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Mark more LLVM FFI as safe

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This commit is contained in:
Oli Scherer 2025-02-24 14:38:55 +00:00
parent 3565603d25
commit 553828c6f4
5 changed files with 69 additions and 59 deletions
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95
compiler/rustc_codegen_llvm/src/asm.rs
View file

@ -482,12 +482,13 @@ pub(crate) fn inline_asm_call<'ll>(
debug!("Asm Output Type: {:?}", output);
let fty = bx.cx.type_func(&argtys, output);
unsafe {
// Ask LLVM to verify that the constraints are well-formed.
let constraints_ok = llvm::LLVMRustInlineAsmVerify(fty, cons.as_c_char_ptr(), cons.len());
debug!("constraint verification result: {:?}", constraints_ok);
if constraints_ok {
let v = llvm::LLVMRustInlineAsm(
// Ask LLVM to verify that the constraints are well-formed.
let constraints_ok =
unsafe { llvm::LLVMRustInlineAsmVerify(fty, cons.as_c_char_ptr(), cons.len()) };
debug!("constraint verification result: {:?}", constraints_ok);
if constraints_ok {
let v = unsafe {
llvm::LLVMRustInlineAsm(
fty,
asm.as_c_char_ptr(),
asm.len(),
@ -497,50 +498,50 @@ pub(crate) fn inline_asm_call<'ll>(
alignstack,
dia,
can_throw,
);
)
};
let call = if !labels.is_empty() {
assert!(catch_funclet.is_none());
bx.callbr(fty, None, None, v, inputs, dest.unwrap(), labels, None, None)
} else if let Some((catch, funclet)) = catch_funclet {
bx.invoke(fty, None, None, v, inputs, dest.unwrap(), catch, funclet, None)
} else {
bx.call(fty, None, None, v, inputs, None, None)
};
// Store mark in a metadata node so we can map LLVM errors
// back to source locations. See #17552.
let key = "srcloc";
let kind = bx.get_md_kind_id(key);
// `srcloc` contains one 64-bit integer for each line of assembly code,
// where the lower 32 bits hold the lo byte position and the upper 32 bits
// hold the hi byte position.
let mut srcloc = vec![];
if dia == llvm::AsmDialect::Intel && line_spans.len() > 1 {
// LLVM inserts an extra line to add the ".intel_syntax", so add
// a dummy srcloc entry for it.
//
// Don't do this if we only have 1 line span since that may be
// due to the asm template string coming from a macro. LLVM will
// default to the first srcloc for lines that don't have an
// associated srcloc.
srcloc.push(llvm::LLVMValueAsMetadata(bx.const_u64(0)));
}
srcloc.extend(line_spans.iter().map(|span| {
llvm::LLVMValueAsMetadata(bx.const_u64(
u64::from(span.lo().to_u32()) | (u64::from(span.hi().to_u32()) << 32),
))
}));
let md = llvm::LLVMMDNodeInContext2(bx.llcx, srcloc.as_ptr(), srcloc.len());
let md = bx.get_metadata_value(md);
llvm::LLVMSetMetadata(call, kind, md);
Some(call)
let call = if !labels.is_empty() {
assert!(catch_funclet.is_none());
bx.callbr(fty, None, None, v, inputs, dest.unwrap(), labels, None, None)
} else if let Some((catch, funclet)) = catch_funclet {
bx.invoke(fty, None, None, v, inputs, dest.unwrap(), catch, funclet, None)
} else {
// LLVM has detected an issue with our constraints, bail out
None
bx.call(fty, None, None, v, inputs, None, None)
};
// Store mark in a metadata node so we can map LLVM errors
// back to source locations. See #17552.
let key = "srcloc";
let kind = bx.get_md_kind_id(key);
// `srcloc` contains one 64-bit integer for each line of assembly code,
// where the lower 32 bits hold the lo byte position and the upper 32 bits
// hold the hi byte position.
let mut srcloc = vec![];
if dia == llvm::AsmDialect::Intel && line_spans.len() > 1 {
// LLVM inserts an extra line to add the ".intel_syntax", so add
// a dummy srcloc entry for it.
//
// Don't do this if we only have 1 line span since that may be
// due to the asm template string coming from a macro. LLVM will
// default to the first srcloc for lines that don't have an
// associated srcloc.
srcloc.push(llvm::LLVMValueAsMetadata(bx.const_u64(0)));
}
srcloc.extend(line_spans.iter().map(|span| {
llvm::LLVMValueAsMetadata(
bx.const_u64(u64::from(span.lo().to_u32()) | (u64::from(span.hi().to_u32()) << 32)),
)
}));
let md = unsafe { llvm::LLVMMDNodeInContext2(bx.llcx, srcloc.as_ptr(), srcloc.len()) };
let md = bx.get_metadata_value(md);
llvm::LLVMSetMetadata(call, kind, md);
Some(call)
} else {
// LLVM has detected an issue with our constraints, bail out
None
}
}

4
compiler/rustc_codegen_llvm/src/builder.rs
View file

@ -311,8 +311,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
// This function handles switch instructions with more than 2 targets and it needs to
// emit branch weights metadata instead of using the intrinsic.
// The values 1 and 2000 are the same as the values used by the `llvm.expect` intrinsic.
let cold_weight = unsafe { llvm::LLVMValueAsMetadata(self.cx.const_u32(1)) };
let hot_weight = unsafe { llvm::LLVMValueAsMetadata(self.cx.const_u32(2000)) };
let cold_weight = llvm::LLVMValueAsMetadata(self.cx.const_u32(1));
let hot_weight = llvm::LLVMValueAsMetadata(self.cx.const_u32(2000));
let weight =
|is_cold: bool| -> &Metadata { if is_cold { cold_weight } else { hot_weight } };

10
compiler/rustc_codegen_llvm/src/context.rs
View file

@ -34,7 +34,7 @@ use crate::back::write::to_llvm_code_model;
use crate::callee::get_fn;
use crate::common::AsCCharPtr;
use crate::debuginfo::metadata::apply_vcall_visibility_metadata;
use crate::llvm::{Metadata, MetadataType};
use crate::llvm::Metadata;
use crate::type_::Type;
use crate::value::Value;
use crate::{attributes, coverageinfo, debuginfo, llvm, llvm_util};
@ -664,7 +664,7 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
unsafe { llvm::LLVMGetNamedFunction((**self).borrow().llmod, name.as_ptr()) }
}
pub(crate) fn get_md_kind_id(&self, name: &str) -> u32 {
pub(crate) fn get_md_kind_id(&self, name: &str) -> llvm::MetadataKindId {
unsafe {
llvm::LLVMGetMDKindIDInContext(
self.llcx(),
@ -1228,13 +1228,11 @@ impl<'ll, CX: Borrow<SCx<'ll>>> GenericCx<'ll, CX> {
pub(crate) fn set_metadata<'a>(
&self,
val: &'a Value,
kind_id: MetadataType,
kind_id: impl Into<llvm::MetadataKindId>,
md: &'ll Metadata,
) {
let node = self.get_metadata_value(md);
unsafe {
llvm::LLVMSetMetadata(val, kind_id as c_uint, node);
}
llvm::LLVMSetMetadata(val, kind_id.into(), node);
}
}

3
compiler/rustc_codegen_llvm/src/llvm/enzyme_ffi.rs
View file

@ -3,13 +3,14 @@
use libc::{c_char, c_uint};
use super::MetadataKindId;
use super::ffi::{BasicBlock, Metadata, Module, Type, Value};
use crate::llvm::Bool;
#[link(name = "llvm-wrapper", kind = "static")]
unsafe extern "C" {
// Enzyme
pub(crate) fn LLVMRustHasMetadata(I: &Value, KindID: c_uint) -> bool;
pub(crate) safe fn LLVMRustHasMetadata(I: &Value, KindID: MetadataKindId) -> bool;
pub(crate) fn LLVMRustEraseInstUntilInclusive(BB: &BasicBlock, I: &Value);
pub(crate) fn LLVMRustGetLastInstruction<'a>(BB: &BasicBlock) -> Option<&'a Value>;
pub(crate) fn LLVMRustDIGetInstMetadata(I: &Value) -> Option<&Metadata>;

16
compiler/rustc_codegen_llvm/src/llvm/ffi.rs
View file

@ -976,6 +976,16 @@ pub type SelfProfileAfterPassCallback = unsafe extern "C" fn(*mut c_void);
pub type GetSymbolsCallback = unsafe extern "C" fn(*mut c_void, *const c_char) -> *mut c_void;
pub type GetSymbolsErrorCallback = unsafe extern "C" fn(*const c_char) -> *mut c_void;
#[derive(Copy, Clone)]
#[repr(transparent)]
pub struct MetadataKindId(c_uint);
impl From<MetadataType> for MetadataKindId {
fn from(value: MetadataType) -> Self {
Self(value as c_uint)
}
}
unsafe extern "C" {
// Create and destroy contexts.
pub(crate) fn LLVMContextDispose(C: &'static mut Context);
@ -983,7 +993,7 @@ unsafe extern "C" {
C: &Context,
Name: *const c_char,
SLen: c_uint,
) -> c_uint;
) -> MetadataKindId;
// Create modules.
pub(crate) fn LLVMModuleCreateWithNameInContext(
@ -1051,9 +1061,9 @@ unsafe extern "C" {
pub(crate) fn LLVMGetValueName2(Val: &Value, Length: *mut size_t) -> *const c_char;
pub(crate) fn LLVMSetValueName2(Val: &Value, Name: *const c_char, NameLen: size_t);
pub(crate) fn LLVMReplaceAllUsesWith<'a>(OldVal: &'a Value, NewVal: &'a Value);
pub(crate) fn LLVMSetMetadata<'a>(Val: &'a Value, KindID: c_uint, Node: &'a Value);
pub(crate) safe fn LLVMSetMetadata<'a>(Val: &'a Value, KindID: MetadataKindId, Node: &'a Value);
pub(crate) fn LLVMGlobalSetMetadata<'a>(Val: &'a Value, KindID: c_uint, Metadata: &'a Metadata);
pub(crate) fn LLVMValueAsMetadata(Node: &Value) -> &Metadata;
pub(crate) safe fn LLVMValueAsMetadata(Node: &Value) -> &Metadata;
// Operations on constants of any type
pub(crate) fn LLVMConstNull(Ty: &Type) -> &Value;