[clang] [llvm] [CodeGen][AArch64][FMV] PAC the stub_helper's frame on arm64e (PR #84704)

[Pavel Iliin via llvm-commits]

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@@ -0,0 +1,58 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --function-signature --check-attributes --check-globals --include-generated-funcs
+// RUN: %clang_cc1 -triple arm64e-apple-ios -target-feature +ls64 -target-feature +fullfp16 -S -emit-llvm -o - %s | FileCheck %s
+
+int __attribute__((target_version("sha1"))) fmv(void) { return 1; }
+int __attribute__((target_version("default"))) fmv(void) { return 0; }
+int foo() {
+  return fmv();
+}
+
+//.
+// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
+// CHECK: @fmv.ifunc = weak_odr alias i32 (), ptr @fmv
+// CHECK: @fmv = weak_odr ifunc i32 (), ptr @fmv.resolver
+//.
+// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK-LABEL: define {{[^@]+}}@fmv._Msha1
+// CHECK-SAME: () #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    ret i32 1
+//
+//
+// CHECK: Function Attrs: noinline nounwind optnone
+// CHECK-LABEL: define {{[^@]+}}@foo
+// CHECK-SAME: () #[[ATTR1:[0-9]+]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[CALL:%.*]] = call i32 @fmv()
+// CHECK-NEXT:    ret i32 [[CALL]]
+//
+//
+// CHECK-LABEL: define {{[^@]+}}@fmv.resolver
+// CHECK-SAME: () #[[ATTR2:[0-9]+]] {
+// CHECK-NEXT:  resolver_entry:
+// CHECK-NEXT:    call void @__init_cpu_features_resolver()
+// CHECK-NEXT:    [[TMP0:%.*]] = load i64, ptr @__aarch64_cpu_features, align 8
+// CHECK-NEXT:    [[TMP1:%.*]] = and i64 [[TMP0]], 2048
+// CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i64 [[TMP1]], 2048
+// CHECK-NEXT:    [[TMP3:%.*]] = and i1 true, [[TMP2]]
+// CHECK-NEXT:    br i1 [[TMP3]], label [[RESOLVER_RETURN:%.*]], label [[RESOLVER_ELSE:%.*]]
+// CHECK:       resolver_return:
+// CHECK-NEXT:    ret ptr @fmv._Msha1
+// CHECK:       resolver_else:
+// CHECK-NEXT:    ret ptr @fmv.default
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ilinpv wrote:

Looks useful for arm64 as well, could you reveal more details on the machinery and approach to PAC resolver?

https://github.com/llvm/llvm-project/pull/84704