src/librustc_codegen_llvm/asm.rs

   1 use crate::llvm;
   2 use crate::context::CodegenCx;
   3 use crate::type_of::LayoutLlvmExt;
   4 use crate::builder::Builder;
   5 use crate::value::Value;
   6
   7 use rustc::hir;
   8 use rustc_codegen_ssa::traits::*;
   9 use rustc_codegen_ssa::mir::place::PlaceRef;
  10 use rustc_codegen_ssa::mir::operand::OperandValue;
  11 use syntax_pos::Span;
  12
  13 use std::ffi::{CStr, CString};
  14 use libc::{c_uint, c_char};
  15 use log::debug;
  16
  17 impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
  18     fn codegen_inline_asm(
  19         &mut self,
  20         ia: &hir::InlineAsmInner,
  21         outputs: Vec<PlaceRef<'tcx, &'ll Value>>,
  22         mut inputs: Vec<&'ll Value>,
  23         span: Span,
  24     ) -> bool {
  25         let mut ext_constraints = vec![];
  26         let mut output_types = vec![];
  27
  28         // Prepare the output operands
  29         let mut indirect_outputs = vec![];
  30         for (i, (out, &place)) in ia.outputs.iter().zip(&outputs).enumerate() {
  31             if out.is_rw {
  32                 inputs.push(self.load_operand(place).immediate());
  33                 ext_constraints.push(i.to_string());
  34             }
  35             if out.is_indirect {
  36                 indirect_outputs.push(self.load_operand(place).immediate());
  37             } else {
  38                 output_types.push(place.layout.llvm_type(self.cx()));
  39             }
  40         }
  41         if !indirect_outputs.is_empty() {
  42             indirect_outputs.extend_from_slice(&inputs);
  43             inputs = indirect_outputs;
  44         }
  45
  46         let clobbers = ia.clobbers.iter()
  47                                   .map(|s| format!("~{{{}}}", &s));
  48
  49         // Default per-arch clobbers
  50         // Basically what clang does
  51         let arch_clobbers = match &self.sess().target.target.arch[..] {
  52             "x86" | "x86_64"  => vec!["~{dirflag}", "~{fpsr}", "~{flags}"],
  53             "mips" | "mips64" => vec!["~{$1}"],
  54             _                 => Vec::new()
  55         };
  56
  57         let all_constraints =
  58             ia.outputs.iter().map(|out| out.constraint.to_string())
  59               .chain(ia.inputs.iter().map(|s| s.to_string()))
  60               .chain(ext_constraints)
  61               .chain(clobbers)
  62               .chain(arch_clobbers.iter().map(|s| s.to_string()))
  63               .collect::<Vec<String>>().join(",");
  64
  65         debug!("Asm Constraints: {}", &all_constraints);
  66
  67         // Depending on how many outputs we have, the return type is different
  68         let num_outputs = output_types.len();
  69         let output_type = match num_outputs {
  70             0 => self.type_void(),
  71             1 => output_types[0],
  72             _ => self.type_struct(&output_types, false)
  73         };
  74
  75         let asm = CString::new(ia.asm.as_str().as_bytes()).unwrap();
  76         let constraint_cstr = CString::new(all_constraints).unwrap();
  77         let r = inline_asm_call(
  78             self,
  79             &asm,
  80             &constraint_cstr,
  81             &inputs,
  82             output_type,
  83             ia.volatile,
  84             ia.alignstack,
  85             ia.dialect
  86         );
  87         if r.is_none() {
  88             return false;
  89         }
  90         let r = r.unwrap();
  91
  92         // Again, based on how many outputs we have
  93         let outputs = ia.outputs.iter().zip(&outputs).filter(|&(ref o, _)| !o.is_indirect);
  94         for (i, (_, &place)) in outputs.enumerate() {
  95             let v = if num_outputs == 1 { r } else { self.extract_value(r, i as u64) };
  96             OperandValue::Immediate(v).store(self, place);
  97         }
  98
  99         // Store mark in a metadata node so we can map LLVM errors
 100         // back to source locations.  See #17552.
 101         unsafe {
 102             let key = "srcloc";
 103             let kind = llvm::LLVMGetMDKindIDInContext(self.llcx,
 104                 key.as_ptr() as *const c_char, key.len() as c_uint);
 105
 106             let val: &'ll Value = self.const_i32(span.ctxt().outer_expn().as_u32() as i32);
 107
 108             llvm::LLVMSetMetadata(r, kind,
 109                 llvm::LLVMMDNodeInContext(self.llcx, &val, 1));
 110         }
 111
 112         true
 113     }
 114 }
 115
 116 impl AsmMethods for CodegenCx<'ll, 'tcx> {
 117     fn codegen_global_asm(&self, ga: &hir::GlobalAsm) {
 118         let asm = CString::new(ga.asm.as_str().as_bytes()).unwrap();
 119         unsafe {
 120             llvm::LLVMRustAppendModuleInlineAsm(self.llmod, asm.as_ptr());
 121         }
 122     }
 123 }
 124
 125 fn inline_asm_call(
 126     bx: &mut Builder<'a, 'll, 'tcx>,
 127     asm: &CStr,
 128     cons: &CStr,
 129     inputs: &[&'ll Value],
 130     output: &'ll llvm::Type,
 131     volatile: bool,
 132     alignstack: bool,
 133     dia: ::syntax::ast::AsmDialect,
 134 ) -> Option<&'ll Value> {
 135     let volatile = if volatile { llvm::True }
 136                     else        { llvm::False };
 137     let alignstack = if alignstack { llvm::True }
 138                         else          { llvm::False };
 139
 140     let argtys = inputs.iter().map(|v| {
 141         debug!("Asm Input Type: {:?}", *v);
 142         bx.cx.val_ty(*v)
 143     }).collect::<Vec<_>>();
 144
 145     debug!("Asm Output Type: {:?}", output);
 146     let fty = bx.cx.type_func(&argtys[..], output);
 147     unsafe {
 148         // Ask LLVM to verify that the constraints are well-formed.
 149         let constraints_ok = llvm::LLVMRustInlineAsmVerify(fty, cons.as_ptr());
 150         debug!("constraint verification result: {:?}", constraints_ok);
 151         if constraints_ok {
 152             let v = llvm::LLVMRustInlineAsm(
 153                 fty,
 154                 asm.as_ptr(),
 155                 cons.as_ptr(),
 156                 volatile,
 157                 alignstack,
 158                 llvm::AsmDialect::from_generic(dia),
 159             );
 160             Some(bx.call(v, inputs, None))
 161         } else {
 162             // LLVM has detected an issue with our constraints, bail out
 163             None
 164         }
 165     }
 166 }