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| author | bors <bors@rust-lang.org> | 2020-10-21 17:44:48 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2020-10-21 17:44:48 +0000 |
| commit | 1d2726726f8f3128e98191e4c6cb94bd76d0ddd4 (patch) | |
| tree | 4df0f66fa5beaeb1ea7e813d33d0736ba0c17fe4 | |
| parent | 22e6b9c68941996daa45786b4145e6196e51f0f4 (diff) | |
| parent | e200a4a0d21473de9cc8ff817a0e4eba304e7e69 (diff) | |
| download | rust-1d2726726f8f3128e98191e4c6cb94bd76d0ddd4.tar.gz rust-1d2726726f8f3128e98191e4c6cb94bd76d0ddd4.zip | |
Auto merge of #78195 - tmiasko:instcombine, r=jonas-schievink
Disable "optimization to avoid load of address" in InstCombine The transformation is incorrect #78192. Disable it.
4 files changed, 8 insertions, 3 deletions
diff --git a/compiler/rustc_mir/src/transform/instcombine.rs b/compiler/rustc_mir/src/transform/instcombine.rs index 1a8e281d417..c0b3d5ff18b 100644 --- a/compiler/rustc_mir/src/transform/instcombine.rs +++ b/compiler/rustc_mir/src/transform/instcombine.rs @@ -119,6 +119,11 @@ impl OptimizationFinder<'b, 'tcx> { } fn find_deref_of_address(&mut self, rvalue: &Rvalue<'tcx>, location: Location) -> Option<()> { + // FIXME(#78192): This optimization can result in unsoundness. + if !self.tcx.sess.opts.debugging_opts.unsound_mir_opts { + return None; + } + // Look for the sequence // // _2 = &_1; diff --git a/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff b/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff index feef65f52eb..4fd1b8b2276 100644 --- a/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/ref_deref.main.ConstProp.diff @@ -19,7 +19,7 @@ // + span: $DIR/ref_deref.rs:5:6: 5:10 // + literal: Const { ty: &i32, val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref[317d]::main), const_param_did: None }, [], Some(promoted[0])) } _2 = _4; // scope 0 at $DIR/ref_deref.rs:5:6: 5:10 -- _1 = (*_4); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 +- _1 = (*_2); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 + _1 = const 4_i32; // scope 0 at $DIR/ref_deref.rs:5:5: 5:10 StorageDead(_2); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11 StorageDead(_1); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11 diff --git a/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff b/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff index 7ec0751263f..812c7c97718 100644 --- a/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff +++ b/src/test/mir-opt/const_prop/ref_deref_project.main.ConstProp.diff @@ -19,7 +19,7 @@ // + span: $DIR/ref_deref_project.rs:5:6: 5:17 // + literal: Const { ty: &(i32, i32), val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref_project[317d]::main), const_param_did: None }, [], Some(promoted[0])) } _2 = &((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:6: 5:17 - _1 = ((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17 + _1 = (*_2); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17 StorageDead(_2); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18 StorageDead(_1); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18 _0 = const (); // scope 0 at $DIR/ref_deref_project.rs:4:11: 6:2 diff --git a/src/test/mir-opt/inst_combine_deref.rs b/src/test/mir-opt/inst_combine_deref.rs index 3be8c2f3ac7..78361c33660 100644 --- a/src/test/mir-opt/inst_combine_deref.rs +++ b/src/test/mir-opt/inst_combine_deref.rs @@ -1,4 +1,4 @@ -// compile-flags: -O +// compile-flags: -O -Zunsound-mir-opts // EMIT_MIR inst_combine_deref.simple_opt.InstCombine.diff fn simple_opt() -> u64 { let x = 5; |