Rollup merge of #131203 - clubby789:jumpthreading-not, r=compiler-errors

JumpThreading: fix bitwise not on non-booleans Fixes #131195 Alternative to #131201
rust-lang · Oct 3, 2024 · 1ce9d8d · 1ce9d8d
2 parents 36b7052 + fd35e82
commit 1ce9d8d
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Showing 6 changed files with 127 additions and 12 deletions.
diff --git a/compiler/rustc_middle/src/ty/consts/int.rs b/compiler/rustc_middle/src/ty/consts/int.rs
@@ -398,6 +398,11 @@ impl ScalarInt {
     pub fn to_f128(self) -> Quad {
         self.to_float()
     }
+
+    #[inline]
+    pub fn bitwise_not(self) -> Self {
+        Self { data: self.size().truncate(!self.data), size: self.size }
+    }
 }
 
 macro_rules! from_x_for_scalar_int {

diff --git a/compiler/rustc_mir_transform/src/jump_threading.rs b/compiler/rustc_mir_transform/src/jump_threading.rs
@@ -150,10 +150,8 @@ impl Condition {
     }
 
     fn inv(mut self) -> Self {
-        self.polarity = match self.polarity {
-            Polarity::Eq => Polarity::Ne,
-            Polarity::Ne => Polarity::Eq,
-        };
+        self.value = self.value.bitwise_not();
+
         self
     }
 }

diff --git a/tests/mir-opt/jump_threading.not_int.JumpThreading.panic-abort.diff b/tests/mir-opt/jump_threading.not_int.JumpThreading.panic-abort.diff
@@ -0,0 +1,46 @@
+- // MIR for `not_int` before JumpThreading
++ // MIR for `not_int` after JumpThreading
+
+  fn not_int() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _2: bool;
+      let mut _3: i32;
+      let mut _4: i32;
+      scope 1 {
+          debug a => _1;
+      }
+
+      bb0: {
+          StorageLive(_1);
+          _1 = const 1_i32;
+          StorageLive(_2);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = copy _1;
+          _3 = Not(move _4);
+          StorageDead(_4);
+          _2 = Eq(move _3, const 0_i32);
+-         switchInt(move _2) -> [0: bb2, otherwise: bb1];
++         goto -> bb2;
+      }
+
+      bb1: {
+          StorageDead(_3);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+
+      bb2: {
+          StorageDead(_3);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+
+      bb3: {
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+
diff --git a/tests/mir-opt/jump_threading.not_int.JumpThreading.panic-unwind.diff b/tests/mir-opt/jump_threading.not_int.JumpThreading.panic-unwind.diff
@@ -0,0 +1,46 @@
+- // MIR for `not_int` before JumpThreading
++ // MIR for `not_int` after JumpThreading
+
+  fn not_int() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _2: bool;
+      let mut _3: i32;
+      let mut _4: i32;
+      scope 1 {
+          debug a => _1;
+      }
+
+      bb0: {
+          StorageLive(_1);
+          _1 = const 1_i32;
+          StorageLive(_2);
+          StorageLive(_3);
+          StorageLive(_4);
+          _4 = copy _1;
+          _3 = Not(move _4);
+          StorageDead(_4);
+          _2 = Eq(move _3, const 0_i32);
+-         switchInt(move _2) -> [0: bb2, otherwise: bb1];
++         goto -> bb2;
+      }
+
+      bb1: {
+          StorageDead(_3);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+
+      bb2: {
+          StorageDead(_3);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+
+      bb3: {
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+
diff --git a/tests/mir-opt/jump_threading.rs b/tests/mir-opt/jump_threading.rs
@@ -531,6 +531,21 @@ fn floats() -> u32 {
     if x == 0.0 { 0 } else { 1 }
 }
 
+fn not_int() -> i32 {
+    // CHECK-LABEL: fn not_int(
+    // CHECK: goto -> bb2
+
+    // CHECK-LABEL: bb1: {
+    // _0 = const 1_i32;
+
+    // CHECK-LABEL: bb2: {
+    // _0 = const 0_i32;
+    // Test for issue #131195, where !a == b is assumed to be equivalent to a != b
+    // This is only the case for bools
+    let a = 1;
+    if !a == 0 { 1 } else { 0 }
+}
+
 fn main() {
     // CHECK-LABEL: fn main(
     too_complex(Ok(0));
@@ -546,6 +561,7 @@ fn main() {
     aggregate(7);
     assume(7, false);
     floats();
+    not_int();
 }
 
 // EMIT_MIR jump_threading.too_complex.JumpThreading.diff
@@ -562,3 +578,4 @@ fn main() {
 // EMIT_MIR jump_threading.assume.JumpThreading.diff
 // EMIT_MIR jump_threading.aggregate_copy.JumpThreading.diff
 // EMIT_MIR jump_threading.floats.JumpThreading.diff
+// EMIT_MIR jump_threading.not_int.JumpThreading.diff
diff --git a/tests/mir-opt/pre-codegen/checked_ops.step_forward.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/checked_ops.step_forward.PreCodegen.after.panic-unwind.mir
@@ -33,7 +33,7 @@ fn step_forward(_1: u16, _2: usize) -> u16 {
         StorageLive(_4);
         StorageLive(_3);
         _3 = Gt(copy _2, const 65535_usize);
-        switchInt(move _3) -> [0: bb1, otherwise: bb5];
+        switchInt(move _3) -> [0: bb1, otherwise: bb6];
     }
 
     bb1: {
@@ -54,27 +54,30 @@ fn step_forward(_1: u16, _2: usize) -> u16 {
     bb3: {
         StorageDead(_5);
         StorageDead(_6);
-        StorageDead(_7);
-        goto -> bb7;
+        goto -> bb5;
     }
 
     bb4: {
         StorageDead(_5);
         StorageDead(_6);
-        StorageDead(_7);
-        goto -> bb6;
+        goto -> bb5;
     }
 
     bb5: {
-        StorageDead(_3);
-        goto -> bb6;
+        StorageDead(_7);
+        goto -> bb7;
     }
 
     bb6: {
-        assert(!const true, "attempt to compute `{} + {}`, which would overflow", const core::num::<impl u16>::MAX, const 1_u16) -> [success: bb7, unwind continue];
+        StorageDead(_3);
+        goto -> bb7;
     }
 
     bb7: {
+        assert(!const true, "attempt to compute `{} + {}`, which would overflow", const core::num::<impl u16>::MAX, const 1_u16) -> [success: bb8, unwind continue];
+    }
+
+    bb8: {
         StorageLive(_8);
         _8 = copy _2 as u16 (IntToInt);
         _0 = Add(copy _1, copy _8);