compiler/rustc_codegen_llvm/src/allocator.rs

   1 use crate::attributes;
   2 use libc::c_uint;
   3 use rustc_ast::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
   4 use rustc_middle::bug;
   5 use rustc_middle::ty::TyCtxt;
   6
   7 use crate::llvm::{self, False, True};
   8 use crate::ModuleLlvm;
   9
  10 pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut ModuleLlvm, kind: AllocatorKind) {
  11     let llcx = &*mods.llcx;
  12     let llmod = mods.llmod();
  13     let usize = match &tcx.sess.target.target.target_pointer_width[..] {
  14         "16" => llvm::LLVMInt16TypeInContext(llcx),
  15         "32" => llvm::LLVMInt32TypeInContext(llcx),
  16         "64" => llvm::LLVMInt64TypeInContext(llcx),
  17         tws => bug!("Unsupported target word size for int: {}", tws),
  18     };
  19     let i8 = llvm::LLVMInt8TypeInContext(llcx);
  20     let i8p = llvm::LLVMPointerType(i8, 0);
  21     let void = llvm::LLVMVoidTypeInContext(llcx);
  22
  23     for method in ALLOCATOR_METHODS {
  24         let mut args = Vec::with_capacity(method.inputs.len());
  25         for ty in method.inputs.iter() {
  26             match *ty {
  27                 AllocatorTy::Layout => {
  28                     args.push(usize); // size
  29                     args.push(usize); // align
  30                 }
  31                 AllocatorTy::Ptr => args.push(i8p),
  32                 AllocatorTy::Usize => args.push(usize),
  33
  34                 AllocatorTy::ResultPtr | AllocatorTy::Unit => panic!("invalid allocator arg"),
  35             }
  36         }
  37         let output = match method.output {
  38             AllocatorTy::ResultPtr => Some(i8p),
  39             AllocatorTy::Unit => None,
  40
  41             AllocatorTy::Layout | AllocatorTy::Usize | AllocatorTy::Ptr => {
  42                 panic!("invalid allocator output")
  43             }
  44         };
  45         let ty = llvm::LLVMFunctionType(
  46             output.unwrap_or(void),
  47             args.as_ptr(),
  48             args.len() as c_uint,
  49             False,
  50         );
  51         let name = format!("__rust_{}", method.name);
  52         let llfn = llvm::LLVMRustGetOrInsertFunction(llmod, name.as_ptr().cast(), name.len(), ty);
  53
  54         if tcx.sess.target.target.options.default_hidden_visibility {
  55             llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
  56         }
  57         if tcx.sess.must_emit_unwind_tables() {
  58             attributes::emit_uwtable(llfn, true);
  59         }
  60
  61         let callee = kind.fn_name(method.name);
  62         let callee =
  63             llvm::LLVMRustGetOrInsertFunction(llmod, callee.as_ptr().cast(), callee.len(), ty);
  64         llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);
  65
  66         let llbb = llvm::LLVMAppendBasicBlockInContext(llcx, llfn, "entry\0".as_ptr().cast());
  67
  68         let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
  69         llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
  70         let args = args
  71             .iter()
  72             .enumerate()
  73             .map(|(i, _)| llvm::LLVMGetParam(llfn, i as c_uint))
  74             .collect::<Vec<_>>();
  75         let ret =
  76             llvm::LLVMRustBuildCall(llbuilder, callee, args.as_ptr(), args.len() as c_uint, None);
  77         llvm::LLVMSetTailCall(ret, True);
  78         if output.is_some() {
  79             llvm::LLVMBuildRet(llbuilder, ret);
  80         } else {
  81             llvm::LLVMBuildRetVoid(llbuilder);
  82         }
  83         llvm::LLVMDisposeBuilder(llbuilder);
  84     }
  85 }