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trans: noop drops don't need their lvalue in an alloca.

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This commit is contained in:
Eduard Burtescu 2016-06-09 18:15:15 +03:00
parent eb9cb4dbca
commit bec32eb4ff
2 changed files with 15 additions and 3 deletions
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11
src/librustc_trans/mir/analyze.rs
View file

@ -18,6 +18,7 @@ use rustc::mir::repr::TerminatorKind;
use rustc::mir::visit::{Visitor, LvalueContext};
use rustc::mir::traversal;
use common::{self, Block, BlockAndBuilder};
use glue;
use super::rvalue;
pub fn lvalue_temps<'bcx,'tcx>(bcx: Block<'bcx,'tcx>,
@ -138,13 +139,21 @@ impl<'mir, 'bcx, 'tcx> Visitor<'tcx> for TempAnalyzer<'mir, 'bcx, 'tcx> {
LvalueContext::Consume => {
}
LvalueContext::Store |
LvalueContext::Drop |
LvalueContext::Inspect |
LvalueContext::Borrow { .. } |
LvalueContext::Slice { .. } |
LvalueContext::Projection => {
self.mark_as_lvalue(temp.index());
}
LvalueContext::Drop => {
let ty = self.mir.temp_decls[index as usize].ty;
let ty = self.bcx.monomorphize(&ty);
// Only need the lvalue if we're actually dropping it.
if glue::type_needs_drop(self.bcx.tcx(), ty) {
self.mark_as_lvalue(index as usize);
}
}
}
}
_ => {

7
src/librustc_trans/mir/block.rs
View file

@ -196,13 +196,16 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
}
mir::TerminatorKind::Drop { ref location, target, unwind } => {
let lvalue = self.trans_lvalue(&bcx, location);
let ty = lvalue.ty.to_ty(bcx.tcx());
let ty = mir.lvalue_ty(bcx.tcx(), location).to_ty(bcx.tcx());
let ty = bcx.monomorphize(&ty);
// Double check for necessity to drop
if !glue::type_needs_drop(bcx.tcx(), ty) {
funclet_br(self, bcx, target);
return;
}
let lvalue = self.trans_lvalue(&bcx, location);
let drop_fn = glue::get_drop_glue(bcx.ccx(), ty);
let drop_ty = glue::get_drop_glue_type(bcx.tcx(), ty);
let llvalue = if drop_ty != ty {