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     pub fn codegen_statement(&mut self, mut bx: Bx, statement: &mir::Statement<'tcx>) -> Bx {
  10         debug!("codegen_statement(statement={:?})", statement);
  11
  12         self.set_debug_loc(&mut bx, statement.source_info);
  13         match statement.kind {
  14             mir::StatementKind::Assign(box (ref place, ref rvalue)) => {
  15                 if let Some(index) = place.as_local() {
  16                     match self.locals[index] {
  17                         LocalRef::Place(cg_dest) => self.codegen_rvalue(bx, cg_dest, rvalue),
  18                         LocalRef::UnsizedPlace(cg_indirect_dest) => {
  19                             self.codegen_rvalue_unsized(bx, cg_indirect_dest, rvalue)
  20                         }
  21                         LocalRef::Operand(None) => {
  22                             let (mut bx, operand) = self.codegen_rvalue_operand(bx, rvalue);
  23                             self.locals[index] = LocalRef::Operand(Some(operand));
  24                             self.debug_introduce_local(&mut bx, index);
  25                             bx
  26                         }
  27                         LocalRef::Operand(Some(op)) => {
  28                             if !op.layout.is_zst() {
  29                                 span_bug!(
  30                                     statement.source_info.span,
  31                                     "operand {:?} already assigned",
  32                                     rvalue
  33                                 );
  34                             }
  35
  36                             // If the type is zero-sized, it's already been set here,
  37                             // but we still need to make sure we codegen the operand
  38                             self.codegen_rvalue_operand(bx, rvalue).0
  39                         }
  40                     }
  41                 } else {
  42                     let cg_dest = self.codegen_place(&mut bx, place.as_ref());
  43                     self.codegen_rvalue(bx, cg_dest, rvalue)
  44                 }
  45             }
  46             mir::StatementKind::SetDiscriminant { box ref place, variant_index } => {
  47                 self.codegen_place(&mut bx, place.as_ref())
  48                     .codegen_set_discr(&mut bx, variant_index);
  49                 bx
  50             }
  51             mir::StatementKind::StorageLive(local) => {
  52                 if let LocalRef::Place(cg_place) = self.locals[local] {
  53                     cg_place.storage_live(&mut bx);
  54                 } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
  55                     cg_indirect_place.storage_live(&mut bx);
  56                 }
  57                 bx
  58             }
  59             mir::StatementKind::StorageDead(local) => {
  60                 if let LocalRef::Place(cg_place) = self.locals[local] {
  61                     cg_place.storage_dead(&mut bx);
  62                 } else if let LocalRef::UnsizedPlace(cg_indirect_place) = self.locals[local] {
  63                     cg_indirect_place.storage_dead(&mut bx);
  64                 }
  65                 bx
  66             }
  67             mir::StatementKind::Coverage(box ref coverage) => {
  68                 self.codegen_coverage(&mut bx, coverage.clone(), statement.source_info.scope);
  69                 bx
  70             }
  71             mir::StatementKind::CopyNonOverlapping(box mir::CopyNonOverlapping {
  72                 ref src,
  73                 ref dst,
  74                 ref count,
  75             }) => {
  76                 let dst_val = self.codegen_operand(&mut bx, dst);
  77                 let src_val = self.codegen_operand(&mut bx, src);
  78                 let count = self.codegen_operand(&mut bx, count).immediate();
  79                 let pointee_layout = dst_val
  80                     .layout
  81                     .pointee_info_at(&bx, rustc_target::abi::Size::ZERO)
  82                     .expect("Expected pointer");
  83                 let bytes = bx.mul(count, bx.const_usize(pointee_layout.size.bytes()));
  84
  85                 let align = pointee_layout.align;
  86                 let dst = dst_val.immediate();
  87                 let src = src_val.immediate();
  88                 bx.memcpy(dst, align, src, align, bytes, crate::MemFlags::empty());
  89                 bx
  90             }
  91             mir::StatementKind::FakeRead(..)
  92             | mir::StatementKind::Retag { .. }
  93             | mir::StatementKind::AscribeUserType(..)
  94             | mir::StatementKind::Nop => bx,
  95         }
  96     }
  97 }