bjoernager/rust
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Fold consecutive PtrToPtr casts.

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This commit is contained in:
Camille GILLOT 2023-10-11 19:39:18 +00:00
parent f4cfd87202
commit 1f544ca0cc
13 changed files with 507 additions and 509 deletions
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56
compiler/rustc_mir_transform/src/gvn.rs
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@ -93,7 +93,6 @@ use rustc_index::IndexVec;
use rustc_middle::mir::interpret::GlobalAlloc;
use rustc_middle::mir::visit::*;
use rustc_middle::mir::*;
use rustc_middle::ty::adjustment::PointerCoercion;
use rustc_middle::ty::layout::LayoutOf;
use rustc_middle::ty::{self, Ty, TyCtxt, TypeAndMut};
use rustc_span::def_id::DefId;
@ -778,18 +777,8 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
// Operations.
Rvalue::Len(ref mut place) => return self.simplify_len(place, location),
Rvalue::Cast(kind, ref mut value, to) => {
let from = value.ty(self.local_decls, self.tcx);
let value = self.simplify_operand(value, location)?;
if let CastKind::PointerCoercion(
PointerCoercion::ReifyFnPointer | PointerCoercion::ClosureFnPointer(_),
) = kind
{
// Each reification of a generic fn may get a different pointer.
// Do not try to merge them.
return self.new_opaque();
}
Value::Cast { kind, value, from, to }
Rvalue::Cast(ref mut kind, ref mut value, to) => {
return self.simplify_cast(kind, value, to, location);
}
Rvalue::BinaryOp(op, box (ref mut lhs, ref mut rhs)) => {
let ty = lhs.ty(self.local_decls, self.tcx);
@ -1035,6 +1024,47 @@ impl<'body, 'tcx> VnState<'body, 'tcx> {
}
}
fn simplify_cast(
&mut self,
kind: &mut CastKind,
operand: &mut Operand<'tcx>,
to: Ty<'tcx>,
location: Location,
) -> Option<VnIndex> {
use rustc_middle::ty::adjustment::PointerCoercion::*;
use CastKind::*;
let mut from = operand.ty(self.local_decls, self.tcx);
let mut value = self.simplify_operand(operand, location)?;
if let CastKind::PointerCoercion(ReifyFnPointer | ClosureFnPointer(_)) = kind {
// Each reification of a generic fn may get a different pointer.
// Do not try to merge them.
return self.new_opaque();
}
if let PtrToPtr | PointerCoercion(MutToConstPointer) = kind
&& let Value::Cast { kind: inner_kind, value: inner_value, from: inner_from, to: _ } =
*self.get(value)
&& let PtrToPtr | PointerCoercion(MutToConstPointer) = inner_kind
{
from = inner_from;
value = inner_value;
*kind = PtrToPtr;
if inner_from == to {
return Some(inner_value);
}
if let Some(const_) = self.try_as_constant(value) {
*operand = Operand::Constant(Box::new(const_));
} else if let Some(local) = self.try_as_local(value, location) {
*operand = Operand::Copy(local.into());
self.reused_locals.insert(local);
}
}
Some(self.insert(Value::Cast { kind: *kind, value, from, to }))
}
fn simplify_len(&mut self, place: &mut Place<'tcx>, location: Location) -> Option<VnIndex> {
// Trivial case: we are fetching a statically known length.
let place_ty = place.ty(self.local_decls, self.tcx).ty;