[clang] [clang] Unify -mspeculative-load-hardening as a benign compiler option (PR #166640)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Cyndy Ishida (cyndyishida)

<details>
<summary>Changes</summary>

Before this patch, compilations using modules &
`-mspeculative-load-hardening` failed because it was not consistent whether this option impacts module compatibility.

This repairs it by always treating it as benign. This was determined by checking if the option enables any kind of preprocessor checks and comparing how the compiler handles a similar option that impacts codegen (-fvisibility=hidden) but is more widely used.

resolves: rdar://163985667

---
Full diff: https://github.com/llvm/llvm-project/pull/166640.diff


2 Files Affected:

- (modified) clang/include/clang/Basic/LangOptions.def (+1-1) 
- (modified) clang/test/ClangScanDeps/strip-codegen-args.m (+6) 


``````````diff
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index d3cca82b4bdff..40fc66ea12e34 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -454,7 +454,7 @@ LANGOPT(BranchTargetEnforcement, 1, 0, NotCompatible, "Branch-target enforcement
 LANGOPT(BranchProtectionPAuthLR, 1, 0, NotCompatible, "Use PC as a diversifier using PAuthLR NOP instructions.")
 LANGOPT(GuardedControlStack, 1, 0, NotCompatible, "Guarded control stack enabled")
 
-LANGOPT(SpeculativeLoadHardening, 1, 0, NotCompatible, "Speculative load hardening enabled")
+LANGOPT(SpeculativeLoadHardening, 1, 0, Benign, "Speculative load hardening enabled")
 
 LANGOPT(RelativeCXXABIVTables, 1, 0, NotCompatible,
         "Use an ABI-incompatible v-table layout that uses relative references")
diff --git a/clang/test/ClangScanDeps/strip-codegen-args.m b/clang/test/ClangScanDeps/strip-codegen-args.m
index 71171f4983386..f2cec6281f7df 100644
--- a/clang/test/ClangScanDeps/strip-codegen-args.m
+++ b/clang/test/ClangScanDeps/strip-codegen-args.m
@@ -16,6 +16,7 @@
 // CHECK-NOT:          "-flto"
 // CHECK-NOT:          "-fno-autolink"
 // CHECK-NOT:          "-mrelax-relocations=no"
+// CHECK-NOT:          "-mspeculative-load-hardening"
 // CHECK:            ]
 // CHECK:            "name": "A"
 // CHECK:          }
@@ -39,6 +40,11 @@
     "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -O2 -flto=full -fsyntax-only DIR/t3.m",
     "file": "DIR/t2.m"
   }
+  {
+    "directory": "DIR",
+    "command": "clang -Imodules/A -fmodules -fmodules-cache-path=DIR/module-cache -fimplicit-modules -O2 -mspeculative-load-hardening -fsyntax-only DIR/t3.m",
+    "file": "DIR/t3.m"
+  }
 ]
 
 //--- modules/A/module.modulemap

``````````

</details>


https://github.com/llvm/llvm-project/pull/166640