coverage: Use -Copt-level=2 by default in run-coverage tests

This is a step towards being able to unify the two coverage test directories.

There are two tests that require adjustment:

- `overflow.rs` requires an explicit `-Coverflow-checks=yes`
- `sort_groups.rs` is sensitive to provably unused instantiations

Author: Zalathar

src/tools/compiletest/src/runtest.rs

@@ -2481,9 +2481,9 @@ impl<'test> TestCx<'test> {
             RunCoverage => {
                 rustc.arg("-Cinstrument-coverage");
                 // Coverage reports are sometimes sensitive to optimizations,
-                // and the current snapshots assume no optimization unless
+                // and the current snapshots assume `opt-level=2` unless
                 // overridden by `compile-flags`.
-                rustc.arg("-Copt-level=0");
+                rustc.arg("-Copt-level=2");
             }
             RunPassValgrind | Pretty | DebugInfo | Codegen | Rustdoc | RustdocJson | RunMake
             | CodegenUnits | JsDocTest | Assembly => {

tests/coverage-map/status-quo/overflow.cov-map

@@ -1,5 +1,5 @@
 Function name: overflow::main
-Raw bytes (65): 0x[01, 01, 08, 01, 1b, 05, 1f, 09, 0d, 03, 11, 16, 05, 03, 11, 05, 1f, 09, 0d, 09, 01, 0f, 01, 01, 1b, 03, 02, 0b, 00, 18, 16, 01, 0c, 00, 1a, 05, 00, 1b, 03, 0a, 12, 03, 13, 00, 20, 09, 00, 21, 03, 0a, 0d, 03, 0a, 00, 0b, 1b, 01, 09, 00, 17, 11, 02, 05, 01, 02]
+Raw bytes (65): 0x[01, 01, 08, 01, 1b, 05, 1f, 09, 0d, 03, 11, 16, 05, 03, 11, 05, 1f, 09, 0d, 09, 01, 10, 01, 01, 1b, 03, 02, 0b, 00, 18, 16, 01, 0c, 00, 1a, 05, 00, 1b, 03, 0a, 12, 03, 13, 00, 20, 09, 00, 21, 03, 0a, 0d, 03, 0a, 00, 0b, 1b, 01, 09, 00, 17, 11, 02, 05, 01, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 8
@@ -12,7 +12,7 @@ Number of expressions: 8
 - expression 6 operands: lhs = Counter(1), rhs = Expression(7, Add)
 - expression 7 operands: lhs = Counter(2), rhs = Counter(3)
 Number of file 0 mappings: 9
-- Code(Counter(0)) at (prev + 15, 1) to (start + 1, 27)
+- Code(Counter(0)) at (prev + 16, 1) to (start + 1, 27)
 - Code(Expression(0, Add)) at (prev + 2, 11) to (start + 0, 24)
     = (c0 + (c1 + (c2 + c3)))
 - Code(Expression(5, Sub)) at (prev + 1, 12) to (start + 0, 26)
@@ -27,14 +27,14 @@ Number of file 0 mappings: 9
 - Code(Counter(4)) at (prev + 2, 5) to (start + 1, 2)
 
 Function name: overflow::might_overflow
-Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 04, 01, 01, 12, 05, 01, 13, 02, 06, 02, 02, 06, 00, 07, 07, 01, 09, 05, 02]
+Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 05, 01, 01, 12, 05, 01, 13, 02, 06, 02, 02, 06, 00, 07, 07, 01, 09, 05, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 2
 - expression 0 operands: lhs = Counter(0), rhs = Counter(1)
 - expression 1 operands: lhs = Counter(1), rhs = Expression(0, Sub)
 Number of file 0 mappings: 4
-- Code(Counter(0)) at (prev + 4, 1) to (start + 1, 18)
+- Code(Counter(0)) at (prev + 5, 1) to (start + 1, 18)
 - Code(Counter(1)) at (prev + 1, 19) to (start + 2, 6)
 - Code(Expression(0, Sub)) at (prev + 2, 6) to (start + 0, 7)
     = (c0 - c1)

tests/coverage-map/status-quo/overflow.rs

@@ -1,4 +1,5 @@
 #![allow(unused_assignments)]
+// compile-flags: -Coverflow-checks=yes
 // failure-status: 101
 
 fn might_overflow(to_add: u32) -> u32 {

tests/coverage-map/status-quo/sort_groups.cov-map

@@ -28,6 +28,21 @@ Number of file 0 mappings: 4
 - Code(Expression(1, Add)) at (prev + 1, 1) to (start + 0, 2)
     = (c1 + (c0 - c1))
 
+Function name: sort_groups::generic_fn::<char>
+Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 11, 01, 01, 0c, 05, 01, 0d, 02, 06, 02, 02, 06, 00, 07, 07, 01, 01, 00, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 2
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Expression(0, Sub)
+Number of file 0 mappings: 4
+- Code(Counter(0)) at (prev + 17, 1) to (start + 1, 12)
+- Code(Counter(1)) at (prev + 1, 13) to (start + 2, 6)
+- Code(Expression(0, Sub)) at (prev + 2, 6) to (start + 0, 7)
+    = (c0 - c1)
+- Code(Expression(1, Add)) at (prev + 1, 1) to (start + 0, 2)
+    = (c1 + (c0 - c1))
+
 Function name: sort_groups::generic_fn::<i32>
 Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 11, 01, 01, 0c, 05, 01, 0d, 02, 06, 02, 02, 06, 00, 07, 07, 01, 01, 00, 02]
 Number of files: 1
@@ -44,19 +59,19 @@ Number of file 0 mappings: 4
     = (c1 + (c0 - c1))
 
 Function name: sort_groups::main
-Raw bytes (28): 0x[01, 01, 02, 01, 00, 00, 02, 04, 01, 06, 01, 04, 0d, 00, 04, 0e, 02, 06, 02, 02, 06, 00, 07, 07, 01, 05, 02, 02]
+Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 06, 01, 04, 23, 05, 04, 24, 02, 06, 02, 02, 06, 00, 07, 07, 01, 05, 02, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 2
-- expression 0 operands: lhs = Counter(0), rhs = Zero
-- expression 1 operands: lhs = Zero, rhs = Expression(0, Sub)
+- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
+- expression 1 operands: lhs = Counter(1), rhs = Expression(0, Sub)
 Number of file 0 mappings: 4
-- Code(Counter(0)) at (prev + 6, 1) to (start + 4, 13)
-- Code(Zero) at (prev + 4, 14) to (start + 2, 6)
+- Code(Counter(0)) at (prev + 6, 1) to (start + 4, 35)
+- Code(Counter(1)) at (prev + 4, 36) to (start + 2, 6)
 - Code(Expression(0, Sub)) at (prev + 2, 6) to (start + 0, 7)
-    = (c0 - Zero)
+    = (c0 - c1)
 - Code(Expression(1, Add)) at (prev + 1, 5) to (start + 2, 2)
-    = (Zero + (c0 - Zero))
+    = (c1 + (c0 - c1))
 
 Function name: sort_groups::other_fn
 Raw bytes (9): 0x[01, 01, 00, 01, 01, 17, 01, 00, 11]

tests/coverage-map/status-quo/sort_groups.rs

@@ -7,7 +7,7 @@ fn main() {
     let cond = std::env::args().len() > 1;
     generic_fn::<()>(cond);
     generic_fn::<&'static str>(!cond);
-    if false {
+    if std::hint::black_box(false) {
         generic_fn::<char>(cond);
     }
     generic_fn::<i32>(cond);

tests/run-coverage/overflow.coverage

@@ -1,4 +1,5 @@
    LL|       |#![allow(unused_assignments)]
+   LL|       |// compile-flags: -Coverflow-checks=yes
    LL|       |// failure-status: 101
    LL|       |
    LL|      4|fn might_overflow(to_add: u32) -> u32 {

tests/run-coverage/overflow.rs

@@ -1,4 +1,5 @@
 #![allow(unused_assignments)]
+// compile-flags: -Coverflow-checks=yes
 // failure-status: 101
 
 fn might_overflow(to_add: u32) -> u32 {

tests/run-coverage/sort_groups.coverage

@@ -7,7 +7,7 @@
    LL|      1|    let cond = std::env::args().len() > 1;
    LL|      1|    generic_fn::<()>(cond);
    LL|      1|    generic_fn::<&'static str>(!cond);
-   LL|      1|    if false {
+   LL|      1|    if std::hint::black_box(false) {
    LL|      0|        generic_fn::<char>(cond);
    LL|      1|    }
    LL|      1|    generic_fn::<i32>(cond);

tests/run-coverage/sort_groups.rs

@@ -7,7 +7,7 @@ fn main() {
     let cond = std::env::args().len() > 1;
     generic_fn::<()>(cond);
     generic_fn::<&'static str>(!cond);
-    if false {
+    if std::hint::black_box(false) {
         generic_fn::<char>(cond);
     }
     generic_fn::<i32>(cond);