From fbc3f11fc18a626ba9b9f6bc52de4fc5ef75154b Mon Sep 17 00:00:00 2001
From: Ulrik Sverdrup <bluss@users.noreply.github.com>
Date: Fri, 9 Dec 2016 16:28:54 +0100
Subject: [PATCH] mir: Reinstate while loop in deaggregator pass
A previous commit must have removed the `while let` loop here by
mistake; for each basic block, it should find and deaggregate multiple
statements in their index order, and the `curr` index tracks the
progress through the block.
This fixes both the case of deaggregating statements in separate
basic blocks (preserving `curr` could prevent that) as well
as multiple times in the same block (missing loop prevented that).
---
src/librustc_mir/transform/deaggregator.rs | 119 +++++++++---------
src/test/mir-opt/deaggregator_test_enum_2.rs | 57 +++++++++
.../mir-opt/deaggregator_test_multiple.rs | 48 +++++++
3 files changed, 164 insertions(+), 60 deletions(-)
create mode 100644 src/test/mir-opt/deaggregator_test_enum_2.rs
create mode 100644 src/test/mir-opt/deaggregator_test_multiple.rs
diff --git a/src/librustc_mir/transform/deaggregator.rs b/src/librustc_mir/transform/deaggregator.rs
index fcdeae6d6c0..e13c8e02137 100644
--- a/src/librustc_mir/transform/deaggregator.rs
+++ b/src/librustc_mir/transform/deaggregator.rs
@@ -36,71 +36,70 @@ impl<'tcx> MirPass<'tcx> for Deaggregator {
// In fact, we might not want to trigger in other cases.
// Ex: when we could use SROA. See issue #35259
- let mut curr: usize = 0;
for bb in mir.basic_blocks_mut() {
- let idx = match get_aggregate_statement_index(curr, &bb.statements) {
- Some(idx) => idx,
- None => continue,
- };
- // do the replacement
- debug!("removing statement {:?}", idx);
- let src_info = bb.statements[idx].source_info;
- let suffix_stmts = bb.statements.split_off(idx+1);
- let orig_stmt = bb.statements.pop().unwrap();
- let (lhs, rhs) = match orig_stmt.kind {
- StatementKind::Assign(ref lhs, ref rhs) => (lhs, rhs),
- _ => span_bug!(src_info.span, "expected assign, not {:?}", orig_stmt),
- };
- let (agg_kind, operands) = match rhs {
- &Rvalue::Aggregate(ref agg_kind, ref operands) => (agg_kind, operands),
- _ => span_bug!(src_info.span, "expected aggregate, not {:?}", rhs),
- };
- let (adt_def, variant, substs) = match agg_kind {
- &AggregateKind::Adt(adt_def, variant, substs, None) => (adt_def, variant, substs),
- _ => span_bug!(src_info.span, "expected struct, not {:?}", rhs),
- };
- let n = bb.statements.len();
- bb.statements.reserve(n + operands.len() + suffix_stmts.len());
- for (i, op) in operands.iter().enumerate() {
- let ref variant_def = adt_def.variants[variant];
- let ty = variant_def.fields[i].ty(tcx, substs);
- let rhs = Rvalue::Use(op.clone());
+ let mut curr: usize = 0;
+ while let Some(idx) = get_aggregate_statement_index(curr, &bb.statements) {
+ // do the replacement
+ debug!("removing statement {:?}", idx);
+ let src_info = bb.statements[idx].source_info;
+ let suffix_stmts = bb.statements.split_off(idx+1);
+ let orig_stmt = bb.statements.pop().unwrap();
+ let (lhs, rhs) = match orig_stmt.kind {
+ StatementKind::Assign(ref lhs, ref rhs) => (lhs, rhs),
+ _ => span_bug!(src_info.span, "expected assign, not {:?}", orig_stmt),
+ };
+ let (agg_kind, operands) = match rhs {
+ &Rvalue::Aggregate(ref agg_kind, ref operands) => (agg_kind, operands),
+ _ => span_bug!(src_info.span, "expected aggregate, not {:?}", rhs),
+ };
+ let (adt_def, variant, substs) = match agg_kind {
+ &AggregateKind::Adt(adt_def, variant, substs, None)
+ => (adt_def, variant, substs),
+ _ => span_bug!(src_info.span, "expected struct, not {:?}", rhs),
+ };
+ let n = bb.statements.len();
+ bb.statements.reserve(n + operands.len() + suffix_stmts.len());
+ for (i, op) in operands.iter().enumerate() {
+ let ref variant_def = adt_def.variants[variant];
+ let ty = variant_def.fields[i].ty(tcx, substs);
+ let rhs = Rvalue::Use(op.clone());
- let lhs_cast = if adt_def.variants.len() > 1 {
- Lvalue::Projection(Box::new(LvalueProjection {
- base: lhs.clone(),
- elem: ProjectionElem::Downcast(adt_def, variant),
- }))
- } else {
- lhs.clone()
+ let lhs_cast = if adt_def.variants.len() > 1 {
+ Lvalue::Projection(Box::new(LvalueProjection {
+ base: lhs.clone(),
+ elem: ProjectionElem::Downcast(adt_def, variant),
+ }))
+ } else {
+ lhs.clone()
+ };
+
+ let lhs_proj = Lvalue::Projection(Box::new(LvalueProjection {
+ base: lhs_cast,
+ elem: ProjectionElem::Field(Field::new(i), ty),
+ }));
+ let new_statement = Statement {
+ source_info: src_info,
+ kind: StatementKind::Assign(lhs_proj, rhs),
+ };
+ debug!("inserting: {:?} @ {:?}", new_statement, idx + i);
+ bb.statements.push(new_statement);
+ }
+
+ // if the aggregate was an enum, we need to set the discriminant
+ if adt_def.variants.len() > 1 {
+ let set_discriminant = Statement {
+ kind: StatementKind::SetDiscriminant {
+ lvalue: lhs.clone(),
+ variant_index: variant,
+ },
+ source_info: src_info,
+ };
+ bb.statements.push(set_discriminant);
};
- let lhs_proj = Lvalue::Projection(Box::new(LvalueProjection {
- base: lhs_cast,
- elem: ProjectionElem::Field(Field::new(i), ty),
- }));
- let new_statement = Statement {
- source_info: src_info,
- kind: StatementKind::Assign(lhs_proj, rhs),
- };
- debug!("inserting: {:?} @ {:?}", new_statement, idx + i);
- bb.statements.push(new_statement);
+ curr = bb.statements.len();
+ bb.statements.extend(suffix_stmts);
}
-
- // if the aggregate was an enum, we need to set the discriminant
- if adt_def.variants.len() > 1 {
- let set_discriminant = Statement {
- kind: StatementKind::SetDiscriminant {
- lvalue: lhs.clone(),
- variant_index: variant,
- },
- source_info: src_info,
- };
- bb.statements.push(set_discriminant);
- };
-
- curr = bb.statements.len();
- bb.statements.extend(suffix_stmts);
}
}
}
diff --git a/src/test/mir-opt/deaggregator_test_enum_2.rs b/src/test/mir-opt/deaggregator_test_enum_2.rs
new file mode 100644
index 00000000000..02d496b2901
--- /dev/null
+++ b/src/test/mir-opt/deaggregator_test_enum_2.rs
@@ -0,0 +1,57 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that deaggregate fires in more than one basic block
+
+enum Foo {
+ A(i32),
+ B(i32),
+}
+
+fn test1(x: bool, y: i32) -> Foo {
+ if x {
+ Foo::A(y)
+ } else {
+ Foo::B(y)
+ }
+}
+
+fn main() {}
+
+// END RUST SOURCE
+// START rustc.node12.Deaggregator.before.mir
+// bb1: {
+// _6 = _4;
+// _0 = Foo::A(_6,);
+// goto -> bb3;
+// }
+//
+// bb2: {
+// _7 = _4;
+// _0 = Foo::B(_7,);
+// goto -> bb3;
+// }
+// END rustc.node12.Deaggregator.before.mir
+// START rustc.node12.Deaggregator.after.mir
+// bb1: {
+// _6 = _4;
+// ((_0 as A).0: i32) = _6;
+// discriminant(_0) = 0;
+// goto -> bb3;
+// }
+//
+// bb2: {
+// _7 = _4;
+// ((_0 as B).0: i32) = _7;
+// discriminant(_0) = 1;
+// goto -> bb3;
+// }
+// END rustc.node12.Deaggregator.after.mir
+//
diff --git a/src/test/mir-opt/deaggregator_test_multiple.rs b/src/test/mir-opt/deaggregator_test_multiple.rs
new file mode 100644
index 00000000000..a180a69be55
--- /dev/null
+++ b/src/test/mir-opt/deaggregator_test_multiple.rs
@@ -0,0 +1,48 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Test that deaggregate fires more than once per block
+
+enum Foo {
+ A(i32),
+ B,
+}
+
+fn test(x: i32) -> [Foo; 2] {
+ [Foo::A(x), Foo::A(x)]
+}
+
+fn main() { }
+
+// END RUST SOURCE
+// START rustc.node10.Deaggregator.before.mir
+// bb0: {
+// _2 = _1;
+// _4 = _2;
+// _3 = Foo::A(_4,);
+// _6 = _2;
+// _5 = Foo::A(_6,);
+// _0 = [_3, _5];
+// return;
+// }
+// END rustc.node10.Deaggregator.before.mir
+// START rustc.node10.Deaggregator.after.mir
+// bb0: {
+// _2 = _1;
+// _4 = _2;
+// ((_3 as A).0: i32) = _4;
+// discriminant(_3) = 0;
+// _6 = _2;
+// ((_5 as A).0: i32) = _6;
+// discriminant(_5) = 0;
+// _0 = [_3, _5];
+// return;
+// }
+// END rustc.node10.Deaggregator.after.mir