -> i32 {
+ a + b
+}
+```
+
+Default output:
+
+```asm
+foo:
+ push rax
+ add edi, esi
+ mov dword ptr [rsp + 4], edi
+ seto al
+ jo .LBB0_2
+ mov eax, dword ptr [rsp + 4]
+ pop rcx
+ ret
+.LBB0_2:
+ lea rdi, [rip + .L__unnamed_1]
+ mov rax, qword ptr [rip + core::panicking::panic_const::panic_const_add_overflow::h9c85248fe0d735b2@GOTPCREL]
+ call rax
+
+.L__unnamed_2:
+ .ascii "/app/example.rs"
+
+.L__unnamed_1:
+ .quad .L__unnamed_2
+ .asciz "\017\000\000\000\000\000\000\000\004\000\000\000\005\000\000"
+```
+
+With `-Zverbose-asm`:
+
+```asm
+foo: # @foo
+# %bb.0:
+ push rax
+ add edi, esi
+ mov dword ptr [rsp + 4], edi # 4-byte Spill
+ seto al
+ jo .LBB0_2
+# %bb.1:
+ mov eax, dword ptr [rsp + 4] # 4-byte Reload
+ pop rcx
+ ret
+.LBB0_2:
+ lea rdi, [rip + .L__unnamed_1]
+ mov rax, qword ptr [rip + core::panicking::panic_const::panic_const_add_overflow::h9c85248fe0d735b2@GOTPCREL]
+ call rax
+ # -- End function
+.L__unnamed_2:
+ .ascii "/app/example.rs"
+
+.L__unnamed_1:
+ .quad .L__unnamed_2
+ .asciz "\017\000\000\000\000\000\000\000\004\000\000\000\005\000\000"
+
+ # DW_AT_external
+```