Auto merge of #124676 - djkoloski:relax_multiple_sanitizers, r=cuviper,rcvalle

Relax restrictions on multiple sanitizers

Most combinations of LLVM sanitizers are legal-enough to enable simultaneously. This change will allow simultaneously enabling ASAN and shadow call stacks on supported platforms.

I used this python script to generate the mutually-exclusive sanitizer combinations:

```python
#!/usr/bin/python3

import subprocess

flags = [
    ["-fsanitize=address"],
    ["-fsanitize=leak"],
    ["-fsanitize=memory"],
    ["-fsanitize=thread"],
    ["-fsanitize=hwaddress"],
    ["-fsanitize=cfi", "-flto", "-fvisibility=hidden"],
    ["-fsanitize=memtag", "--target=aarch64-linux-android", "-march=armv8a+memtag"],
    ["-fsanitize=shadow-call-stack"],
    ["-fsanitize=kcfi", "-flto", "-fvisibility=hidden"],
    ["-fsanitize=kernel-address"],
    ["-fsanitize=safe-stack"],
    ["-fsanitize=dataflow"],
]

for i in range(len(flags)):
    for j in range(i):
        command = ["clang++"] + flags[i] + flags[j] + ["-o", "main.o", "-c", "main.cpp"]
        completed = subprocess.run(command, stderr=subprocess.DEVNULL)
        if completed.returncode != 0:
            first = flags[i][0][11:].replace('-', '').upper()
            second = flags[j][0][11:].replace('-', '').upper()
            print(f"(SanitizerSet::{first}, SanitizerSet::{second}),")
```

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1230,7 +1230,10 @@ fn add_sanitizer_libraries(
     if sanitizer.contains(SanitizerSet::DATAFLOW) {
         link_sanitizer_runtime(sess, flavor, linker, "dfsan");
     }
-    if sanitizer.contains(SanitizerSet::LEAK) {
+    if sanitizer.contains(SanitizerSet::LEAK)
+        && !sanitizer.contains(SanitizerSet::ADDRESS)
+        && !sanitizer.contains(SanitizerSet::HWADDRESS)
+    {
         link_sanitizer_runtime(sess, flavor, linker, "lsan");
     }
     if sanitizer.contains(SanitizerSet::MEMORY) {

compiler/rustc_session/src/session.rs

@@ -1183,9 +1183,9 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
             });
         }
     }
-    // Cannot mix and match sanitizers.
-    let mut sanitizer_iter = sess.opts.unstable_opts.sanitizer.into_iter();
-    if let (Some(first), Some(second)) = (sanitizer_iter.next(), sanitizer_iter.next()) {
+
+    // Cannot mix and match mutually-exclusive sanitizers.
+    if let Some((first, second)) = sess.opts.unstable_opts.sanitizer.mutually_exclusive() {
         sess.dcx().emit_err(errors::CannotMixAndMatchSanitizers {
             first: first.to_string(),
             second: second.to_string(),
@@ -1220,14 +1220,6 @@ fn validate_commandline_args_with_session_available(sess: &Session) {
         sess.dcx().emit_err(errors::SanitizerCfiRequiresSingleCodegenUnit);
     }
 
-    // LLVM CFI is incompatible with LLVM KCFI.
-    if sess.is_sanitizer_cfi_enabled() && sess.is_sanitizer_kcfi_enabled() {
-        sess.dcx().emit_err(errors::CannotMixAndMatchSanitizers {
-            first: "cfi".to_string(),
-            second: "kcfi".to_string(),
-        });
-    }
-
     // Canonical jump tables requires CFI.
     if sess.is_sanitizer_cfi_canonical_jump_tables_disabled() {
         if !sess.is_sanitizer_cfi_enabled() {

compiler/rustc_target/src/spec/mod.rs

@@ -1317,6 +1317,34 @@ bitflags::bitflags! {
 rustc_data_structures::external_bitflags_debug! { SanitizerSet }
 
 impl SanitizerSet {
+    // Taken from LLVM's sanitizer compatibility logic:
+    // https://github.com/llvm/llvm-project/blob/release/18.x/clang/lib/Driver/SanitizerArgs.cpp#L512
+    const MUTUALLY_EXCLUSIVE: &'static [(SanitizerSet, SanitizerSet)] = &[
+        (SanitizerSet::ADDRESS, SanitizerSet::MEMORY),
+        (SanitizerSet::ADDRESS, SanitizerSet::THREAD),
+        (SanitizerSet::ADDRESS, SanitizerSet::HWADDRESS),
+        (SanitizerSet::ADDRESS, SanitizerSet::MEMTAG),
+        (SanitizerSet::ADDRESS, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::ADDRESS, SanitizerSet::SAFESTACK),
+        (SanitizerSet::LEAK, SanitizerSet::MEMORY),
+        (SanitizerSet::LEAK, SanitizerSet::THREAD),
+        (SanitizerSet::LEAK, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::LEAK, SanitizerSet::SAFESTACK),
+        (SanitizerSet::MEMORY, SanitizerSet::THREAD),
+        (SanitizerSet::MEMORY, SanitizerSet::HWADDRESS),
+        (SanitizerSet::MEMORY, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::MEMORY, SanitizerSet::SAFESTACK),
+        (SanitizerSet::THREAD, SanitizerSet::HWADDRESS),
+        (SanitizerSet::THREAD, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::THREAD, SanitizerSet::SAFESTACK),
+        (SanitizerSet::HWADDRESS, SanitizerSet::MEMTAG),
+        (SanitizerSet::HWADDRESS, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::HWADDRESS, SanitizerSet::SAFESTACK),
+        (SanitizerSet::CFI, SanitizerSet::KCFI),
+        (SanitizerSet::MEMTAG, SanitizerSet::KERNELADDRESS),
+        (SanitizerSet::KERNELADDRESS, SanitizerSet::SAFESTACK),
+    ];
+
     /// Return sanitizer's name
     ///
     /// Returns none if the flags is a set of sanitizers numbering not exactly one.
@@ -1337,6 +1365,13 @@ impl SanitizerSet {
             _ => return None,
         })
     }
+
+    pub fn mutually_exclusive(self) -> Option<(SanitizerSet, SanitizerSet)> {
+        Self::MUTUALLY_EXCLUSIVE
+            .into_iter()
+            .find(|&(a, b)| self.contains(*a) && self.contains(*b))
+            .copied()
+    }
 }
 
 /// Formats a sanitizer set as a comma separated list of sanitizers' names.

tests/ui/sanitizer/cfi-is-incompatible-with-kcfi.aarch64.stderr

@@ -2,9 +2,5 @@ error: cfi sanitizer is not supported for this target
 
 error: `-Zsanitizer=cfi` is incompatible with `-Zsanitizer=kcfi`
 
-error: `-Zsanitizer=cfi` is incompatible with `-Zsanitizer=kcfi`
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 

tests/ui/sanitizer/cfi-is-incompatible-with-kcfi.x86_64.stderr

@@ -2,9 +2,5 @@ error: cfi sanitizer is not supported for this target
 
 error: `-Zsanitizer=cfi` is incompatible with `-Zsanitizer=kcfi`
 
-error: `-Zsanitizer=cfi` is incompatible with `-Zsanitizer=kcfi`
-   |
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors