[clang] [CIR][RISCV] Support zihintpause builitin codegen (PR #188465)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clangir

@llvm/pr-subscribers-clang

Author: Jianjian Guan (jacquesguan)

<details>
<summary>Changes</summary>

Include one builtin: __builtin_riscv_pause.

---
Full diff: https://github.com/llvm/llvm-project/pull/188465.diff


2 Files Affected:

- (modified) clang/lib/CIR/CodeGen/CIRGenBuiltinRISCV.cpp (+30-2) 
- (added) clang/test/CIR/CodeGenBuiltins/RISCV/riscv-zihintpause.c (+22) 


``````````diff
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuiltinRISCV.cpp b/clang/lib/CIR/CodeGen/CIRGenBuiltinRISCV.cpp
index 899ba253be7c9..98c2d492b01f9 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltinRISCV.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltinRISCV.cpp
@@ -27,6 +27,20 @@ CIRGenFunction::emitRISCVBuiltinExpr(unsigned builtinID, const CallExpr *e) {
                      getContext().BuiltinInfo.getName(builtinID));
     return mlir::Value{};
   }
+
+  StringRef intrinsicName;
+  mlir::Type intrinisicType;
+  llvm::SmallVector<mlir::Value> ops;
+
+  // `ICEArguments` is a bitmap indicating whether the argument at the i-th bit
+  // is required to be a constant integer expression.
+  unsigned iceArguments = 0;
+  ASTContext::GetBuiltinTypeError error;
+  getContext().GetBuiltinType(builtinID, error, &iceArguments);
+  assert(error == ASTContext::GE_None && "Should not codegen an error");
+  for (auto [idx, arg] : llvm::enumerate(e->arguments()))
+    ops.push_back(emitScalarOrConstFoldImmArg(iceArguments, idx, arg));
+
   switch (builtinID) {
   default:
     llvm_unreachable("unexpected builtin ID");
@@ -69,9 +83,20 @@ CIRGenFunction::emitRISCVBuiltinExpr(unsigned builtinID, const CallExpr *e) {
   case RISCV::BI__builtin_riscv_ctz_64:
   // Zihintntl
   case RISCV::BI__builtin_riscv_ntl_load:
-  case RISCV::BI__builtin_riscv_ntl_store:
+  case RISCV::BI__builtin_riscv_ntl_store: {
+    cgm.errorNYI(e->getSourceRange(),
+                 std::string("unimplemented RISC-V builtin call: ") +
+                     getContext().BuiltinInfo.getName(builtinID));
+    return mlir::Value{};
+  }
+
   // Zihintpause
-  case RISCV::BI__builtin_riscv_pause:
+  case RISCV::BI__builtin_riscv_pause: {
+    intrinsicName = "riscv.pause";
+    intrinisicType = builder.getVoidTy();
+    break;
+  }
+
   // XCValu
   case RISCV::BI__builtin_riscv_cv_alu_addN:
   case RISCV::BI__builtin_riscv_cv_alu_addRN:
@@ -109,4 +134,7 @@ CIRGenFunction::emitRISCVBuiltinExpr(unsigned builtinID, const CallExpr *e) {
 
     // TODO: Handle vector builtins in tablegen.
   }
+
+  mlir::Location loc = getLoc(e->getSourceRange());
+  return builder.emitIntrinsicCallOp(loc, intrinsicName, intrinisicType, ops);
 }
diff --git a/clang/test/CIR/CodeGenBuiltins/RISCV/riscv-zihintpause.c b/clang/test/CIR/CodeGenBuiltins/RISCV/riscv-zihintpause.c
new file mode 100644
index 0000000000000..b9bbaec468c8b
--- /dev/null
+++ b/clang/test/CIR/CodeGenBuiltins/RISCV/riscv-zihintpause.c
@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -triple riscv32 -target-feature +zihintpause -fclangir -emit-cir %s -o - | FileCheck %s --check-prefix=CIR
+// RUN: %clang_cc1 -triple riscv64 -target-feature +zihintpause -fclangir -emit-cir %s -o - | FileCheck %s --check-prefix=CIR
+// RUN: %clang_cc1 -triple riscv32 -target-feature +zihintpause -fclangir -emit-llvm %s -o - | FileCheck %s --check-prefix=LLVM
+// RUN: %clang_cc1 -triple riscv64 -target-feature +zihintpause -fclangir -emit-llvm %s -o - | FileCheck %s --check-prefix=LLVM
+// RUN: %clang_cc1 -triple riscv32 -target-feature +zihintpause -emit-llvm %s -o - | FileCheck %s --check-prefix=OGCG
+// RUN: %clang_cc1 -triple riscv64 -target-feature +zihintpause -emit-llvm %s -o - | FileCheck %s --check-prefix=OGCG
+
+void test_builtin_pause(void) {
+  __builtin_riscv_pause();
+}
+
+// CIR-LABEL: cir.func{{.*}} @test_builtin_pause(
+// CIR: {{%.*}} = cir.call_llvm_intrinsic "riscv.pause" : () -> !void
+// CIR: cir.return
+
+// LLVM-LABEL: define dso_local void @test_builtin_pause(
+// LLVM: call void @llvm.riscv.pause()
+// LLVM: ret void
+
+// OGCG-LABEL: define dso_local void @test_builtin_pause(
+// OGCG: call void @llvm.riscv.pause()
+// OGCG: ret void

``````````

</details>


https://github.com/llvm/llvm-project/pull/188465