[CIR] Upstream handling of integral-to-pointer casts

clang/include/clang/CIR/Dialect/IR/CIRDataLayout.h

@@ -14,6 +14,11 @@
 
 #include "mlir/Dialect/DLTI/DLTI.h"
 #include "mlir/IR/BuiltinOps.h"
+#include "clang/CIR/Dialect/IR/CIRAttrs.h"
+#include "clang/CIR/Dialect/IR/CIRTypes.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/Support/Alignment.h"
+#include "llvm/Support/TypeSize.h"
 
 namespace cir {
 
@@ -81,6 +86,19 @@ class CIRDataLayout {
   }
 
   llvm::TypeSize getTypeSizeInBits(mlir::Type ty) const;
+
+  llvm::TypeSize getPointerTypeSizeInBits(mlir::Type Ty) const {
+    assert(mlir::isa<cir::PointerType>(Ty) &&
+           "This should only be called with a pointer type");
+    return layout.getTypeSizeInBits(Ty);
+  }
+
+  mlir::Type getIntPtrType(mlir::Type Ty) const {
+    assert(mlir::isa<cir::PointerType>(Ty) && "Expected pointer type");
+    auto IntTy =
+        cir::IntType::get(Ty.getContext(), getPointerTypeSizeInBits(Ty), false);
+    return IntTy;
+  }
 };
 
 } // namespace cir

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -1889,6 +1889,25 @@ mlir::Value ScalarExprEmitter::VisitCastExpr(CastExpr *ce) {
     }
     return v;
   }
+  case CK_IntegralToPointer: {
+    auto DestCIRTy = cgf.convertType(destTy);
+    mlir::Value Src = Visit(const_cast<Expr *>(subExpr));
+
+    // Properly resize by casting to an int of the same size as the pointer.
+    // Clang's IntegralToPointer includes 'bool' as the source, but in CIR
+    // 'bool' is not an integral type.  So check the source type to get the
+    // correct CIR conversion.
+    auto MiddleTy = cgf.cgm.getDataLayout().getIntPtrType(DestCIRTy);
+    auto MiddleVal = builder.createCast(subExpr->getType()->isBooleanType()
+                                            ? cir::CastKind::bool_to_int
+                                            : cir::CastKind::integral,
+                                        Src, MiddleTy);
+
+    if (cgf.cgm.getCodeGenOpts().StrictVTablePointers)
+      llvm_unreachable("NYI");
+
+    return builder.createIntToPtr(MiddleVal, DestCIRTy);
+  }
 
   case CK_ArrayToPointerDecay:
     return cgf.emitArrayToPointerDecay(subExpr).getPointer();

clang/test/CIR/CodeGen/cast.cpp

@@ -131,3 +131,25 @@ void bitcast() {
 
 // LLVM: %[[D_VEC:.*]] = load <2 x double>, ptr {{.*}}, align 16
 // LLVM: %[[I_VEC:.*]] = bitcast <2 x double> %[[D_VEC]] to <4 x i32>
+
+void f(long int start) {
+  void *p = (void*)start;
+}
+// CIR: %[[L:.*]] = cir.load {{.*}} : !cir.ptr<!s64i>, !s64i
+// CIR: %[[MID:.*]] = cir.cast integral %[[L]] : !s64i -> !u64i
+// CIR:          cir.cast int_to_ptr %[[MID]] : !u64i -> !cir.ptr<!void>
+
+struct A { int x; };
+
+void int_cast(long ptr) {
+  ((A *)ptr)->x = 0;
+}
+// CIR: cir.cast int_to_ptr {{.*}} : !u64i -> !cir.ptr<!rec_A>
+// LLVM: inttoptr {{.*}} to ptr
+
+void null_cast(long) {
+  *(int *)0 = 0;
+  ((A *)0)->x = 0;
+}
+// CIR: #cir.ptr<null> : !cir.ptr<!s32i>
+// CIR: #cir.ptr<null> : !cir.ptr<!rec_A>