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

[Sean Fertile 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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mandlebug wrote:

A large part of the address space is reserved by the OS and not available to the compiler/runtime. The mapping scheme Jake is using is because we have to map the shadow memory into the mmap range from `0x0a00 0000 0000 0000` to `0x0aff ffff ffff ffff`. 

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