[CIR][CIRGen] Support check for zero-init pointers (#441)

llvm · Nov 2, 2024 · 436d728 · 436d728
1 parent 4e63ef1
commit 436d728
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Showing 5 changed files with 42 additions and 5 deletions.
diff --git a/clang/lib/CIR/CodeGen/CIRGenBuilder.h b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
@@ -550,7 +550,9 @@ class CIRGenBuilderTy : public CIRBaseBuilderTy {
 
   mlir::cir::ConstantOp getZero(mlir::Location loc, mlir::Type ty) {
     // TODO: dispatch creation for primitive types.
-    assert(ty.isa<mlir::cir::StructType>() && "NYI for other types");
+    assert(
+        (ty.isa<mlir::cir::StructType>() || ty.isa<mlir::cir::ArrayType>()) &&
+        "NYI for other types");
     return create<mlir::cir::ConstantOp>(loc, ty, getZeroAttr(ty));
   }
 

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprAgg.cpp b/clang/lib/CIR/CodeGen/CIRGenExprAgg.cpp
@@ -649,10 +649,9 @@ static bool isSimpleZero(const Expr *E, CIRGenFunction &CGF) {
     return true;
   // (int*)0 - Null pointer expressions.
   if (const CastExpr *ICE = dyn_cast<CastExpr>(E)) {
-    llvm_unreachable("NYI");
-    // return ICE->getCastKind() == CK_NullToPointer &&
-    //        CGF.getTypes().isPointerZeroInitializable(E->getType()) &&
-    //        !E->HasSideEffects(CGF.getContext());
+    return ICE->getCastKind() == CK_NullToPointer &&
+           CGF.getTypes().isPointerZeroInitializable(E->getType()) &&
+           !E->HasSideEffects(CGF.getContext());
   }
   // '\0'
   if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))

diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.cpp b/clang/lib/CIR/CodeGen/CIRGenTypes.cpp
@@ -850,6 +850,11 @@ CIRGenTypes::getCIRGenRecordLayout(const RecordDecl *RD) {
   return *I->second;
 }
 
+bool CIRGenTypes::isPointerZeroInitializable(clang::QualType T) {
+  assert((T->isAnyPointerType() || T->isBlockPointerType()) && "Invalid type");
+  return isZeroInitializable(T);
+}
+
 bool CIRGenTypes::isZeroInitializable(QualType T) {
   if (T->getAs<PointerType>())
     return Context.getTargetNullPointerValue(T) == 0;

diff --git a/clang/lib/CIR/CodeGen/CIRGenTypes.h b/clang/lib/CIR/CodeGen/CIRGenTypes.h
@@ -149,6 +149,11 @@ class CIRGenTypes {
   /// Return whether a type can be zero-initialized (in the C++ sense) with an
   /// LLVM zeroinitializer.
   bool isZeroInitializable(clang::QualType T);
+
+  /// Check if the pointer type can be zero-initialized (in the C++ sense)
+  /// with an LLVM zeroinitializer.
+  bool isPointerZeroInitializable(clang::QualType T);
+
   /// Return whether a record type can be zero-initialized (in the C++ sense)
   /// with an LLVM zeroinitializer.
   bool isZeroInitializable(const clang::RecordDecl *RD);

diff --git a/clang/test/CIR/CodeGen/array-init.c b/clang/test/CIR/CodeGen/array-init.c
@@ -1,5 +1,31 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-cir %s -o - | FileCheck %s
 
+typedef struct {
+  int a;
+  long b;
+} T;
+
+void buz(int x) {
+  T arr[] = { {0, x}, {0, 0} };
+}
+// CHECK: cir.func @buz
+// CHECK-NEXT: [[X_ALLOCA:%.*]] = cir.alloca !s32i, cir.ptr <!s32i>, ["x", init] {alignment = 4 : i64}
+// CHECK-NEXT: [[ARR:%.*]] = cir.alloca !cir.array<!ty_22T22 x 2>, cir.ptr <!cir.array<!ty_22T22 x 2>>, ["arr", init] {alignment = 16 : i64}
+// CHECK-NEXT: cir.store %arg0, [[X_ALLOCA]] : !s32i, cir.ptr <!s32i>
+// CHECK-NEXT: [[ARR_INIT:%.*]] = cir.const(#cir.zero : !cir.array<!ty_22T22 x 2>) : !cir.array<!ty_22T22 x 2>
+// CHECK-NEXT: cir.store [[ARR_INIT]], [[ARR]] : !cir.array<!ty_22T22 x 2>, cir.ptr <!cir.array<!ty_22T22 x 2>>
+// CHECK-NEXT: [[FI_EL:%.*]] = cir.cast(array_to_ptrdecay, [[ARR]] : !cir.ptr<!cir.array<!ty_22T22 x 2>>), !cir.ptr<!ty_22T22>
+// CHECK-NEXT: [[A_STORAGE0:%.*]] = cir.get_member [[FI_EL]][0] {name = "a"} : !cir.ptr<!ty_22T22> -> !cir.ptr<!s32i>
+// CHECK-NEXT: [[B_STORAGE0:%.*]] = cir.get_member [[FI_EL]][1] {name = "b"} : !cir.ptr<!ty_22T22> -> !cir.ptr<!s64i>
+// CHECK-NEXT: [[X_VAL:%.*]] = cir.load [[X_ALLOCA]] : cir.ptr <!s32i>, !s32i
+// CHECK-NEXT: [[X_CASTED:%.*]] = cir.cast(integral, [[X_VAL]] : !s32i), !s64i
+// CHECK-NEXT: cir.store [[X_CASTED]], [[B_STORAGE0]] : !s64i, cir.ptr <!s64i>
+// CHECK-NEXT: [[ONE:%.*]] = cir.const(#cir.int<1> : !s64i) : !s64i
+// CHECK-NEXT: [[SE_EL:%.*]] = cir.ptr_stride([[FI_EL]] : !cir.ptr<!ty_22T22>, [[ONE]] : !s64i), !cir.ptr<!ty_22T22>
+// CHECK-NEXT: [[A_STORAGE1:%.*]] = cir.get_member [[SE_EL]][0] {name = "a"} : !cir.ptr<!ty_22T22> -> !cir.ptr<!s32i>
+// CHECK-NEXT: [[B_STORAGE1:%.*]] = cir.get_member [[SE_EL]][1] {name = "b"} : !cir.ptr<!ty_22T22> -> !cir.ptr<!s64i>
+// CHECK-NEXT: cir.return
+
 void foo() {
   double bar[] = {9,8,7};
 }