Add tests.

Author: cjgillot

tests/mir-opt/jump_threading.rs

@@ -77,6 +77,32 @@ fn identity(x: Result<i32, i32>) -> Result<i32, i32> {
     Ok(x?)
 }
 
+fn two_reads() -> i32 {
+    // CHECK-LABEL: fn two_reads(
+    // CHECK: debug a => [[a:_.*]];
+    // CHECK: debug b => [[b:_.*]];
+    // CHECK: debug c => [[c:_.*]];
+    // CHECK: bb0: {
+    // CHECK:     [[a]] = const 2_i32;
+    // CHECK:     [[b]] = copy [[a]];
+    // CHECK:     [[c]] = copy [[a]];
+    // CHECK:     [[tmp:_.*]] = copy [[c]];
+    // CHECK:     [[eq:_.*]] = Eq(move [[tmp]], const 2_i32);
+    // CHECK:     switchInt(move [[eq]]) -> [0: bb2, otherwise: bb1];
+    // CHECK: bb1: {
+    // CHECK:     _0 = const 0_i32;
+    // CHECK:     goto -> bb3;
+    // CHECK: bb2: {
+    // CHECK:     _0 = const 1_i32;
+    // CHECK:     goto -> bb3;
+    // CHECK: bb3: {
+    // CHECK:     return;
+    let a = 2;
+    let b = a;
+    let c = a;
+    if c == 2 { 0 } else { 1 }
+}
+
 enum DFA {
     A,
     B,
@@ -599,6 +625,7 @@ fn main() {
 
 // EMIT_MIR jump_threading.too_complex.JumpThreading.diff
 // EMIT_MIR jump_threading.identity.JumpThreading.diff
+// EMIT_MIR jump_threading.two_reads.JumpThreading.diff
 // EMIT_MIR jump_threading.custom_discr.JumpThreading.diff
 // EMIT_MIR jump_threading.dfa.JumpThreading.diff
 // EMIT_MIR jump_threading.multiple_match.JumpThreading.diff

tests/mir-opt/jump_threading.two_reads.JumpThreading.panic-abort.diff

@@ -0,0 +1,55 @@
+- // MIR for `two_reads` before JumpThreading
++ // MIR for `two_reads` after JumpThreading
+  
+  fn two_reads() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _4: bool;
+      let mut _5: i32;
+      scope 1 {
+          debug a => _1;
+          let _2: i32;
+          scope 2 {
+              debug b => _2;
+              let _3: i32;
+              scope 3 {
+                  debug c => _3;
+              }
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          _1 = const 2_i32;
+          StorageLive(_2);
+          _2 = copy _1;
+          StorageLive(_3);
+          _3 = copy _1;
+          StorageLive(_4);
+          StorageLive(_5);
+          _5 = copy _3;
+          _4 = Eq(move _5, const 2_i32);
+          switchInt(move _4) -> [0: bb2, otherwise: bb1];
+      }
+  
+      bb1: {
+          StorageDead(_5);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+  
+      bb2: {
+          StorageDead(_5);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+  
+      bb3: {
+          StorageDead(_4);
+          StorageDead(_3);
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+  

tests/mir-opt/jump_threading.two_reads.JumpThreading.panic-unwind.diff

@@ -0,0 +1,55 @@
+- // MIR for `two_reads` before JumpThreading
++ // MIR for `two_reads` after JumpThreading
+  
+  fn two_reads() -> i32 {
+      let mut _0: i32;
+      let _1: i32;
+      let mut _4: bool;
+      let mut _5: i32;
+      scope 1 {
+          debug a => _1;
+          let _2: i32;
+          scope 2 {
+              debug b => _2;
+              let _3: i32;
+              scope 3 {
+                  debug c => _3;
+              }
+          }
+      }
+  
+      bb0: {
+          StorageLive(_1);
+          _1 = const 2_i32;
+          StorageLive(_2);
+          _2 = copy _1;
+          StorageLive(_3);
+          _3 = copy _1;
+          StorageLive(_4);
+          StorageLive(_5);
+          _5 = copy _3;
+          _4 = Eq(move _5, const 2_i32);
+          switchInt(move _4) -> [0: bb2, otherwise: bb1];
+      }
+  
+      bb1: {
+          StorageDead(_5);
+          _0 = const 0_i32;
+          goto -> bb3;
+      }
+  
+      bb2: {
+          StorageDead(_5);
+          _0 = const 1_i32;
+          goto -> bb3;
+      }
+  
+      bb3: {
+          StorageDead(_4);
+          StorageDead(_3);
+          StorageDead(_2);
+          StorageDead(_1);
+          return;
+      }
+  }
+