directly push stackframes for constants when they are encountered
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6b939bbd79
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@ -14,7 +14,7 @@
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use std::{iter, mem};
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use syntax::ast;
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use syntax::attr;
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use syntax::codemap::{self, DUMMY_SP, Span};
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use syntax::codemap::{self, DUMMY_SP};
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use error::{EvalError, EvalResult};
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use memory::{Memory, Pointer};
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@ -94,9 +94,6 @@ struct Frame<'a, 'tcx: 'a> {
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/// The index of the currently evaluated statment
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stmt: usize,
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// Constants that need to be evaluated before the next statement can be evaluated
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constants: Vec<(ConstantId<'tcx>, Span, Pointer, CachedMir<'a, 'tcx>)>,
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}
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#[derive(Copy, Clone, Debug, Eq, PartialEq)]
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@ -409,7 +406,7 @@ fn run(&mut self) -> EvalResult<()> {
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loop {
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match stepper.step()? {
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Constant => trace!("next statement requires the computation of a constant"),
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Constant => trace!("computing a constant"),
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Assignment => trace!("{:?}", stepper.stmt()),
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Terminator => {
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trace!("{:?}", stepper.term().kind);
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@ -444,7 +441,6 @@ fn push_stack_frame(&mut self, def_id: DefId, span: codemap::Span, mir: CachedMi
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def_id: def_id,
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substs: substs,
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stmt: 0,
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constants: Vec::new(),
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});
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let locals: Vec<Pointer> = arg_tys.chain(var_tys).chain(temp_tys).map(|ty| {
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@ -4,7 +4,6 @@
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TerminatorTarget,
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ConstantId,
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GlobalEvalContext,
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Frame,
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};
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use error::EvalResult;
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use rustc::mir::repr as mir;
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@ -13,6 +12,7 @@
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use rustc::mir::visit::{Visitor, LvalueContext};
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use syntax::codemap::Span;
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use std::rc::Rc;
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use memory::Pointer;
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pub enum Event {
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Constant,
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@ -24,6 +24,10 @@ pub enum Event {
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pub struct Stepper<'fncx, 'a: 'fncx, 'b: 'a + 'mir, 'mir: 'fncx, 'tcx: 'b>{
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fncx: &'fncx mut FnEvalContext<'a, 'b, 'mir, 'tcx>,
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process: fn (&mut Stepper<'fncx, 'a, 'b, 'mir, 'tcx>) -> EvalResult<()>,
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// a cache of the constants to be computed before the next statement/terminator
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// this is an optimization, so we don't have to allocate a new vector for every statement
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constants: Vec<(ConstantId<'tcx>, Span, Pointer, CachedMir<'mir, 'tcx>)>,
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}
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impl<'fncx, 'a, 'b: 'a + 'mir, 'mir, 'tcx: 'b> Stepper<'fncx, 'a, 'b, 'mir, 'tcx> {
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@ -31,6 +35,7 @@ pub(super) fn new(fncx: &'fncx mut FnEvalContext<'a, 'b, 'mir, 'tcx>) -> Self {
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Stepper {
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fncx: fncx,
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process: Self::dummy,
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constants: Vec::new(),
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}
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}
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@ -60,7 +65,6 @@ fn terminator(&mut self) -> EvalResult<()> {
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match term {
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TerminatorTarget::Block => {},
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TerminatorTarget::Return => {
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assert!(self.fncx.frame().constants.is_empty());
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self.fncx.pop_stack_frame();
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},
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TerminatorTarget::Call => {},
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@ -68,14 +72,6 @@ fn terminator(&mut self) -> EvalResult<()> {
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Ok(())
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}
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fn constant(&mut self) -> EvalResult<()> {
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let (cid, span, return_ptr, mir) = self.fncx.frame_mut().constants.pop().expect("state machine broken");
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let def_id = cid.def_id();
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let substs = cid.substs();
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self.fncx.push_stack_frame(def_id, span, mir, substs, Some(return_ptr));
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Ok(())
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}
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pub fn step(&mut self) -> EvalResult<Event> {
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(self.process)(self)?;
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@ -85,48 +81,60 @@ pub fn step(&mut self) -> EvalResult<Event> {
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return Ok(Event::Done);
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}
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if !self.fncx.frame().constants.is_empty() {
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self.process = Self::constant;
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return Ok(Event::Constant);
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}
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let block = self.fncx.frame().next_block;
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let stmt = self.fncx.frame().stmt;
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let mir = self.fncx.mir();
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let basic_block = mir.basic_block_data(block);
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if let Some(ref stmt) = basic_block.statements.get(stmt) {
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assert!(self.fncx.frame().constants.is_empty());
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assert!(self.constants.is_empty());
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ConstantExtractor {
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span: stmt.span,
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substs: self.fncx.substs(),
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def_id: self.fncx.frame().def_id,
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gecx: self.fncx.gecx,
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frame: self.fncx.stack.last_mut().expect("stack empty"),
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constants: &mut self.constants,
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mir: &mir,
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}.visit_statement(block, stmt);
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if self.fncx.frame().constants.is_empty() {
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if self.constants.is_empty() {
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self.process = Self::statement;
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return Ok(Event::Assignment);
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} else {
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self.process = Self::constant;
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self.process = Self::statement;
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self.extract_constants();
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return Ok(Event::Constant);
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}
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}
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let terminator = basic_block.terminator();
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assert!(self.fncx.frame().constants.is_empty());
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assert!(self.constants.is_empty());
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ConstantExtractor {
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span: terminator.span,
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substs: self.fncx.substs(),
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def_id: self.fncx.frame().def_id,
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gecx: self.fncx.gecx,
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frame: self.fncx.stack.last_mut().expect("stack empty"),
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constants: &mut self.constants,
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mir: &mir,
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}.visit_terminator(block, terminator);
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if self.fncx.frame().constants.is_empty() {
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if self.constants.is_empty() {
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self.process = Self::terminator;
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Ok(Event::Terminator)
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} else {
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self.process = Self::constant;
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self.process = Self::statement;
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self.extract_constants();
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Ok(Event::Constant)
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}
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}
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fn extract_constants(&mut self) {
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assert!(!self.constants.is_empty());
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for (cid, span, return_ptr, mir) in self.constants.drain(..) {
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let def_id = cid.def_id();
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let substs = cid.substs();
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self.fncx.push_stack_frame(def_id, span, mir, substs, Some(return_ptr));
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}
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}
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/// returns the statement that will be processed next
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pub fn stmt(&self) -> &mir::Statement {
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&self.fncx.basic_block().statements[self.fncx.frame().stmt]
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@ -144,8 +152,11 @@ pub fn block(&self) -> mir::BasicBlock {
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struct ConstantExtractor<'a, 'b: 'mir, 'mir: 'a, 'tcx: 'b> {
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span: Span,
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frame: &'a mut Frame<'mir, 'tcx>,
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constants: &'a mut Vec<(ConstantId<'tcx>, Span, Pointer, CachedMir<'mir, 'tcx>)>,
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gecx: &'a mut GlobalEvalContext<'b, 'tcx>,
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mir: &'a mir::Mir<'tcx>,
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def_id: DefId,
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substs: &'tcx subst::Substs<'tcx>,
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}
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impl<'a, 'b, 'mir, 'tcx> ConstantExtractor<'a, 'b, 'mir, 'tcx> {
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@ -160,7 +171,7 @@ fn static_item(&mut self, def_id: DefId, substs: &'tcx subst::Substs<'tcx>, span
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let mir = self.gecx.load_mir(def_id);
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let ptr = self.gecx.alloc_ret_ptr(mir.return_ty, substs).expect("there's no such thing as an unreachable static");
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self.gecx.statics.insert(cid.clone(), ptr);
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self.frame.constants.push((cid, span, ptr, mir));
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self.constants.push((cid, span, ptr, mir));
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}
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}
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@ -180,19 +191,19 @@ fn visit_constant(&mut self, constant: &mir::Constant<'tcx>) {
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},
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mir::Literal::Promoted { index } => {
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let cid = ConstantId::Promoted {
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def_id: self.frame.def_id,
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substs: self.frame.substs,
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def_id: self.def_id,
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substs: self.substs,
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index: index,
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};
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if self.gecx.statics.contains_key(&cid) {
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return;
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}
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let mir = self.frame.mir.promoted[index].clone();
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let mir = self.mir.promoted[index].clone();
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let return_ty = mir.return_ty;
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let return_ptr = self.gecx.alloc_ret_ptr(return_ty, cid.substs()).expect("there's no such thing as an unreachable static");
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let mir = CachedMir::Owned(Rc::new(mir));
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self.gecx.statics.insert(cid.clone(), return_ptr);
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self.frame.constants.push((cid, constant.span, return_ptr, mir));
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self.constants.push((cid, constant.span, return_ptr, mir));
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}
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}
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}
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