compiler/rustc_codegen_ssa/src/mir/statement.rs

   1 use rustc_middle::mir;
   2
   3 use super::FunctionCx;
   4 use super::LocalRef;
   5 use crate::traits::BuilderMethods;
   6 use crate::traits::*;
   7
   8 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
   9     #[instrument(level = "debug", skip(self, bx))]
  10     pub fn codegen_statement(&mut self, mut bx: Bx, statement: &mir::Statement<'tcx>) -> Bx {
  11         self.set_debug_loc(&mut bx, statement.source_info);
  12         match statement.kind {
  13             mir::StatementKind::Assign(box (ref place, ref rvalue)) => {
  14                 if let Some(index) = place.as_local() {
  15                     match self.locals[index] {
  16                         LocalRef::Place(cg_dest) => self.codegen_rvalue(bx, cg_dest, rvalue),
  17                         LocalRef::UnsizedPlace(cg_indirect_dest) => {
  18                             self.codegen_rvalue_unsized(bx, cg_indirect_dest, rvalue)
  19                         }
  20                         LocalRef::Operand(None) => {
  21                             let (mut bx, operand) = self.codegen_rvalue_operand(bx, rvalue);
  22                             self.locals[index] = LocalRef::Operand(Some(operand));
  23                             self.debug_introduce_local(&mut bx, index);
  24                             bx
  25                         }
  26                         LocalRef::Operand(Some(op)) => {
  27                             if !op.layout.is_zst() {
  28                                 span_bug!(
  29                                     statement.source_info.span,
  30                                     "operand {:?} already assigned",
  31                                     rvalue
  32                                 );
  33                             }
  34
  35                             // If the type is zero-sized, it's already been set here,
  36                             // but we still need to make sure we codegen the operand
  37                             self.codegen_rvalue_operand(bx, rvalue).0
  38                         }
  39                     }
  40                 } else {
  41                     let cg_dest = self.codegen_place(&mut bx, place.as_ref());
  42                     self.codegen_rvalue(bx, cg_dest, rvalue)
  43                 }
  44             }
  45             mir::StatementKind::SetDiscriminant { box ref place, variant_index } => {
  46                 self.codegen_place(&mut bx, place.as_ref())
  47                     .codegen_set_discr(&mut bx, variant_index);
  48                 bx
  49             }
  50             mir::StatementKind::Deinit(..) => {
  51                 // For now, don't codegen this to anything. In the future it may be worth
  52                 // experimenting with what kind of information we can emit to LLVM without hurting
  53                 // perf here
  54                 bx
  55             }
  56             mir::StatementKind::StorageLive(local) => {
  57                 if let LocalRef::Place(cg_place) = self.locals[local] {
  58                     cg_place.storage_live(&mut bx);
  59                 } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
  60                     cg_indirect_place.storage_live(&mut bx);
  61                 }
  62                 bx
  63             }
  64             mir::StatementKind::StorageDead(local) => {
  65                 if let LocalRef::Place(cg_place) = self.locals[local] {
  66                     cg_place.storage_dead(&mut bx);
  67                 } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
  68                     cg_indirect_place.storage_dead(&mut bx);
  69                 }
  70                 bx
  71             }
  72             mir::StatementKind::Coverage(box ref coverage) => {
  73                 self.codegen_coverage(&mut bx, coverage.clone(), statement.source_info.scope);
  74                 bx
  75             }
  76             mir::StatementKind::CopyNonOverlapping(box mir::CopyNonOverlapping {
  77                 ref src,
  78                 ref dst,
  79                 ref count,
  80             }) => {
  81                 let dst_val = self.codegen_operand(&mut bx, dst);
  82                 let src_val = self.codegen_operand(&mut bx, src);
  83                 let count = self.codegen_operand(&mut bx, count).immediate();
  84                 let pointee_layout = dst_val
  85                     .layout
  86                     .pointee_info_at(&bx, rustc_target::abi::Size::ZERO)
  87                     .expect("Expected pointer");
  88                 let bytes = bx.mul(count, bx.const_usize(pointee_layout.size.bytes()));
  89
  90                 let align = pointee_layout.align;
  91                 let dst = dst_val.immediate();
  92                 let src = src_val.immediate();
  93                 bx.memcpy(dst, align, src, align, bytes, crate::MemFlags::empty());
  94                 bx
  95             }
  96             mir::StatementKind::FakeRead(..)
  97             | mir::StatementKind::Retag { .. }
  98             | mir::StatementKind::AscribeUserType(..)
  99             | mir::StatementKind::Nop => bx,
 100         }
 101     }
 102 }