[clang] [CIR] Support x86 builtin rdtsc (PR #180714)

[Priyanshu Kumar via cfe-commits]

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@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -x c -ffreestanding -triple x86_64-unknown-linux -fclangir -emit-cir -o %t.cir %s
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+
+// RUN: %clang_cc1 -x c -ffreestanding -triple x86_64-unknown-linux -fclangir -emit-llvm -o %t.ll %s
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
+
+unsigned long long test_rdtsc() {
+  // CIR-LABEL: @test_rdtsc
+  // CIR: {{%.*}} = cir.call_llvm_intrinsic "x86.rdtsc"() : () -> !u64i
+
+  // LLVM-LABEL: @test_rdtsc
+  // LLVM: call i64 @llvm.x86.rdtsc()
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Priyanshu3820 wrote:

We also test them against the LLVM IR produced by classic codegen to verify the LLVM IR produced by the CIR path. You can use adjacent test files as a reference for that. Also, we try to keep the names of the test files the same as classic codegen. So, you need to change the name of this file to `rd-builtins.c`.

https://github.com/llvm/llvm-project/pull/180714