diff options
authorStephan Bergmann <>2020-01-07 17:35:18 +0100
committerStephan Bergmann <>2020-01-07 20:27:57 +0100
commit386248c9c2de669c211ba5a06afc8466f14c542b (patch)
parent8cd00ec92f291dd01e0eed27fc144785bed5e44e (diff)
aarch64 r18 is reserved at least on Android
< aapcs64.rst> states: "The role of register r18 is platform specific. If a platform ABI has need of a dedicated general purpose register to carry inter- procedural state (for example, the thread context) then it should use this register for that purpose. If the platform ABI has no such requirements, then it should use r18 as an additional temporary register." For a --host=aarch64-linux-android build, Clang warned > bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx:39:9: error: inline asm clobber list contains reserved registers: X18 [-Werror,-Winline-asm] > "ldp x0, x1, [%[gpr_]]\n\t" > ^ > <inline asm>:1:1: note: instantiated into assembly here > ldp x0, x1, [x20] > ^ > bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx:39:9: note: Reserved registers on the clobber list may not be preserved across the asm statement, and clobbering them may lead to undefined behaviour. > "ldp x0, x1, [%[gpr_]]\n\t" > ^ > <inline asm>:1:1: note: instantiated into assembly here > ldp x0, x1, [x20] > ^ and < 9c9c8b22d2ea150cc889232871b0c8303d3644d9> "Start reserving x18 by default on Android targets" shows that at least LLVM/Clang claims that the Android ABI reserves it (though it doesn't cite any sources for that). (If this bridges/source/cpp_uno/ implementation is used for other non-Linux OS like Fuchsia, we may need to extend the #if accordingly; see the above LLVM commit for which platforms it claims reserve the register.) Change-Id: I62a5210ddc4784eee2ab56ee134b9e195827b9dd Reviewed-on: Tested-by: Jenkins Reviewed-by: Stephan Bergmann <>
1 files changed, 5 insertions, 2 deletions
diff --git a/bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx b/bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx
index 2f7188ea4f99..ba5194d6f8c8 100644
--- a/bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx
+++ b/bridges/source/cpp_uno/gcc3_linux_aarch64/callvirtualfunction.cxx
@@ -54,8 +54,11 @@ void callVirtualFunction(
[ret_]"m" (ret),
"m" (stackargs) // dummy input to prevent optimizing the alloca away
: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10",
- "r11", "r12", "r13", "r14", "r15", "r16", "r17", "r18"/*TODO?*/, "v0",
- "v1", "v2", "v3", "v4", "v5", "v6", "v7", "v8", "v9", "v10", "v11",
+ "r11", "r12", "r13", "r14", "r15", "r16", "r17",
+#if !defined ANDROID
+ "r18"/*TODO?*/,
+ "v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7", "v8", "v9", "v10", "v11",
"v12", "v13", "v14", "v15", "v16", "v17", "v18", "v19", "v20", "v21",
"v22", "v23", "v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31",