Auto merge of #108872 - cjgillot:simp-const-prop, r=oli-obk

Strengthen state tracking in const-prop

Some/many of the changes are replicated between both the const-prop lint and the const-prop optimization.

Behaviour changes:
- const-prop opt does not give a span to propagated values. This was useless as that span's primary purpose is to diagnose evaluation failure in codegen.
- we remove the `OnlyPropagateInto` mode. It was only used for function arguments, which are better modeled by a write before entry.
- the tracking of assignments and discriminants make clearer that we do nothing in `NoPropagation` mode or on indirect places.

6 files changed, 17 insertions, 15 deletions

diff --git a/tests/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff b/tests/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff
index ae9ffd519a1..bedfa5992ad 100644
--- a/tests/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff
+++ b/tests/mir-opt/const_prop/bad_op_mod_by_zero.main.ConstProp.diff
@@ -27,17 +27,19 @@
       }
   
       bb1: {
-          _5 = Eq(_1, const -1_i32);       // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
+-         _5 = Eq(_1, const -1_i32);       // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
 -         _6 = Eq(const 1_i32, const i32::MIN); // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
 -         _7 = BitAnd(move _5, move _6);   // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
 -         assert(!move _7, "attempt to compute the remainder of `{} % {}`, which would overflow", const 1_i32, _1) -> bb2; // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
++         _5 = const false;                // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
 +         _6 = const false;                // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
 +         _7 = const false;                // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
-+         assert(!const false, "attempt to compute the remainder of `{} % {}`, which would overflow", const 1_i32, _1) -> bb2; // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
++         assert(!const false, "attempt to compute the remainder of `{} % {}`, which would overflow", const 1_i32, const 0_i32) -> bb2; // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
       }
   
       bb2: {
-          _2 = Rem(const 1_i32, _1);       // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
+-         _2 = Rem(const 1_i32, _1);       // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
++         _2 = Rem(const 1_i32, const 0_i32); // scope 1 at $DIR/bad_op_mod_by_zero.rs:+2:14: +2:19
           StorageDead(_2);                 // scope 1 at $DIR/bad_op_mod_by_zero.rs:+3:1: +3:2
           return;                          // scope 0 at $DIR/bad_op_mod_by_zero.rs:+3:2: +3:2
       }
diff --git a/tests/mir-opt/const_prop/discriminant.main.ConstProp.32bit.diff b/tests/mir-opt/const_prop/discriminant.main.ConstProp.32bit.diff
index b9a10704be0..6d8738aa61a 100644
--- a/tests/mir-opt/const_prop/discriminant.main.ConstProp.32bit.diff
+++ b/tests/mir-opt/const_prop/discriminant.main.ConstProp.32bit.diff
@@ -22,7 +22,7 @@
 -         switchInt(move _4) -> [1: bb1, otherwise: bb3]; // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
 +         _3 = const Option::<bool>::Some(true); // scope 2 at $DIR/discriminant.rs:+1:34: +1:44
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:12:34: 12:44
++                                          // + span: no-location
 +                                          // + literal: Const { ty: Option<bool>, val: Value(Scalar(0x01)) }
 +         _4 = const 1_isize;              // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
 +         switchInt(const 1_isize) -> [1: bb1, otherwise: bb3]; // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
diff --git a/tests/mir-opt/const_prop/discriminant.main.ConstProp.64bit.diff b/tests/mir-opt/const_prop/discriminant.main.ConstProp.64bit.diff
index b9a10704be0..6d8738aa61a 100644
--- a/tests/mir-opt/const_prop/discriminant.main.ConstProp.64bit.diff
+++ b/tests/mir-opt/const_prop/discriminant.main.ConstProp.64bit.diff
@@ -22,7 +22,7 @@
 -         switchInt(move _4) -> [1: bb1, otherwise: bb3]; // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
 +         _3 = const Option::<bool>::Some(true); // scope 2 at $DIR/discriminant.rs:+1:34: +1:44
 +                                          // mir::Constant
-+                                          // + span: $DIR/discriminant.rs:12:34: 12:44
++                                          // + span: no-location
 +                                          // + literal: Const { ty: Option<bool>, val: Value(Scalar(0x01)) }
 +         _4 = const 1_isize;              // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
 +         switchInt(const 1_isize) -> [1: bb1, otherwise: bb3]; // scope 2 at $DIR/discriminant.rs:+1:21: +1:31
diff --git a/tests/mir-opt/const_prop/invalid_constant.main.ConstProp.diff b/tests/mir-opt/const_prop/invalid_constant.main.ConstProp.diff
index 4f056dd85e3..a38c1de2a78 100644
--- a/tests/mir-opt/const_prop/invalid_constant.main.ConstProp.diff
+++ b/tests/mir-opt/const_prop/invalid_constant.main.ConstProp.diff
@@ -44,11 +44,11 @@
 -         _3 = [move _4];                  // scope 1 at $DIR/invalid_constant.rs:+13:24: +13:60
 +         _4 = const Scalar(0x00000004): E; // scope 4 at $DIR/invalid_constant.rs:+13:34: +13:57
 +                                          // mir::Constant
-+                                          // + span: $DIR/invalid_constant.rs:28:34: 28:57
++                                          // + span: no-location
 +                                          // + literal: Const { ty: E, val: Value(Scalar(0x00000004)) }
 +         _3 = [const Scalar(0x00000004): E]; // scope 1 at $DIR/invalid_constant.rs:+13:24: +13:60
 +                                          // mir::Constant
-+                                          // + span: $DIR/invalid_constant.rs:28:24: 28:60
++                                          // + span: no-location
 +                                          // + literal: Const { ty: E, val: Value(Scalar(0x00000004)) }
           StorageDead(_4);                 // scope 1 at $DIR/invalid_constant.rs:+13:59: +13:60
           StorageDead(_5);                 // scope 1 at $DIR/invalid_constant.rs:+13:60: +13:61
diff --git a/tests/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff b/tests/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
index 1f5c533815d..ec063294856 100644
--- a/tests/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
+++ b/tests/mir-opt/funky_arms.float_to_exponential_common.ConstProp.diff
@@ -54,7 +54,7 @@
 -         _6 = MinusPlus;                  // scope 1 at $DIR/funky_arms.rs:+10:17: +10:41
 +         _6 = const MinusPlus;            // scope 1 at $DIR/funky_arms.rs:+10:17: +10:41
 +                                          // mir::Constant
-+                                          // + span: $DIR/funky_arms.rs:21:17: 21:41
++                                          // + span: no-location
 +                                          // + literal: Const { ty: Sign, val: Value(Scalar(0x01)) }
           goto -> bb4;                     // scope 1 at $DIR/funky_arms.rs:+10:17: +10:41
       }
@@ -63,7 +63,7 @@
 -         _6 = Minus;                      // scope 1 at $DIR/funky_arms.rs:+9:18: +9:38
 +         _6 = const Minus;                // scope 1 at $DIR/funky_arms.rs:+9:18: +9:38
 +                                          // mir::Constant
-+                                          // + span: $DIR/funky_arms.rs:20:18: 20:38
++                                          // + span: no-location
 +                                          // + literal: Const { ty: Sign, val: Value(Scalar(0x00)) }
           goto -> bb4;                     // scope 1 at $DIR/funky_arms.rs:+9:18: +9:38
       }
diff --git a/tests/ui/consts/const-err-late.stderr b/tests/ui/consts/const-err-late.stderr
index cb0cab2444b..192b9ba204b 100644
--- a/tests/ui/consts/const-err-late.stderr
+++ b/tests/ui/consts/const-err-late.stderr
@@ -10,12 +10,6 @@ note: erroneous constant used
 LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
    |                ^^^^^^^^^^^^^
 
-note: erroneous constant used
-  --> $DIR/const-err-late.rs:19:16
-   |
-LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
-   |                ^^^^^^^^^^^^^
-
 error[E0080]: evaluation of `S::<u32>::FOO` failed
   --> $DIR/const-err-late.rs:13:21
    |
@@ -34,6 +28,12 @@ note: erroneous constant used
 LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
    |                ^^^^^^^^^^^^^
 
+note: erroneous constant used
+  --> $DIR/const-err-late.rs:19:16
+   |
+LL |     black_box((S::<i32>::FOO, S::<u32>::FOO));
+   |                ^^^^^^^^^^^^^
+
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.