[llvm][docs] MemTagSanitizer is only supported on AArch64 Android #120545
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``` $ ./bin/clang /tmp/test.c -o /tmp/test.o -target aarch64-linux -march=armv8+memtag -fsanitize=memtag-stack clang: error: unsupported option '-fsanitize=memtag*' for target 'aarch64-unknown-linux' ``` But this works: ``` $ ./bin/clang /tmp/test.c -o /tmp/test.o -target aarch64-linux-android -march=armv8+memtag -fsanitize=memtag-stack ``` Due to this check in Clang: https://github.com/llvm/llvm-project/blob/2210da3b823ccf21fc634c858827c9f12c864b51/clang/lib/Driver/ToolChains/CommonArgs.cpp#L1651 Likely because the required notes and dynamic loader support only exist for Android. You can get around this, sort of, by not linking the file. However this means you have to provide your own way of loading it, so it doesn't change the statement that this feature is Android only.
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@llvm/pr-subscribers-compiler-rt-sanitizer Author: David Spickett (DavidSpickett) ChangesBut this works: Due to this check in Clang: Likely because the required notes and dynamic loader support only exist for Android. You can get around this, sort of, by not linking the file. However this means you have to provide your own way of loading it, so it doesn't change the statement that this feature is Android only. #64692 also confirms that the intent is to only support Android at this time. Full diff: https://github.com/llvm/llvm-project/pull/120545.diff 1 Files Affected:
diff --git a/llvm/docs/MemTagSanitizer.rst b/llvm/docs/MemTagSanitizer.rst
index 62efbfb041cbd0..44d261bec028f9 100644
--- a/llvm/docs/MemTagSanitizer.rst
+++ b/llvm/docs/MemTagSanitizer.rst
@@ -29,9 +29,9 @@ Usage
=====
Compile and link your program with ``-fsanitize=memtag`` flag. This
-will only work when targeting AArch64 with MemTag extension. One
+will only work when targeting AArch64 Android with MemTag extension. One
possible way to achieve that is to add ``-target
-aarch64-linux -march=armv8+memtag`` to compilation flags.
+aarch64-linux-android -march=armv8+memtag`` to compilation flags.
Implementation
==============
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fmayer
reviewed
Dec 19, 2024
vitalybuka
approved these changes
Dec 20, 2024
MaskRay
approved these changes
Dec 20, 2024
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But this works:
Due to this check in Clang:
llvm-project/clang/lib/Driver/ToolChains/CommonArgs.cpp
Line 1651 in 2210da3
Likely because the required notes and dynamic loader support only exist for Android.
You can get around this, sort of, by not linking the file. However this means you have to provide your own way of loading it, so it doesn't change the statement that this feature is Android only.
#64692 also confirms that the intent is to only support Android at this time.
And while I'm here, suggest an additive set of flags that can also be used.