[llvm] [hwasan] Optimize outlined memaccess for fixed shadow on Aarch64 (PR #88544)

[Vitaly Buka via llvm-commits]

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@@ -930,11 +930,32 @@ void HWAddressSanitizer::instrumentMemAccessOutline(Value *Ptr, bool IsWrite,
 
   IRBuilder<> IRB(InsertBefore);
   Module *M = IRB.GetInsertBlock()->getParent()->getParent();
-  IRB.CreateCall(Intrinsic::getDeclaration(
-                     M, UseShortGranules
-                            ? Intrinsic::hwasan_check_memaccess_shortgranules
-                            : Intrinsic::hwasan_check_memaccess),
-                 {ShadowBase, Ptr, ConstantInt::get(Int32Ty, AccessInfo)});
+  bool useFixedShadowIntrinsic = false;
+  // The memaccess fixed shadow intrinsic is only supported on AArch64,
+  // which allows a 16-bit immediate to be left-shifted by 32.
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vitalybuka wrote:

what is `16-bit immediate` ?

https://github.com/llvm/llvm-project/pull/88544