[clang] [llvm] [BPF] introduce `__attribute__((bpf_fastcall))` (PR #101228)

[via cfe-commits]

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@@ -0,0 +1,24 @@
+// REQUIRES: bpf-registered-target
+// RUN: %clang_cc1 -triple bpf -emit-llvm -disable-llvm-passes %s -o - | FileCheck %s
+
+#define __bpf_fastcall __attribute__((bpf_fastcall))
+
+void test(void) __bpf_fastcall;
+void (*ptr)(void) __bpf_fastcall;
+
+void foo(void) {
+  test();
+  (*ptr)();
+}
+
+// CHECK: @ptr = global ptr null
+// CHECK: define {{.*}} @foo()
+// CHECK: entry:
+// CHECK:   call void @test() #[[test_attr:[0-9]+]]
+// CHECK:   %[[ptr:.*]] = load ptr, ptr @ptr, align 8
+// CHECK:   call void %[[ptr]]() #[[test_attr]]
+// CHECK:   ret void
+
+// CHECK: declare void @test() #[[ptr_attr:[0-9]+]]
+// CHECK: attributes #1 = { {{.*}}"bpf_fastcall"{{.*}} }
+// CHECK: attributes #[[test_attr]] = { {{.*}}"bpf_fastcall"{{.*}} }
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eddyz87 wrote:

only for `#1`, I'll remove `{{.*}}` for `test_attr`.

https://github.com/llvm/llvm-project/pull/101228