src/librustc_codegen_llvm/allocator.rs

   1 use std::ffi::CString;
   2
   3 use crate::attributes;
   4 use libc::c_uint;
   5 use rustc::ty::TyCtxt;
   6 use syntax::expand::allocator::{AllocatorKind, AllocatorTy, ALLOCATOR_METHODS};
   7 use rustc::bug;
   8
   9 use crate::ModuleLlvm;
  10 use crate::llvm::{self, False, True};
  11
  12 pub(crate) unsafe fn codegen(tcx: TyCtxt<'_>, mods: &mut ModuleLlvm, kind: AllocatorKind) {
  13     let llcx = &*mods.llcx;
  14     let llmod = mods.llmod();
  15     let usize = match &tcx.sess.target.target.target_pointer_width[..] {
  16         "16" => llvm::LLVMInt16TypeInContext(llcx),
  17         "32" => llvm::LLVMInt32TypeInContext(llcx),
  18         "64" => llvm::LLVMInt64TypeInContext(llcx),
  19         tws => bug!("Unsupported target word size for int: {}", tws),
  20     };
  21     let i8 = llvm::LLVMInt8TypeInContext(llcx);
  22     let i8p = llvm::LLVMPointerType(i8, 0);
  23     let void = llvm::LLVMVoidTypeInContext(llcx);
  24
  25     for method in ALLOCATOR_METHODS {
  26         let mut args = Vec::with_capacity(method.inputs.len());
  27         for ty in method.inputs.iter() {
  28             match *ty {
  29                 AllocatorTy::Layout => {
  30                     args.push(usize); // size
  31                     args.push(usize); // align
  32                 }
  33                 AllocatorTy::Ptr => args.push(i8p),
  34                 AllocatorTy::Usize => args.push(usize),
  35
  36                 AllocatorTy::ResultPtr |
  37                 AllocatorTy::Unit => panic!("invalid allocator arg"),
  38             }
  39         }
  40         let output = match method.output {
  41             AllocatorTy::ResultPtr => Some(i8p),
  42             AllocatorTy::Unit => None,
  43
  44             AllocatorTy::Layout |
  45             AllocatorTy::Usize |
  46             AllocatorTy::Ptr => panic!("invalid allocator output"),
  47         };
  48         let ty = llvm::LLVMFunctionType(output.unwrap_or(void),
  49                                         args.as_ptr(),
  50                                         args.len() as c_uint,
  51                                         False);
  52         let name = CString::new(format!("__rust_{}", method.name)).unwrap();
  53         let llfn = llvm::LLVMRustGetOrInsertFunction(llmod,
  54                                                      name.as_ptr(),
  55                                                      ty);
  56
  57         if tcx.sess.target.target.options.default_hidden_visibility {
  58             llvm::LLVMRustSetVisibility(llfn, llvm::Visibility::Hidden);
  59         }
  60         if tcx.sess.target.target.options.requires_uwtable {
  61             attributes::emit_uwtable(llfn, true);
  62         }
  63
  64         let callee = CString::new(kind.fn_name(method.name)).unwrap();
  65         let callee = llvm::LLVMRustGetOrInsertFunction(llmod,
  66                                                        callee.as_ptr(),
  67                                                        ty);
  68         llvm::LLVMRustSetVisibility(callee, llvm::Visibility::Hidden);
  69
  70         let llbb = llvm::LLVMAppendBasicBlockInContext(llcx,
  71                                                        llfn,
  72                                                        "entry\0".as_ptr().cast());
  73
  74         let llbuilder = llvm::LLVMCreateBuilderInContext(llcx);
  75         llvm::LLVMPositionBuilderAtEnd(llbuilder, llbb);
  76         let args = args.iter().enumerate().map(|(i, _)| {
  77             llvm::LLVMGetParam(llfn, i as c_uint)
  78         }).collect::<Vec<_>>();
  79         let ret = llvm::LLVMRustBuildCall(llbuilder,
  80                                           callee,
  81                                           args.as_ptr(),
  82                                           args.len() as c_uint,
  83                                           None,
  84                                           "\0".as_ptr().cast());
  85         llvm::LLVMSetTailCall(ret, True);
  86         if output.is_some() {
  87             llvm::LLVMBuildRet(llbuilder, ret);
  88         } else {
  89             llvm::LLVMBuildRetVoid(llbuilder);
  90         }
  91         llvm::LLVMDisposeBuilder(llbuilder);
  92     }
  93 }