diff options
| -rw-r--r-- | src/librustc_mir/build/block.rs | 28 | ||||
| -rw-r--r-- | src/librustc_mir/build/cfg.rs | 7 | ||||
| -rw-r--r-- | src/librustc_mir/build/expr/as_rvalue.rs | 65 |
3 files changed, 54 insertions, 46 deletions
diff --git a/src/librustc_mir/build/block.rs b/src/librustc_mir/build/block.rs index c1626b93f0c..01930d0ddc0 100644 --- a/src/librustc_mir/build/block.rs +++ b/src/librustc_mir/build/block.rs @@ -12,6 +12,7 @@ use build::{BlockAnd, BlockAndExtension, Builder}; use hair::*; use rustc::mir::repr::*; use rustc::hir; +use syntax::codemap::Span; impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { pub fn ast_block(&mut self, @@ -81,4 +82,31 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { block.unit() }) } + + // Helper method for generating MIR inside a conditional block. + pub fn with_cond<F>(&mut self, block: BasicBlock, span: Span, + cond: Operand<'tcx>, f: F) -> BasicBlock + where F: FnOnce(&mut Builder<'a, 'gcx, 'tcx>, BasicBlock) -> BasicBlock { + let scope_id = self.innermost_scope_id(); + + let then_block = self.cfg.start_new_block(); + let else_block = self.cfg.start_new_block(); + + self.cfg.terminate(block, scope_id, span, + TerminatorKind::If { + cond: cond, + targets: (then_block, else_block) + }); + + let after = f(self, then_block); + + // If the returned block isn't terminated, add a branch to the "else" + // block + if !self.cfg.terminated(after) { + self.cfg.terminate(after, scope_id, span, + TerminatorKind::Goto { target: else_block }); + } + + else_block + } } diff --git a/src/librustc_mir/build/cfg.rs b/src/librustc_mir/build/cfg.rs index 4859257f291..7ffef989e2f 100644 --- a/src/librustc_mir/build/cfg.rs +++ b/src/librustc_mir/build/cfg.rs @@ -86,7 +86,7 @@ impl<'tcx> CFG<'tcx> { scope: ScopeId, span: Span, kind: TerminatorKind<'tcx>) { - debug_assert!(self.block_data(block).terminator.is_none(), + debug_assert!(!self.terminated(block), "terminate: block {:?} already has a terminator set", block); self.block_data_mut(block).terminator = Some(Terminator { span: span, @@ -94,4 +94,9 @@ impl<'tcx> CFG<'tcx> { kind: kind, }); } + + /// Returns whether or not the given block has been terminated or not + pub fn terminated(&self, block: BasicBlock) -> bool { + self.block_data(block).terminator.is_some() + } } diff --git a/src/librustc_mir/build/expr/as_rvalue.rs b/src/librustc_mir/build/expr/as_rvalue.rs index b5b4a01dcc6..04609e7f8dd 100644 --- a/src/librustc_mir/build/expr/as_rvalue.rs +++ b/src/librustc_mir/build/expr/as_rvalue.rs @@ -88,18 +88,11 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { this.cfg.push_assign(block, scope_id, expr_span, &is_min, Rvalue::BinaryOp(BinOp::Eq, arg.clone(), minval)); - let of_block = this.cfg.start_new_block(); - let ok_block = this.cfg.start_new_block(); - - this.cfg.terminate(block, scope_id, expr_span, - TerminatorKind::If { - cond: Operand::Consume(is_min), - targets: (of_block, ok_block) - }); - - this.panic(of_block, "attempted to negate with overflow", expr_span); - - block = ok_block; + block = this.with_cond( + block, expr_span, Operand::Consume(is_min), |this, block| { + this.panic(block, "attempted to negate with overflow", expr_span); + block + }); } block.and(Rvalue::UnaryOp(op, arg)) } @@ -268,21 +261,18 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { let val = result_value.clone().field(val_fld, ty); let of = result_value.field(of_fld, bool_ty); - let success = self.cfg.start_new_block(); - let failure = self.cfg.start_new_block(); - - self.cfg.terminate(block, scope_id, span, - TerminatorKind::If { - cond: Operand::Consume(of), - targets: (failure, success) - }); let msg = if op == BinOp::Shl || op == BinOp::Shr { "shift operation overflowed" } else { "arithmetic operation overflowed" }; - self.panic(failure, msg, span); - success.and(Rvalue::Use(Operand::Consume(val))) + + block = self.with_cond(block, span, Operand::Consume(of), |this, block| { + this.panic(block, msg, span); + block + }); + + block.and(Rvalue::Use(Operand::Consume(val))) } else { if ty.is_integral() && (op == BinOp::Div || op == BinOp::Rem) { // Checking division and remainder is more complex, since we 1. always check @@ -302,17 +292,10 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { self.cfg.push_assign(block, scope_id, span, &is_zero, Rvalue::BinaryOp(BinOp::Eq, rhs.clone(), zero)); - let zero_block = self.cfg.start_new_block(); - let ok_block = self.cfg.start_new_block(); - - self.cfg.terminate(block, scope_id, span, - TerminatorKind::If { - cond: Operand::Consume(is_zero), - targets: (zero_block, ok_block) - }); - - self.panic(zero_block, zero_msg, span); - block = ok_block; + block = self.with_cond(block, span, Operand::Consume(is_zero), |this, block| { + this.panic(block, zero_msg, span); + block + }); // We only need to check for the overflow in one case: // MIN / -1, and only for signed values. @@ -336,18 +319,10 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> { self.cfg.push_assign(block, scope_id, span, &of, Rvalue::BinaryOp(BinOp::BitAnd, is_neg_1, is_min)); - let of_block = self.cfg.start_new_block(); - let ok_block = self.cfg.start_new_block(); - - self.cfg.terminate(block, scope_id, span, - TerminatorKind::If { - cond: Operand::Consume(of), - targets: (of_block, ok_block) - }); - - self.panic(of_block, overflow_msg, span); - - block = ok_block; + block = self.with_cond(block, span, Operand::Consume(of), |this, block| { + this.panic(block, overflow_msg, span); + block + }); } } |