[llvm] [AArch64] support `.arch_extension dit` (PR #169999)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Folkert de Vries (folkertdev)

<details>
<summary>Changes</summary>

fixes https://github.com/llvm/llvm-project/issues/146866

The issue discusses that it is unfortunate that command line flag parsing and assembly parsing don't share the infrastructure for recognizing features, which can lead to inconsistencies like here. I don't really see how I can combine them though, so for now this change will fix the immediate problem.

---
Full diff: https://github.com/llvm/llvm-project/pull/169999.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp (+1) 
- (modified) llvm/test/MC/AArch64/directive-arch_extension.s (+4) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
index 433cb0387c470..7116fd0ea3b6f 100644
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -3954,6 +3954,7 @@ static const struct Extension {
     {"poe2", {AArch64::FeatureS1POE2}},
     {"tev", {AArch64::FeatureTEV}},
     {"btie", {AArch64::FeatureBTIE}},
+    {"dit", {AArch64::FeatureDIT}},
 };
 
 static void setRequiredFeatureString(FeatureBitset FBS, std::string &Str) {
diff --git a/llvm/test/MC/AArch64/directive-arch_extension.s b/llvm/test/MC/AArch64/directive-arch_extension.s
index 3c754077572a1..f174e9d4d187e 100644
--- a/llvm/test/MC/AArch64/directive-arch_extension.s
+++ b/llvm/test/MC/AArch64/directive-arch_extension.s
@@ -197,3 +197,7 @@ fmmla v1.8h, v2.16b, v3.16b
 .arch_extension f8f32mm
 fmmla v1.4s, v2.16b, v3.16b
 // CHECK: fmmla v1.4s, v2.16b, v3.16b
+
+.arch_extension dit
+msr DIT, #1
+// CHECK: msr DIT, #1

``````````

</details>


https://github.com/llvm/llvm-project/pull/169999