fix ConstProp handling of written_only_inside_own_block_locals

diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
index 53f33a7a0bad2516cde21120e629806b0898fa09..7a2a15a84a358fcef611df7b8f9f164ec81a6fb3 100644 (file)
--- a/compiler/rustc_mir_transform/src/const_prop.rs
+++ b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -1066,32 +1066,32 @@ fn visit_terminator(&mut self, terminator: &mut Terminator<'tcx>, location: Loca
         let source_info = terminator.source_info;
         self.source_info = Some(source_info);
         self.super_terminator(terminator, location);
+        // Do NOT early return in this function, it does some crucial fixup of the state at the end!
         match &mut terminator.kind {
             TerminatorKind::Assert { expected, ref mut cond, .. } => {
                 if let Some(ref value) = self.eval_operand(&cond) {
                     trace!("assertion on {:?} should be {:?}", value, expected);
                     let expected = Scalar::from_bool(*expected);
-                    let Ok(value_const) = self.ecx.read_scalar(&value) else {
-                        // FIXME should be used use_ecx rather than a local match... but we have
-                        // quite a few of these read_scalar/read_immediate that need fixing.
-                        return
-                    };
-                    if expected != value_const {
-                        // Poison all places this operand references so that further code
-                        // doesn't use the invalid value
-                        match cond {
-                            Operand::Move(ref place) | Operand::Copy(ref place) => {
-                                Self::remove_const(&mut self.ecx, place.local);
+                    // FIXME should be used use_ecx rather than a local match... but we have
+                    // quite a few of these read_scalar/read_immediate that need fixing.
+                    if let Ok(value_const) = self.ecx.read_scalar(&value) {
+                        if expected != value_const {
+                            // Poison all places this operand references so that further code
+                            // doesn't use the invalid value
+                            match cond {
+                                Operand::Move(ref place) | Operand::Copy(ref place) => {
+                                    Self::remove_const(&mut self.ecx, place.local);
+                                }
+                                Operand::Constant(_) => {}
+                            }
+                        } else {
+                            if self.should_const_prop(value) {
+                                *cond = self.operand_from_scalar(
+                                    value_const,
+                                    self.tcx.types.bool,
+                                    source_info.span,
+                                );
                             }
-                            Operand::Constant(_) => {}
-                        }
-                    } else {
-                        if self.should_const_prop(value) {
-                            *cond = self.operand_from_scalar(
-                                value_const,
-                                self.tcx.types.bool,
-                                source_info.span,
-                            );
                         }
                     }
                 }

diff --git a/src/test/mir-opt/issue-101973.rs b/src/test/mir-opt/issue-101973.rs
new file mode 100644 (file)
index 0000000..216659a
--- /dev/null
+++ b/src/test/mir-opt/issue-101973.rs
@@ -0,0 +1,20 @@
+// compile-flags: -O -C debug-assertions=on
+// This needs inlining followed by ConstProp to reproduce, so we cannot use "unit-test".
+
+#[inline]
+pub fn imm8(x: u32) -> u32 {
+    let mut out = 0u32;
+    out |= (x >> 0) & 0xff;
+    out
+}
+
+// EMIT_MIR issue_101973.inner.ConstProp.diff
+#[inline(never)]
+pub fn inner(fields: u32) -> i64 {
+    imm8(fields).rotate_right(((fields >> 8) & 0xf) << 1) as i32 as i64
+}
+
+fn main() {
+    let val = inner(0xe32cf20f);
+    assert_eq!(val as u64, 0xfffffffff0000000);
+}

diff --git a/src/test/mir-opt/issue_101973.inner.ConstProp.diff b/src/test/mir-opt/issue_101973.inner.ConstProp.diff
new file mode 100644 (file)
index 0000000..89733a9
--- /dev/null
+++ b/src/test/mir-opt/issue_101973.inner.ConstProp.diff
@@ -0,0 +1,100 @@
+- // MIR for `inner` before ConstProp
++ // MIR for `inner` after ConstProp
+  
+  fn inner(_1: u32) -> i64 {
+      debug fields => _1;                  // in scope 0 at $DIR/issue-101973.rs:+0:14: +0:20
+      let mut _0: i64;                     // return place in scope 0 at $DIR/issue-101973.rs:+0:30: +0:33
+      let mut _2: i32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+      let mut _3: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:58
+      let mut _4: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:17
+      let mut _5: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+      let mut _6: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      let mut _7: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+      let mut _8: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      let mut _9: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+      let mut _10: (u32, bool);            // in scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      let mut _11: (u32, bool);            // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      scope 1 (inlined imm8) {             // at $DIR/issue-101973.rs:14:5: 14:17
+          debug x => _5;                   // in scope 1 at $DIR/issue-101973.rs:5:13: 5:14
+          let mut _12: u32;                // in scope 1 at $DIR/issue-101973.rs:7:12: 7:27
+          let mut _13: u32;                // in scope 1 at $DIR/issue-101973.rs:7:12: 7:20
+          let mut _14: u32;                // in scope 1 at $DIR/issue-101973.rs:7:13: 7:14
+          let mut _15: (u32, bool);        // in scope 1 at $DIR/issue-101973.rs:7:12: 7:20
+          scope 2 {
+              debug out => _4;             // in scope 2 at $DIR/issue-101973.rs:6:9: 6:16
+          }
+      }
+      scope 3 (inlined core::num::<impl u32>::rotate_right) { // at $DIR/issue-101973.rs:14:5: 14:58
+          debug self => _4;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          debug n => _6;                   // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          let mut _16: u32;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          let mut _17: u32;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+      }
+  
+      bb0: {
+          StorageLive(_2);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+          StorageLive(_3);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:58
+          StorageLive(_4);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:17
+          StorageLive(_5);                 // scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+          _5 = _1;                         // scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+          _4 = const 0_u32;                // scope 1 at $DIR/issue-101973.rs:6:19: 6:23
+          StorageLive(_12);                // scope 2 at $DIR/issue-101973.rs:7:12: 7:27
+          StorageLive(_13);                // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          StorageLive(_14);                // scope 2 at $DIR/issue-101973.rs:7:13: 7:14
+          _14 = _5;                        // scope 2 at $DIR/issue-101973.rs:7:13: 7:14
+          _15 = CheckedShr(_14, const 0_i32); // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          assert(!move (_15.1: bool), "attempt to shift right by `{}`, which would overflow", const 0_i32) -> bb3; // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+      }
+  
+      bb1: {
+          _8 = move (_10.0: u32);          // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          StorageDead(_9);                 // scope 0 at $DIR/issue-101973.rs:+1:44: +1:45
+          _7 = BitAnd(move _8, const 15_u32); // scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+          StorageDead(_8);                 // scope 0 at $DIR/issue-101973.rs:+1:51: +1:52
+          _11 = CheckedShl(_7, const 1_i32); // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          assert(!move (_11.1: bool), "attempt to shift left by `{}`, which would overflow", const 1_i32) -> bb2; // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      }
+  
+      bb2: {
+          _6 = move (_11.0: u32);          // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          StorageDead(_7);                 // scope 0 at $DIR/issue-101973.rs:+1:56: +1:57
+          StorageLive(_16);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _16 = _4;                        // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageLive(_17);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _17 = _6;                        // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _3 = rotate_right::<u32>(move _16, move _17) -> bb4; // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+                                           // + literal: Const { ty: extern "rust-intrinsic" fn(u32, u32) -> u32 {rotate_right::<u32>}, val: Value(<ZST>) }
+      }
+  
+      bb3: {
+          _13 = move (_15.0: u32);         // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          StorageDead(_14);                // scope 2 at $DIR/issue-101973.rs:7:19: 7:20
+          _12 = BitAnd(move _13, const 255_u32); // scope 2 at $DIR/issue-101973.rs:7:12: 7:27
+          StorageDead(_13);                // scope 2 at $DIR/issue-101973.rs:7:26: 7:27
+          _4 = BitOr(_4, move _12);        // scope 2 at $DIR/issue-101973.rs:7:5: 7:27
+          StorageDead(_12);                // scope 2 at $DIR/issue-101973.rs:7:26: 7:27
+          StorageDead(_5);                 // scope 0 at $DIR/issue-101973.rs:+1:16: +1:17
+          StorageLive(_6);                 // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          StorageLive(_7);                 // scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+          StorageLive(_8);                 // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          StorageLive(_9);                 // scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+          _9 = _1;                         // scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+          _10 = CheckedShr(_9, const 8_i32); // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          assert(!move (_10.1: bool), "attempt to shift right by `{}`, which would overflow", const 8_i32) -> bb1; // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      }
+  
+      bb4: {
+          StorageDead(_17);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageDead(_16);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageDead(_6);                 // scope 0 at $DIR/issue-101973.rs:+1:57: +1:58
+          StorageDead(_4);                 // scope 0 at $DIR/issue-101973.rs:+1:57: +1:58
+          _2 = move _3 as i32 (Misc);      // scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+          StorageDead(_3);                 // scope 0 at $DIR/issue-101973.rs:+1:64: +1:65
+          _0 = move _2 as i64 (Misc);      // scope 0 at $DIR/issue-101973.rs:+1:5: +1:72
+          StorageDead(_2);                 // scope 0 at $DIR/issue-101973.rs:+1:71: +1:72
+          return;                          // scope 0 at $DIR/issue-101973.rs:+2:2: +2:2
+      }
+  }
+