[llvm] [llvm] Implement address sanitizer on AIX (2/3) (PR #129926)

[Jake Egan via llvm-commits]

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@@ -1326,7 +1340,11 @@ static bool isUnsupportedAMDGPUAddrspace(Value *Addr) {
 
 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
   // Shadow >> scale
-  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
+  if (TargetTriple.isOSAIX() && TargetTriple.getArch() == Triple::ppc64)
+    Shadow = IRB.CreateLShr(IRB.CreateShl(Shadow, Mapping.HighBits),
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jakeegan wrote:

Unfortunately I think we have to diverge from the default implementation because the address ranges on 64-bit AIX are large, resulting in a large shadow region, so we use HIGH_BITS to limit it. More details on the mapping:
https://github.com/llvm/llvm-project/blob/e9e590e350df5877d717bb667f20bbc60a9de0ee/compiler-rt/lib/asan/asan_mapping_aix64.h

0x90100000f000000 is mapped to 0x20200001e00000 while 0x100000f000000 is mapped to 0x200001e00000



https://github.com/llvm/llvm-project/pull/129926