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

[Vitaly Buka via llvm-commits]

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@@ -625,14 +638,32 @@ void AArch64AsmPrinter::emitHwasanMemaccessSymbols(Module &M) {
                                      .addImm(4)
                                      .addImm(55),
                                  *STI);
-    OutStreamer->emitInstruction(
-        MCInstBuilder(AArch64::LDRBBroX)
-            .addReg(AArch64::W16)
-            .addReg(IsShort ? AArch64::X20 : AArch64::X9)
-            .addReg(AArch64::X16)
-            .addImm(0)
-            .addImm(0),
-        *STI);
+
+    if (HwasanFixedShadowBase != (unsigned long long)-1) {
+      assert(IsShort);
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vitalybuka wrote:

We should support, instead of explaining.

And we may want non-shorts for SelHWASAN

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