[clang] 8a1d6c6 - clang: driver: update android packed relocation logic (#189758)

[via cfe-commits]

Author: Nick Desaulniers
Date: 2026-04-01T16:04:34Z
New Revision: 8a1d6c6f5e421bcade951ce9df4d9d300075cab7

URL: https://github.com/llvm/llvm-project/commit/8a1d6c6f5e421bcade951ce9df4d9d300075cab7
DIFF: https://github.com/llvm/llvm-project/commit/8a1d6c6f5e421bcade951ce9df4d9d300075cab7.diff

LOG: clang: driver: update android packed relocation logic (#189758)

Hoist this up from the build system so that users of Android's NDK can
benefit from these various packed relocation encodings depending on
which API level they are targeting.

Link: https://github.com/android/ndk/issues/909
Fixes: https://github.com/android/ndk/issues/2193
Link: https://github.com/android/ndk/issues/2188#issuecomment-3366591142
Link:
https://android.googlesource.com/platform/build/soong/+/d046c2afef086a35d24222b09f4d2c4914e8a2a5/cc/linker.go#548

Added: 
    

Modified: 
    clang/lib/Driver/ToolChains/Linux.cpp
    clang/test/Driver/linux-ld.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Linux.cpp b/clang/lib/Driver/ToolChains/Linux.cpp
index 62746e9048cee..cf67f984ccdd2 100644
--- a/clang/lib/Driver/ToolChains/Linux.cpp
+++ b/clang/lib/Driver/ToolChains/Linux.cpp
@@ -274,15 +274,16 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
       // issue that this flag is not accepted by other linkers.
       ExtraOpts.push_back("--no-rosegment");
     }
-    if (!Triple.isAndroidVersionLT(28)) {
-      // Android supports relr packing starting with API 28 and had its own
-      // flavor (--pack-dyn-relocs=android) starting in API 23.
-      // TODO: It's possible to use both with --pack-dyn-relocs=android+relr,
-      // but we need to gather some data on the impact of that form before we
-      // can know if it's a good default.
-      // On the other hand, relr should always be an improvement.
+    // SHT_RELR relocations are only supported at API level >= 30.
+    // ANDROID_RELR relocations were supported at API level >= 28.
+    // Relocation packer was supported at API level >= 23.
+    if (!Triple.isAndroidVersionLT(30)) {
+      ExtraOpts.push_back("--pack-dyn-relocs=android+relr");
+    } else if (!Triple.isAndroidVersionLT(28)) {
+      ExtraOpts.push_back("--pack-dyn-relocs=android+relr");
       ExtraOpts.push_back("--use-android-relr-tags");
-      ExtraOpts.push_back("--pack-dyn-relocs=relr");
+    } else if (!Triple.isAndroidVersionLT(23)) {
+      ExtraOpts.push_back("--pack-dyn-relocs=android");
     }
   }
 

diff  --git a/clang/test/Driver/linux-ld.c b/clang/test/Driver/linux-ld.c
index be3293cdc253e..2c9d3a6ec3f90 100644
--- a/clang/test/Driver/linux-ld.c
+++ b/clang/test/Driver/linux-ld.c
@@ -954,21 +954,53 @@
 // CHECK-ANDROID-ROSEGMENT-29: "{{.*}}ld{{(.exe)?}}"
 // CHECK-ANDROID-ROSEGMENT-29-NOT: "--no-rosegment"
 
-// Check that we pass --pack-dyn-relocs=relr for API 28+ and not before.
+// Check that we pass --pack-dyn-relocs=android for API 23-27 and not before.
+// RUN: %clang %s -### -o %t.o 2>&1 \
+// RUN:     --target=armv7-linux-android22 \
+// RUN:   | FileCheck --check-prefix=CHECK-ANDROID-RELR-22 %s
+// CHECK-ANDROID-RELR-22: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-RELR-22-NOT: "--pack-dyn-relocs=android"
+// CHECK-ANDROID-RELR-22-NOT: "--pack-dyn-relocs=relr"
+// CHECK-ANDROID-RELR-22-NOT: "--pack-dyn-relocs=android+relr"
+// CHECK-ANDROID-RELR-22-NOT: "--use-android-relr-tags"
+//
+// RUN: %clang %s -### -o %t.o 2>&1 \
+// RUN:     --target=armv7-linux-android23 \
+// RUN:   | FileCheck --check-prefix=CHECK-ANDROID-RELR-23 %s
+// CHECK-ANDROID-RELR-23: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-RELR-23: "--pack-dyn-relocs=android"
+// CHECK-ANDROID-RELR-23-NOT: "--pack-dyn-relocs=relr"
+// CHECK-ANDROID-RELR-23-NOT: "--pack-dyn-relocs=android+relr"
+// CHECK-ANDROID-RELR-23-NOT: "--use-android-relr-tags"
+//
+// Check that we pass --pack-dyn-relocs=relr --use-android-relr-tags for API 28-30 and not before.
 // RUN: %clang %s -### -o %t.o 2>&1 \
 // RUN:     --target=armv7-linux-android27 \
 // RUN:   | FileCheck --check-prefix=CHECK-ANDROID-RELR-27 %s
 // CHECK-ANDROID-RELR-27: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-RELR-27: "--pack-dyn-relocs=android"
 // CHECK-ANDROID-RELR-27-NOT: "--pack-dyn-relocs=relr"
 // CHECK-ANDROID-RELR-27-NOT: "--pack-dyn-relocs=android+relr"
+// CHECK-ANDROID-RELR-27-NOT: "--use-android-relr-tags"
 //
 // RUN: %clang %s -### -o %t.o 2>&1 \
 // RUN:     --target=armv7-linux-android28 \
 // RUN:   | FileCheck --check-prefix=CHECK-ANDROID-RELR-28 %s
 // CHECK-ANDROID-RELR-28: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-RELR-28: "--pack-dyn-relocs=android+relr"
 // CHECK-ANDROID-RELR-28: "--use-android-relr-tags"
-// CHECK-ANDROID-RELR-28: "--pack-dyn-relocs=relr"
-// CHECK-ANDROID-RELR-28-NOT: "--pack-dyn-relocs=android+relr"
+// CHECK-ANDROID-RELR-28-NOT: "--pack-dyn-relocs=android"
+// CHECK-ANDROID-RELR-28-NOT: "--pack-dyn-relocs=relr"
+//
+// Check that we stop passing --use-android-relr-tags for ABI 30+.
+// RUN: %clang %s -### -o %t.o 2>&1 \
+// RUN:     --target=armv7-linux-android30 \
+// RUN:   | FileCheck --check-prefix=CHECK-ANDROID-RELR-30 %s
+// CHECK-ANDROID-RELR-30: "{{.*}}ld{{(.exe)?}}"
+// CHECK-ANDROID-RELR-30: "--pack-dyn-relocs=android+relr"
+// CHECK-ANDROID-RELR-30-NOT: "--use-android-relr-tags"
+// CHECK-ANDROID-RELR-30-NOT: "--pack-dyn-relocs=android"
+// CHECK-ANDROID-RELR-30-NOT: "--pack-dyn-relocs=relr"
 
 // RUN: %clang -### %s -no-pie 2>&1 --target=mips64-linux-gnuabin32 \
 // RUN:   | FileCheck --check-prefix=CHECK-MIPS64EL-GNUABIN32 %s