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Auto merge of #113722 - bjorn3:allocator_shim_refactor, r=jackh726
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Extract a create_wrapper_function for use in allocator shim writing

This deduplicates some logic and makes it easier to follow what wrappers are produced. In the future it may allow moving the code to determine which wrappers to create to cg_ssa.
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@bors
bors committed Aug 13, 2023
2 parents 2b26bf5 + 49ae3b7 commit 644e806
Showing 1 changed file with 90 additions and 92 deletions.
182 changes: 90 additions & 92 deletions compiler/rustc_codegen_llvm/src/allocator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use rustc_middle::ty::TyCtxt;
use rustc_session::config::{DebugInfo, OomStrategy};

use crate::debuginfo;
use crate::llvm::{self, False, True};
use crate::llvm::{self, Context, False, Module, True, Type};
use crate::ModuleLlvm;

pub(crate) unsafe fn codegen(
Expand All @@ -29,7 +29,6 @@ pub(crate) unsafe fn codegen(
};
let i8 = llvm::LLVMInt8TypeInContext(llcx);
let i8p = llvm::LLVMPointerTypeInContext(llcx, 0);
let void = llvm::LLVMVoidTypeInContext(llcx);

if kind == AllocatorKind::Default {
for method in ALLOCATOR_METHODS {
Expand All @@ -54,102 +53,25 @@ pub(crate) unsafe fn codegen(
panic!("invalid allocator output")
}
};
let ty = llvm::LLVMFunctionType(
output.unwrap_or(void),
args.as_ptr(),
args.len() as c_uint,
False,
);
let name = global_fn_name(method.name);
let llfn =
llvm::LLVMRustGetOrInsertFunction(llmod, name.as_ptr().cast(), name.len(), ty);

if tcx.sess.target.default_hidden_visibility {
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
}
if tcx.sess.must_emit_unwind_tables() {
let uwtable = attributes::uwtable_attr(llcx);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
}

let callee = default_fn_name(method.name);
let callee =
llvm::LLVMRustGetOrInsertFunction(llmod, callee.as_ptr().cast(), callee.len(), ty);
llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);

let llbb = llvm::LLVMAppendBasicBlockInContext(llcx, llfn, "entry\0".as_ptr().cast());

let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
let args = args
.iter()
.enumerate()
.map(|(i, _)| llvm::LLVMGetParam(llfn, i as c_uint))
.collect::<Vec<_>>();
let ret = llvm::LLVMRustBuildCall(
llbuilder,
ty,
callee,
args.as_ptr(),
args.len() as c_uint,
[].as_ptr(),
0 as c_uint,
);
llvm::LLVMSetTailCall(ret, True);
if output.is_some() {
llvm::LLVMBuildRet(llbuilder, ret);
} else {
llvm::LLVMBuildRetVoid(llbuilder);
}
llvm::LLVMDisposeBuilder(llbuilder);
let from_name = global_fn_name(method.name);
let to_name = default_fn_name(method.name);

create_wrapper_function(tcx, llcx, llmod, &from_name, &to_name, &args, output, false);
}
}

// rust alloc error handler
let args = [usize, usize]; // size, align

let ty = llvm::LLVMFunctionType(void, args.as_ptr(), args.len() as c_uint, False);
let name = "__rust_alloc_error_handler";
let llfn = llvm::LLVMRustGetOrInsertFunction(llmod, name.as_ptr().cast(), name.len(), ty);
// -> ! DIFlagNoReturn
let no_return = llvm::AttributeKind::NoReturn.create_attr(llcx);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[no_return]);

if tcx.sess.target.default_hidden_visibility {
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
}
if tcx.sess.must_emit_unwind_tables() {
let uwtable = attributes::uwtable_attr(llcx);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
}

let callee = alloc_error_handler_name(alloc_error_handler_kind);
let callee = llvm::LLVMRustGetOrInsertFunction(llmod, callee.as_ptr().cast(), callee.len(), ty);
// -> ! DIFlagNoReturn
attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]);
llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);

let llbb = llvm::LLVMAppendBasicBlockInContext(llcx, llfn, "entry\0".as_ptr().cast());

let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
let args = args
.iter()
.enumerate()
.map(|(i, _)| llvm::LLVMGetParam(llfn, i as c_uint))
.collect::<Vec<_>>();
let ret = llvm::LLVMRustBuildCall(
llbuilder,
ty,
callee,
args.as_ptr(),
args.len() as c_uint,
[].as_ptr(),
0 as c_uint,
create_wrapper_function(
tcx,
llcx,
llmod,
"__rust_alloc_error_handler",
&alloc_error_handler_name(alloc_error_handler_kind),
&[usize, usize], // size, align
None,
true,
);
llvm::LLVMSetTailCall(ret, True);
llvm::LLVMBuildRetVoid(llbuilder);
llvm::LLVMDisposeBuilder(llbuilder);

// __rust_alloc_error_handler_should_panic
let name = OomStrategy::SYMBOL;
Expand All @@ -175,3 +97,79 @@ pub(crate) unsafe fn codegen(
dbg_cx.finalize(tcx.sess);
}
}

fn create_wrapper_function(
tcx: TyCtxt<'_>,
llcx: &Context,
llmod: &Module,
from_name: &str,
to_name: &str,
args: &[&Type],
output: Option<&Type>,
no_return: bool,
) {
unsafe {
let ty = llvm::LLVMFunctionType(
output.unwrap_or_else(|| llvm::LLVMVoidTypeInContext(llcx)),
args.as_ptr(),
args.len() as c_uint,
False,
);
let llfn = llvm::LLVMRustGetOrInsertFunction(
llmod,
from_name.as_ptr().cast(),
from_name.len(),
ty,
);
let no_return = if no_return {
// -> ! DIFlagNoReturn
let no_return = llvm::AttributeKind::NoReturn.create_attr(llcx);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[no_return]);
Some(no_return)
} else {
None
};

if tcx.sess.target.default_hidden_visibility {
llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
}
if tcx.sess.must_emit_unwind_tables() {
let uwtable = attributes::uwtable_attr(llcx);
attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &[uwtable]);
}

let callee =
llvm::LLVMRustGetOrInsertFunction(llmod, to_name.as_ptr().cast(), to_name.len(), ty);
if let Some(no_return) = no_return {
// -> ! DIFlagNoReturn
attributes::apply_to_llfn(callee, llvm::AttributePlace::Function, &[no_return]);
}
llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);

let llbb = llvm::LLVMAppendBasicBlockInContext(llcx, llfn, "entry\0".as_ptr().cast());

let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
let args = args
.iter()
.enumerate()
.map(|(i, _)| llvm::LLVMGetParam(llfn, i as c_uint))
.collect::<Vec<_>>();
let ret = llvm::LLVMRustBuildCall(
llbuilder,
ty,
callee,
args.as_ptr(),
args.len() as c_uint,
[].as_ptr(),
0 as c_uint,
);
llvm::LLVMSetTailCall(ret, True);
if output.is_some() {
llvm::LLVMBuildRet(llbuilder, ret);
} else {
llvm::LLVMBuildRetVoid(llbuilder);
}
llvm::LLVMDisposeBuilder(llbuilder);
}
}

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