[clang] e090c86 - [clang] deduplicate target-features for modules (#187614)

[via cfe-commits]

Author: Florian Mayer
Date: 2026-04-08T10:29:33-07:00
New Revision: e090c86ab0c7d6775882e124a8bab922c46d5ab3

URL: https://github.com/llvm/llvm-project/commit/e090c86ab0c7d6775882e124a8bab922c46d5ab3
DIFF: https://github.com/llvm/llvm-project/commit/e090c86ab0c7d6775882e124a8bab922c46d5ab3.diff

LOG: [clang] deduplicate target-features for modules (#187614)

Previously, double passing a target feature would make the module
incompatible with a compilation unit that only passes it once.

The motivating problem is, when we pass -target-features +tagged-globals
as well as -fsanitize=hwaddress, which adds a second copy, the module
is incompatible with one built with only one `-target-features
+tagged-globals`.

Added: 
    

Modified: 
    clang/lib/Serialization/ASTReader.cpp
    clang/test/Modules/merge-target-features.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 2ad6de58f56e1..b328114ef240f 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -497,7 +497,10 @@ static bool checkTargetOptions(const TargetOptions &TargetOpts,
   SmallVector<StringRef, 4> ReadFeatures(TargetOpts.FeaturesAsWritten.begin(),
                                          TargetOpts.FeaturesAsWritten.end());
   llvm::sort(ExistingFeatures);
+  ExistingFeatures.erase(llvm::unique(ExistingFeatures),
+                         ExistingFeatures.end());
   llvm::sort(ReadFeatures);
+  ReadFeatures.erase(llvm::unique(ReadFeatures), ReadFeatures.end());
 
   // We compute the set 
diff erence in both directions explicitly so that we can
   // diagnose the 
diff erences 
diff erently.

diff  --git a/clang/test/Modules/merge-target-features.cpp b/clang/test/Modules/merge-target-features.cpp
index 73474e1388fb6..01d38a1eb0d13 100644
--- a/clang/test/Modules/merge-target-features.cpp
+++ b/clang/test/Modules/merge-target-features.cpp
@@ -10,6 +10,15 @@
 // RUN:   -target-cpu i386 -target-feature +sse2 \
 // RUN:   Inputs/merge-target-features/module.modulemap
 //
+// RUN: %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \
+// RUN:   -iquote Inputs/merge-target-features \
+// RUN:   -fno-implicit-modules \
+// RUN:   -fmodule-map-file-home-is-cwd \
+// RUN:   -emit-module -fmodule-name=foo -o %t/foo-double.pcm \
+// RUN:   -triple i386-unknown-unknown \
+// RUN:   -target-cpu i386 -target-feature +sse2 -target-feature +sse2 \
+// RUN:   Inputs/merge-target-features/module.modulemap
+//
 // RUN: not %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \
 // RUN:   -iquote Inputs/merge-target-features \
 // RUN:   -fno-implicit-modules \
@@ -60,6 +69,18 @@
 // MISMATCH: error: precompiled file '{{.*}}foo.pcm' was compiled with the target feature '+sse2' but the current translation unit is not
 // MISMATCH: error: current translation unit is compiled with the target feature '+cx16' but the precompiled file '{{.*}}foo.pcm' was not
 // MISMATCH: error: {{.*}} configuration mismatch
+//
+// RUN: %clang_cc1 -fmodules -x c++ -fmodules-cache-path=%t \
+// RUN:   -iquote Inputs/merge-target-features \
+// RUN:   -fno-implicit-modules \
+// RUN:   -fmodule-map-file-home-is-cwd \
+// RUN:   -fmodule-map-file=Inputs/merge-target-features/module.modulemap \
+// RUN:   -fmodule-file=%t/foo-double.pcm \
+// RUN:   -triple i386-unknown-unknown \
+// RUN:   -target-cpu i386 -target-feature +sse2 \
+// RUN:   -fsyntax-only merge-target-features.cpp 2>&1 \
+// RUN:   | FileCheck --allow-empty --check-prefix=DOUBLE %s
+// DOUBLE-NOT: error:
 
 #include "foo.h"