[CIR] Implement lowering of int-to-bool casts

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -385,13 +385,13 @@ mlir::LogicalResult CIRToLLVMCastOpLowering::matchAndRewrite(
     break;
   }
   case cir::CastKind::int_to_bool: {
-    assert(!cir::MissingFeatures::opCmp());
-    mlir::Type dstType = castOp.getResult().getType();
-    mlir::Type llvmDstType = getTypeConverter()->convertType(dstType);
-    auto zeroBool = rewriter.create<mlir::LLVM::ConstantOp>(
-        castOp.getLoc(), llvmDstType, mlir::BoolAttr::get(getContext(), false));
-    rewriter.replaceOp(castOp, zeroBool);
-    return castOp.emitError() << "NYI int_to_bool cast";
+    mlir::Value llvmSrcVal = adaptor.getOperands().front();
+    mlir::Value zeroInt = rewriter.create<mlir::LLVM::ConstantOp>(
+        castOp.getLoc(), llvmSrcVal.getType(),
+        mlir::IntegerAttr::get(llvmSrcVal.getType(), 0));
+    rewriter.replaceOpWithNewOp<mlir::LLVM::ICmpOp>(
+        castOp, mlir::LLVM::ICmpPredicate::ne, llvmSrcVal, zeroInt);
+    break;
   }
   case cir::CastKind::integral: {
     mlir::Type srcType = castOp.getSrc().getType();

clang/test/CIR/CodeGen/int-to-bool.cpp

@@ -0,0 +1,74 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+bool f1(unsigned char c) {
+  return c;
+}
+
+// CIR: cir.func @f1
+// CIR:   cir.cast(int_to_bool, %{{.*}} : !u8i), !cir.bool
+
+// Note: The full zext/store/load/trunc sequence is checked here to show what
+// CIR is being lowered to. There's no need to check it for every function since
+// the lowering is the same for all of them.
+
+// LLVM: define i1 @f1
+// LLVM:   %[[CMP:.*]] = icmp ne i8 %4, 0
+// LLVM:   %[[ZEXT:.*]] = zext i1 %[[CMP]] to i8
+// LLVM:   store i8 %[[ZEXT]], ptr %{{.*}}
+// LLVM:   %[[LOAD:.*]] = load i8, ptr %{{.*}}
+// LLVM:   %[[TRUNC:.*]] = trunc i8 %[[LOAD]] to i1
+// LLVM:   ret i1 %[[TRUNC]]
+
+// OGCG: define{{.*}} i1 @_Z2f1h
+// OGCG:   %[[CMP:.*]] = icmp ne i8 %{{.*}}, 0
+// OGCG:   ret i1 %[[CMP]]
+
+bool f2(short s) {
+  return s;
+}
+
+// CIR: cir.func @f2
+// CIR:   cir.cast(int_to_bool, %{{.*}} : !s16i), !cir.bool
+
+// LLVM: define i1 @f2
+// LLVM:   %[[CMP:.*]] = icmp ne i16 %4, 0
+// LLVM:   %[[ZEXT:.*]] = zext i1 %[[CMP]] to i8
+
+// OGCG: define{{.*}} i1 @_Z2f2s
+// OGCG:   %[[CMP:.*]] = icmp ne i16 %{{.*}}, 0
+// OGCG:   ret i1 %[[CMP]]
+
+bool f3(unsigned u) {
+  return u;
+}
+
+// CIR: cir.func @f3
+// CIR:   cir.cast(int_to_bool, %{{.*}} : !u32i), !cir.bool
+
+// LLVM: define i1 @f3
+// LLVM:   %[[CMP:.*]] = icmp ne i32 %4, 0
+// LLVM:   %[[ZEXT:.*]] = zext i1 %[[CMP]] to i8
+
+// OGCG: define{{.*}} i1 @_Z2f3j
+// OGCG:   %[[CMP:.*]] = icmp ne i32 %{{.*}}, 0
+// OGCG:   ret i1 %[[CMP]]
+
+bool f4(long l) {
+  return l;
+}
+
+// CIR: cir.func @f4
+// CIR:   cir.cast(int_to_bool, %{{.*}} : !s64i), !cir.bool
+
+// LLVM: define i1 @f4
+// LLVM:   %[[CMP:.*]] = icmp ne i64 %4, 0
+// LLVM:   %[[ZEXT:.*]] = zext i1 %[[CMP]] to i8
+
+// OGCG: define{{.*}} i1 @_Z2f4l
+// OGCG:   %[[CMP:.*]] = icmp ne i64 %{{.*}}, 0
+// OGCG:   ret i1 %[[CMP]]

clang/test/CIR/Lowering/cast.cir

@@ -47,6 +47,9 @@ module {
     %21 = cir.load %20 : !cir.ptr<!s16i>, !s16i
     %22 = cir.cast(integral, %21 : !s16i), !u64i
     // CHECK: %[[TMP:[0-9]+]] = llvm.sext %{{[0-9]+}} : i16 to i64
+    %33 = cir.cast(int_to_bool, %arg1 : !s32i), !cir.bool
+    // CHECK: %[[#ZERO:]] = llvm.mlir.constant(0 : i32) : i32
+    // CHECK: %[[#CMP:]] = llvm.icmp "ne" %arg1, %[[#ZERO]] : i32
 
     // Pointer casts.
     cir.store %16, %6 : !s64i, !cir.ptr<!s64i>