[llvm] [hwasan] Add intrinsics for fixed shadow on Aarch64 (PR #89319)

[Vitaly Buka via llvm-commits]

================
@@ -625,14 +635,32 @@ 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.has_value()) {
+      OutStreamer->emitInstruction(
+          MCInstBuilder(AArch64::MOVZXi)
+              .addReg(AArch64::X17)
+              .addImm(HwasanFixedShadowBase.value() >> 32)
+              .addImm(32),
+          *STI);
+      OutStreamer->emitInstruction(MCInstBuilder(AArch64::LDRBBroX)
----------------
vitalybuka wrote:

why there is no difference for short in the fixed shadow version?

https://github.com/llvm/llvm-project/pull/89319