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Make permit_uninit/zero_init fallible

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This commit is contained in:
Michael Goulet 2023-02-14 00:59:40 +00:00
parent 087a0136d0
commit b096f0e0f0
9 changed files with 79 additions and 67 deletions
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44
compiler/rustc_mir_transform/src/instcombine.rs
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@ -6,7 +6,8 @@ use rustc_middle::mir::{
BinOp, Body, Constant, ConstantKind, LocalDecls, Operand, Place, ProjectionElem, Rvalue,
SourceInfo, Statement, StatementKind, Terminator, TerminatorKind, UnOp,
};
use rustc_middle::ty::{self, layout::TyAndLayout, ParamEnv, ParamEnvAnd, SubstsRef, Ty, TyCtxt};
use rustc_middle::ty::layout::LayoutError;
use rustc_middle::ty::{self, ParamEnv, ParamEnvAnd, SubstsRef, Ty, TyCtxt};
use rustc_span::symbol::{sym, Symbol};
pub struct InstCombine;
@ -230,38 +231,41 @@ impl<'tcx> InstCombineContext<'tcx, '_> {
// Check this is a foldable intrinsic before we query the layout of our generic parameter
let Some(assert_panics) = intrinsic_assert_panics(intrinsic_name) else { return; };
let Ok(layout) = self.tcx.layout_of(self.param_env.and(ty)) else { return; };
if assert_panics(self.tcx, self.param_env.and(layout)) {
// If we know the assert panics, indicate to later opts that the call diverges
*target = None;
} else {
// If we know the assert does not panic, turn the call into a Goto
terminator.kind = TerminatorKind::Goto { target: *target_block };
match assert_panics(self.tcx, self.param_env.and(ty)) {
// We don't know the layout, don't touch the assertion
Err(_) => {}
Ok(true) => {
// If we know the assert panics, indicate to later opts that the call diverges
*target = None;
}
Ok(false) => {
// If we know the assert does not panic, turn the call into a Goto
terminator.kind = TerminatorKind::Goto { target: *target_block };
}
}
}
}
fn intrinsic_assert_panics<'tcx>(
intrinsic_name: Symbol,
) -> Option<fn(TyCtxt<'tcx>, ParamEnvAnd<'tcx, TyAndLayout<'tcx>>) -> bool> {
) -> Option<fn(TyCtxt<'tcx>, ParamEnvAnd<'tcx, Ty<'tcx>>) -> Result<bool, LayoutError<'tcx>>> {
fn inhabited_predicate<'tcx>(
_tcx: TyCtxt<'tcx>,
param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
) -> bool {
let (_param_env, layout) = param_env_and_layout.into_parts();
layout.abi.is_uninhabited()
tcx: TyCtxt<'tcx>,
param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Result<bool, LayoutError<'tcx>> {
Ok(tcx.layout_of(param_env_and_ty)?.abi.is_uninhabited())
}
fn zero_valid_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
) -> bool {
!tcx.permits_zero_init(param_env_and_layout)
param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Result<bool, LayoutError<'tcx>> {
Ok(!tcx.permits_zero_init(param_env_and_ty)?)
}
fn mem_uninitialized_valid_predicate<'tcx>(
tcx: TyCtxt<'tcx>,
param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
) -> bool {
!tcx.permits_uninit_init(param_env_and_layout)
param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
) -> Result<bool, LayoutError<'tcx>> {
Ok(!tcx.permits_uninit_init(param_env_and_ty)?)
}
match intrinsic_name {