From 5804c3b2f83c53ea6fc1a95852e20f627128faf6 Mon Sep 17 00:00:00 2001 From: Wesley Wiser Date: Sun, 15 Sep 2019 12:08:09 -0400 Subject: [PATCH] Cleanup const_prop() some --- src/librustc_mir/transform/const_prop.rs | 147 ++++++++++++----------- 1 file changed, 75 insertions(+), 72 deletions(-) diff --git a/src/librustc_mir/transform/const_prop.rs b/src/librustc_mir/transform/const_prop.rs index c586e36412a4f..e9ede29bc486c 100644 --- a/src/librustc_mir/transform/const_prop.rs +++ b/src/librustc_mir/transform/const_prop.rs @@ -118,7 +118,7 @@ impl<'tcx> MirPass<'tcx> for ConstProp { struct ConstPropMachine; impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine { - type MemoryKinds= !; + type MemoryKinds = !; type PointerTag = (); type ExtraFnVal = !; @@ -460,79 +460,80 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { let span = source_info.span; // perform any special checking for specific Rvalue types - if let Rvalue::UnaryOp(op, arg) = rvalue { - trace!("checking UnaryOp(op = {:?}, arg = {:?})", op, arg); - let overflow_check = self.tcx.sess.overflow_checks(); - - self.use_ecx(source_info, |this| { - // We check overflow in debug mode already - // so should only check in release mode. - if *op == UnOp::Neg && !overflow_check { - let ty = arg.ty(&this.local_decls, this.tcx); - - if ty.is_integral() { - let arg = this.ecx.eval_operand(arg, None)?; - let prim = this.ecx.read_immediate(arg)?; - // Need to do overflow check here: For actual CTFE, MIR - // generation emits code that does this before calling the op. - if prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) { - throw_panic!(OverflowNeg) + match rvalue { + Rvalue::UnaryOp(UnOp::Neg, arg) => { + trace!("checking UnaryOp(op = Neg, arg = {:?})", arg); + let overflow_check = self.tcx.sess.overflow_checks(); + + self.use_ecx(source_info, |this| { + // We check overflow in debug mode already + // so should only check in release mode. + if !overflow_check { + let ty = arg.ty(&this.local_decls, this.tcx); + + if ty.is_integral() { + let arg = this.ecx.eval_operand(arg, None)?; + let prim = this.ecx.read_immediate(arg)?; + // Need to do overflow check here: For actual CTFE, MIR + // generation emits code that does this before calling the op. + if prim.to_bits()? == (1 << (prim.layout.size.bits() - 1)) { + throw_panic!(OverflowNeg) + } } } - } - Ok(()) - })?; - } else if let Rvalue::BinaryOp(op, left, right) = rvalue { - trace!("checking BinaryOp(op = {:?}, left = {:?}, right = {:?})", op, left, right); - - let r = self.use_ecx(source_info, |this| { - this.ecx.read_immediate(this.ecx.eval_operand(right, None)?) - })?; - if *op == BinOp::Shr || *op == BinOp::Shl { - let left_bits = place_layout.size.bits(); - let right_size = r.layout.size; - let r_bits = r.to_scalar().and_then(|r| r.to_bits(right_size)); - if r_bits.ok().map_or(false, |b| b >= left_bits as u128) { - let source_scope_local_data = match self.source_scope_local_data { - ClearCrossCrate::Set(ref data) => data, - ClearCrossCrate::Clear => return None, - }; - let dir = if *op == BinOp::Shr { - "right" - } else { - "left" - }; - let hir_id = source_scope_local_data[source_info.scope].lint_root; - self.tcx.lint_hir( - ::rustc::lint::builtin::EXCEEDING_BITSHIFTS, - hir_id, - span, - &format!("attempt to shift {} with overflow", dir)); - return None; - } + Ok(()) + })?; } - self.use_ecx(source_info, |this| { - let l = this.ecx.read_immediate(this.ecx.eval_operand(left, None)?)?; - let (_, overflow, _ty) = this.ecx.overflowing_binary_op(*op, l, r)?; - - // We check overflow in debug mode already - // so should only check in release mode. - if !this.tcx.sess.overflow_checks() && overflow { - let err = err_panic!(Overflow(*op)).into(); - return Err(err); + + Rvalue::BinaryOp(op, left, right) => { + trace!("checking BinaryOp(op = {:?}, left = {:?}, right = {:?})", op, left, right); + + let r = self.use_ecx(source_info, |this| { + this.ecx.read_immediate(this.ecx.eval_operand(right, None)?) + })?; + if *op == BinOp::Shr || *op == BinOp::Shl { + let left_bits = place_layout.size.bits(); + let right_size = r.layout.size; + let r_bits = r.to_scalar().and_then(|r| r.to_bits(right_size)); + if r_bits.ok().map_or(false, |b| b >= left_bits as u128) { + let source_scope_local_data = match self.source_scope_local_data { + ClearCrossCrate::Set(ref data) => data, + ClearCrossCrate::Clear => return None, + }; + let dir = if *op == BinOp::Shr { + "right" + } else { + "left" + }; + let hir_id = source_scope_local_data[source_info.scope].lint_root; + self.tcx.lint_hir( + ::rustc::lint::builtin::EXCEEDING_BITSHIFTS, + hir_id, + span, + &format!("attempt to shift {} with overflow", dir)); + return None; + } } + self.use_ecx(source_info, |this| { + let l = this.ecx.read_immediate(this.ecx.eval_operand(left, None)?)?; + let (_, overflow, _ty) = this.ecx.overflowing_binary_op(*op, l, r)?; + + // We check overflow in debug mode already + // so should only check in release mode. + if !this.tcx.sess.overflow_checks() && overflow { + let err = err_panic!(Overflow(*op)).into(); + return Err(err); + } - Ok(()) - })?; - } else if let Rvalue::Ref(_, _, place) = rvalue { - trace!("checking Ref({:?})", place); - // FIXME(wesleywiser) we don't currently handle the case where we try to make a ref - // from a function argument that hasn't been assigned to in this function. - if let Place { - base: PlaceBase::Local(local), - projection: box [] - } = place { + Ok(()) + })?; + } + + Rvalue::Ref(_, _, Place { base: PlaceBase::Local(local), projection: box [] }) => { + trace!("checking Ref({:?})", place); + // FIXME(wesleywiser) we don't currently handle the case where we try to make a ref + // from a function argument that hasn't been assigned to in this function. let alive = if let LocalValue::Live(_) = self.ecx.frame().locals[*local].value { true @@ -543,12 +544,14 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> { return None; } } - } else if let Rvalue::Aggregate(_, operands) = rvalue { - // FIXME(wesleywiser): const eval will turn this into a `const Scalar()` that - // `SimplifyLocals` doesn't know it can remove. - if operands.len() == 0 { + + Rvalue::Aggregate(_, operands) if operands.len() == 0 => { + // FIXME(wesleywiser): const eval will turn this into a `const Scalar()` that + // `SimplifyLocals` doesn't know it can remove. return None; } + + _ => { } } self.use_ecx(source_info, |this| {