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