From 2a3a1c2dc98670c6a5dd24f8b56df17c6ccd96c3 Mon Sep 17 00:00:00 2001
From: Andi Drebes <andi@drebesium.org>
Date: Wed, 31 Jul 2024 15:57:57 +0200
Subject: [PATCH] Implement builtin functions __builtin_ctz{s,,l,ll}

Implement the builtin functions `__builtin_ctzs`, `__builtin_ctz`,
`__builtin_ctzl`, and `__builtin_ctzll` by mapping them to
`math.cttz`.
---
 tools/cgeist/Lib/CGCall.cc           | 11 ++++++++
 tools/cgeist/Test/Verification/ctz.c | 40 ++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 tools/cgeist/Test/Verification/ctz.c

diff --git a/tools/cgeist/Lib/CGCall.cc b/tools/cgeist/Lib/CGCall.cc
index 51a9a1939fab..9d8fa006d2cb 100644
--- a/tools/cgeist/Lib/CGCall.cc
+++ b/tools/cgeist/Lib/CGCall.cc
@@ -567,6 +567,17 @@ MLIRScanner::EmitClangBuiltinCallExpr(clang::CallExpr *expr) {
     return success(
         ValueCategory(castInteger(builder, loc, res, postTy), /*isRef*/ false));
   }
+  case Builtin::BI__builtin_ctzs:
+  case Builtin::BI__builtin_ctz:
+  case Builtin::BI__builtin_ctzl:
+  case Builtin::BI__builtin_ctzll: {
+    auto v = Visit(expr->getArg(0));
+    assert(!v.isReference);
+    Value res = builder.create<math::CountTrailingZerosOp>(loc, v.val);
+    auto postTy = getMLIRType(expr->getType()).cast<mlir::IntegerType>();
+    return success(
+        ValueCategory(castInteger(builder, loc, res, postTy), /*isRef*/ false));
+  }
   default:
     break;
   }
diff --git a/tools/cgeist/Test/Verification/ctz.c b/tools/cgeist/Test/Verification/ctz.c
new file mode 100644
index 000000000000..d288f829557b
--- /dev/null
+++ b/tools/cgeist/Test/Verification/ctz.c
@@ -0,0 +1,40 @@
+// RUN: cgeist %s %stdinclude --function=* -S | FileCheck %s
+
+// CHECK:      func.func @do_ctzs(%[[ARG:[A-Za-z0-9_]*]]: i16) -> i32
+// CHECK-NEXT:   %[[VAL_0:[A-Za-z0-9_]*]] = math.cttz %[[ARG]] : i16
+// CHECK-NEXT:   %[[VAL_1:[A-Za-z0-9_]*]] = arith.extui %[[VAL_0]] : i16 to i32
+// CHECK-NEXT:   return %[[VAL_1]] : i32
+// CHECK-NEXT: }
+
+int do_ctzs(short int i) {
+  return __builtin_ctzs(i);
+}
+
+// CHECK:      func.func @do_ctz(%[[ARG:[A-Za-z0-9_]*]]: i32) -> i32
+// CHECK-NEXT:   %[[VAL:[A-Za-z0-9_]*]] = math.cttz %[[ARG]] : i32
+// CHECK-NEXT:   return %[[VAL]] : i32
+// CHECK-NEXT: }
+
+int do_ctz(int i) {
+  return __builtin_ctz(i);
+}
+
+// CHECK:      func.func @do_ctzl(%[[ARG:[A-Za-z0-9_]*]]: i64) -> i32
+// CHECK-NEXT:   %[[VAL_0:[A-Za-z0-9_]*]] = math.cttz %[[ARG]] : i64
+// CHECK-NEXT:   %[[VAL_1:[A-Za-z0-9_]*]] = arith.trunci %[[VAL_0]] : i64 to i32
+// CHECK-NEXT:   return %[[VAL_1]] : i32
+// CHECK-NEXT: }
+
+int do_ctzl(unsigned long i) {
+  return __builtin_ctzl(i);
+}
+
+// CHECK:      func.func @do_ctzll(%[[ARG:[A-Za-z0-9_]*]]: i64) -> i32
+// CHECK-NEXT:   %[[VAL_0:[A-Za-z0-9_]*]] = math.cttz %[[ARG]] : i64
+// CHECK-NEXT:   %[[VAL_1:[A-Za-z0-9_]*]] = arith.trunci %[[VAL_0]] : i64 to i32
+// CHECK-NEXT:   return %[[VAL_1]] : i32
+// CHECK-NEXT: }
+
+int do_ctzll(unsigned long long i) {
+  return __builtin_ctzl(i);
+}