01aec8d185
Prior to this commit, debuginfo was always generated by mapping a name to a Place. This has the side-effect that `SimplifyLocals` cannot remove locals that are only used for debuginfo because their other uses have been const-propagated. To allow these locals to be removed, we now allow debuginfo to point to a constant value. The `ConstProp` pass detects when debuginfo points to a local with a known constant value and replaces it with the value. This allows the later `SimplifyLocals` pass to remove the local.
91 lines
3.4 KiB
Rust
91 lines
3.4 KiB
Rust
use crate::mir::operand::OperandRef;
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use crate::traits::*;
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use rustc_middle::mir;
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use rustc_middle::mir::interpret::{ConstValue, ErrorHandled};
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use rustc_middle::ty::layout::HasTyCtxt;
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use rustc_middle::ty::{self, Ty};
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use rustc_span::source_map::Span;
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use rustc_target::abi::Abi;
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use super::FunctionCx;
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impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
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pub fn eval_mir_constant_to_operand(
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&self,
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bx: &mut Bx,
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constant: &mir::Constant<'tcx>,
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) -> Result<OperandRef<'tcx, Bx::Value>, ErrorHandled> {
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let val = self.eval_mir_constant(constant)?;
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let ty = self.monomorphize(constant.literal.ty);
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Ok(OperandRef::from_const(bx, val, ty))
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}
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pub fn eval_mir_constant(
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&self,
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constant: &mir::Constant<'tcx>,
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) -> Result<ConstValue<'tcx>, ErrorHandled> {
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match self.monomorphize(constant.literal).val {
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ty::ConstKind::Unevaluated(def, substs, promoted) => self
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.cx
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.tcx()
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.const_eval_resolve(ty::ParamEnv::reveal_all(), def, substs, promoted, None)
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.map_err(|err| {
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if promoted.is_none() {
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self.cx
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.tcx()
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.sess
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.span_err(constant.span, "erroneous constant encountered");
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}
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err
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}),
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ty::ConstKind::Value(value) => Ok(value),
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err => span_bug!(
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constant.span,
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"encountered bad ConstKind after monomorphizing: {:?}",
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err
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),
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}
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}
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/// process constant containing SIMD shuffle indices
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pub fn simd_shuffle_indices(
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&mut self,
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bx: &Bx,
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span: Span,
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ty: Ty<'tcx>,
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constant: Result<ConstValue<'tcx>, ErrorHandled>,
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) -> (Bx::Value, Ty<'tcx>) {
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constant
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.map(|val| {
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let field_ty = ty.builtin_index().unwrap();
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let c = ty::Const::from_value(bx.tcx(), val, ty);
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let values: Vec<_> = bx
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.tcx()
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.destructure_const(ty::ParamEnv::reveal_all().and(&c))
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.fields
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.iter()
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.map(|field| {
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if let Some(prim) = field.val.try_to_scalar() {
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let layout = bx.layout_of(field_ty);
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let scalar = match layout.abi {
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Abi::Scalar(ref x) => x,
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_ => bug!("from_const: invalid ByVal layout: {:#?}", layout),
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};
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bx.scalar_to_backend(prim, scalar, bx.immediate_backend_type(layout))
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} else {
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bug!("simd shuffle field {:?}", field)
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}
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})
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.collect();
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let llval = bx.const_struct(&values, false);
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(llval, c.ty)
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})
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.unwrap_or_else(|_| {
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bx.tcx().sess.span_err(span, "could not evaluate shuffle_indices at compile time");
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// We've errored, so we don't have to produce working code.
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let ty = self.monomorphize(ty);
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let llty = bx.backend_type(bx.layout_of(ty));
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(bx.const_undef(llty), ty)
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})
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}
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}
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