Auto merge of #122975 - DianQK:simplify_ub_check, r= · rust-lang/rust@98cd703 (original) (raw)
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`//! Performs various peephole optimizations.
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`use crate::simplify::simplify_duplicate_switch_targets;
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use rustc_ast::attr;
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`use rustc_middle::mir::*;
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`use rustc_middle::ty::layout;
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`use rustc_middle::ty::layout::ValidityRequirement;
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`use rustc_middle::ty::{self, GenericArgsRef, ParamEnv, Ty, TyCtxt};
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use rustc_span::sym;
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`use rustc_span::symbol::Symbol;
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`use rustc_target::abi::FieldIdx;
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`use rustc_target::spec::abi::Abi;
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`@@ -22,10 +24,17 @@ impl<'tcx> MirPass<'tcx> for InstSimplify {
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`local_decls: &body.local_decls,
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`param_env: tcx.param_env_reveal_all_normalized(body.source.def_id()),
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`};
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// FIXME(#116171) Coverage related, also see unreachable_prop.rs.
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let preserve_ub_checks =
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attr::contains_name(tcx.hir().krate_attrs(), sym::rustc_preserve_ub_checks)
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|| tcx.sess.instrument_coverage();
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`for block in body.basic_blocks.as_mut() {
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`for statement in block.statements.iter_mut() {
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`match statement.kind {
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`StatementKind::Assign(box (_place, ref mut rvalue)) => {
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if !preserve_ub_checks {
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ctx.simplify_ub_check(&statement.source_info, rvalue);
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}
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` ctx.simplify_bool_cmp(&statement.source_info, rvalue);
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` ctx.simplify_ref_deref(&statement.source_info, rvalue);
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` ctx.simplify_len(&statement.source_info, rvalue);
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`@@ -140,6 +149,14 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> {
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`}
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`}
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fn simplify_ub_check(&self, source_info: &SourceInfo, rvalue: &mut Rvalue<'tcx>) {
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if let Rvalue::NullaryOp(NullOp::UbChecks, _) = *rvalue {
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let const_ = Const::from_bool(self.tcx, self.tcx.sess.opts.debug_assertions);
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let constant = ConstOperand { span: source_info.span, const_, user_ty: None };
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*rvalue = Rvalue::Use(Operand::Constant(Box::new(constant)));
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}
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}
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`fn simplify_cast(&self, rvalue: &mut Rvalue<'tcx>) {
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`if let Rvalue::Cast(kind, operand, cast_ty) = rvalue {
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`let operand_ty = operand.ty(self.local_decls, self.tcx);
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