coverage: Harmonize the coverage-map and run-coverage test directories

src/tools/compiletest/src/runtest.rs

@@ -2193,7 +2193,7 @@ impl<'test> TestCx<'test> {
             || self.is_vxworks_pure_static()
             || self.config.target.contains("bpf")
             || !self.config.target_cfg().dynamic_linking
-            || self.config.mode == RunCoverage
+            || matches!(self.config.mode, CoverageMap | RunCoverage)
         {
             // We primarily compile all auxiliary libraries as dynamic libraries
             // to avoid code size bloat and large binaries as much as possible
@@ -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/README.md

@@ -1,4 +1,4 @@
-The tests in `./status-quo` were copied from `tests/run-coverage` in order to
+Many of these tests were copied from `tests/run-coverage` in order to
 capture the current behavior of the instrumentor on non-trivial programs.
 The actual mappings have not been closely inspected.
 

tests/coverage-map/auxiliary/inline_always_with_dead_code.rs

@@ -0,0 +1,22 @@
+// compile-flags: -Cinstrument-coverage -Ccodegen-units=4 -Copt-level=0
+
+#![allow(dead_code)]
+
+mod foo {
+    #[inline(always)]
+    pub fn called() {}
+
+    fn uncalled() {}
+}
+
+pub mod bar {
+    pub fn call_me() {
+        super::foo::called();
+    }
+}
+
+pub mod baz {
+    pub fn call_me() {
+        super::foo::called();
+    }
+}

tests/coverage-map/auxiliary/unused_mod_helper.rs

@@ -0,0 +1,4 @@
+#[allow(dead_code)]
+pub fn never_called_function() {
+    println!("I am never called");
+}

tests/coverage-map/auxiliary/used_crate.rs

@@ -0,0 +1,103 @@
+#![allow(unused_assignments, unused_variables)]
+// Verify that coverage works with optimizations:
+// compile-flags: -C opt-level=3
+
+use std::fmt::Debug;
+
+pub fn used_function() {
+    // Initialize test constants in a way that cannot be determined at compile time, to ensure
+    // rustc and LLVM cannot optimize out statements (or coverage counters) downstream from
+    // dependent conditions.
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 0;
+    if is_true {
+        countdown = 10;
+    }
+    use_this_lib_crate();
+}
+
+pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
+}
+// Expect for above function: `Unexecuted instantiation` (see below)
+pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
+}
+
+pub fn used_from_bin_crate_and_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_from_bin_crate_and_lib_crate_generic_function with {:?}", arg);
+}
+
+pub fn used_with_same_type_from_bin_crate_and_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_with_same_type_from_bin_crate_and_lib_crate_generic_function with {:?}", arg);
+}
+
+pub fn unused_generic_function<T: Debug>(arg: T) {
+    println!("unused_generic_function with {:?}", arg);
+}
+
+pub fn unused_function() {
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 2;
+    if !is_true {
+        countdown = 20;
+    }
+}
+
+#[allow(dead_code)]
+fn unused_private_function() {
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 2;
+    if !is_true {
+        countdown = 20;
+    }
+}
+
+fn use_this_lib_crate() {
+    used_from_bin_crate_and_lib_crate_generic_function("used from library used_crate.rs");
+    used_with_same_type_from_bin_crate_and_lib_crate_generic_function(
+        "used from library used_crate.rs",
+    );
+    let some_vec = vec![5, 6, 7, 8];
+    used_only_from_this_lib_crate_generic_function(some_vec);
+    used_only_from_this_lib_crate_generic_function("used ONLY from library used_crate.rs");
+}
+
+// FIXME(#79651): "Unexecuted instantiation" errors appear in coverage results,
+// for example:
+//
+// | Unexecuted instantiation: used_crate::used_only_from_bin_crate_generic_function::<_>
+//
+// These notices appear when `llvm-cov` shows instantiations. This may be a
+// default option, but it can be suppressed with:
+//
+// ```shell
+// $ `llvm-cov show --show-instantiations=0 ...`
+// ```
+//
+// The notice is triggered because the function is unused by the library itself,
+// and when the library is compiled, a synthetic function is generated, so
+// unused function coverage can be reported. Coverage can be skipped for unused
+// generic functions with:
+//
+// ```shell
+// $ `rustc -Zunstable-options -C instrument-coverage=except-unused-generics ...`
+// ```
+//
+// Even though this function is used by `uses_crate.rs` (and
+// counted), with substitutions for `T`, those instantiations are only generated
+// when the generic function is actually used (from the binary, not from this
+// library crate). So the test result shows coverage for all instantiated
+// versions and their generic type substitutions, plus the `Unexecuted
+// instantiation` message for the non-substituted version. This is valid, but
+// unfortunately a little confusing.
+//
+// The library crate has its own coverage map, and the only way to show unused
+// coverage of a generic function is to include the generic function in the
+// coverage map, marked as an "unused function". If the library were used by
+// another binary that never used this generic function, then it would be valid
+// to show the unused generic, with unknown substitution (`_`).
+//
+// The alternative is to exclude all generics from being included in the "unused
+// functions" list, which would then omit coverage results for
+// `unused_generic_function<T>()`, below.

tests/coverage-map/auxiliary/used_inline_crate.rs

@@ -0,0 +1,85 @@
+#![allow(unused_assignments, unused_variables)]
+// Verify that coverage works with optimizations:
+// compile-flags: -C opt-level=3
+
+use std::fmt::Debug;
+
+pub fn used_function() {
+    // Initialize test constants in a way that cannot be determined at compile time, to ensure
+    // rustc and LLVM cannot optimize out statements (or coverage counters) downstream from
+    // dependent conditions.
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 0;
+    if is_true {
+        countdown = 10;
+    }
+    use_this_lib_crate();
+}
+
+#[inline(always)]
+pub fn used_inline_function() {
+    // Initialize test constants in a way that cannot be determined at compile time, to ensure
+    // rustc and LLVM cannot optimize out statements (or coverage counters) downstream from
+    // dependent conditions.
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 0;
+    if is_true {
+        countdown = 10;
+    }
+    use_this_lib_crate();
+}
+
+#[inline(always)]
+pub fn used_only_from_bin_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_only_from_bin_crate_generic_function with {:?}", arg);
+}
+// Expect for above function: `Unexecuted instantiation` (see notes in `used_crate.rs`)
+
+#[inline(always)]
+pub fn used_only_from_this_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_only_from_this_lib_crate_generic_function with {:?}", arg);
+}
+
+#[inline(always)]
+pub fn used_from_bin_crate_and_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_from_bin_crate_and_lib_crate_generic_function with {:?}", arg);
+}
+
+#[inline(always)]
+pub fn used_with_same_type_from_bin_crate_and_lib_crate_generic_function<T: Debug>(arg: T) {
+    println!("used_with_same_type_from_bin_crate_and_lib_crate_generic_function with {:?}", arg);
+}
+
+#[inline(always)]
+pub fn unused_generic_function<T: Debug>(arg: T) {
+    println!("unused_generic_function with {:?}", arg);
+}
+
+#[inline(always)]
+pub fn unused_function() {
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 2;
+    if !is_true {
+        countdown = 20;
+    }
+}
+
+#[inline(always)]
+#[allow(dead_code)]
+fn unused_private_function() {
+    let is_true = std::env::args().len() == 1;
+    let mut countdown = 2;
+    if !is_true {
+        countdown = 20;
+    }
+}
+
+fn use_this_lib_crate() {
+    used_from_bin_crate_and_lib_crate_generic_function("used from library used_crate.rs");
+    used_with_same_type_from_bin_crate_and_lib_crate_generic_function(
+        "used from library used_crate.rs",
+    );
+    let some_vec = vec![5, 6, 7, 8];
+    used_only_from_this_lib_crate_generic_function(some_vec);
+    used_only_from_this_lib_crate_generic_function("used ONLY from library used_crate.rs");
+}

tests/coverage-map/if.cov-map

@@ -1,15 +1,15 @@
 Function name: if::main
-Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 03, 01, 02, 0c, 05, 02, 0d, 02, 06, 02, 02, 06, 00, 07, 07, 01, 05, 01, 02]
+Raw bytes (28): 0x[01, 01, 02, 01, 05, 05, 02, 04, 01, 03, 01, 12, 10, 05, 13, 05, 05, 06, 02, 05, 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 + 3, 1) to (start + 2, 12)
-- Code(Counter(1)) at (prev + 2, 13) to (start + 2, 6)
-- Code(Expression(0, Sub)) at (prev + 2, 6) to (start + 0, 7)
+- Code(Counter(0)) at (prev + 3, 1) to (start + 18, 16)
+- Code(Counter(1)) at (prev + 19, 5) to (start + 5, 6)
+- Code(Expression(0, Sub)) at (prev + 5, 6) to (start + 0, 7)
     = (c0 - c1)
-- Code(Expression(1, Add)) at (prev + 1, 5) to (start + 1, 2)
+- Code(Expression(1, Add)) at (prev + 1, 1) to (start + 0, 2)
     = (c1 + (c0 - c1))
 

tests/coverage-map/if.rs

@@ -1,9 +1,28 @@
-// compile-flags: --edition=2021
+#![allow(unused_assignments, unused_variables)]
 
 fn main() {
-    let cond = std::env::args().len() == 1;
-    if cond {
-        println!("true");
+    // Initialize test constants in a way that cannot be determined at compile time, to ensure
+    // rustc and LLVM cannot optimize out statements (or coverage counters) downstream from
+    // dependent conditions.
+    let
+    is_true
+    =
+        std::env::args().len()
+    ==
+        1
+    ;
+    let
+        mut
+    countdown
+    =
+        0
+    ;
+    if
+        is_true
+    {
+        countdown
+        =
+            10
+        ;
     }
-    println!("done");
 }

tests/coverage-map/issue-85461.cov-map

@@ -0,0 +1,8 @@
+Function name: issue_85461::main
+Raw bytes (9): 0x[01, 01, 00, 01, 01, 08, 01, 03, 02]
+Number of files: 1
+- file 0 => global file 1
+Number of expressions: 0
+Number of file 0 mappings: 1
+- Code(Counter(0)) at (prev + 8, 1) to (start + 3, 2)
+

tests/coverage-map/issue-85461.rs

@@ -0,0 +1,11 @@
+// Regression test for #85461: MSVC sometimes fail to link with dead code and #[inline(always)]
+
+// aux-build:inline_always_with_dead_code.rs
+extern crate inline_always_with_dead_code;
+
+use inline_always_with_dead_code::{bar, baz};
+
+fn main() {
+    bar::call_me();
+    baz::call_me();
+}

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

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