[CIR] Add integer result type for cir.global_view (#1248)

This PR updates the `#cir.global_view` attribute and make it accept
integer types as its result type.

Author: Lancern

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -607,11 +607,16 @@ def GlobalViewAttr : CIR_Attr<"GlobalView", "global_view", [TypedAttrInterface]>
     for `!cir.ptr`, an offset is applied. The first index is relative to the
     original symbol type, not the produced one.
 
+    The result type of this attribute may be an integer type. In such a case,
+    the pointer to the referenced global is casted to an integer and this
+    attribute represents the casted result.
+
     Example:
 
     ```
       cir.global external @s = @".str2": !cir.ptr<i8>
       cir.global external @x = #cir.global_view<@s> : !cir.ptr<i8>
+      cir.global external @s_addr = #cir.global_view<@s> : !s64i
 
       cir.global external @rgb = #cir.const_array<[0 : i8, -23 : i8, 33 : i8] : !cir.array<i8 x 3>>
       cir.global external @elt_ptr = #cir.global_view<@rgb, [1]> : !cir.ptr<i8>

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

@@ -698,17 +698,25 @@ lowerCirAttrAsValue(mlir::Operation *parentOp, cir::GlobalViewAttr globalAttr,
                                                 indices, true);
   }
 
-  auto ptrTy = mlir::dyn_cast<cir::PointerType>(globalAttr.getType());
-  assert(ptrTy && "Expecting pointer type in GlobalViewAttr");
-  auto llvmEltTy =
-      convertTypeForMemory(*converter, dataLayout, ptrTy.getPointee());
+  if (auto intTy = mlir::dyn_cast<cir::IntType>(globalAttr.getType())) {
+    auto llvmDstTy = converter->convertType(globalAttr.getType());
+    return rewriter.create<mlir::LLVM::PtrToIntOp>(parentOp->getLoc(),
+                                                   llvmDstTy, addrOp);
+  }
+
+  if (auto ptrTy = mlir::dyn_cast<cir::PointerType>(globalAttr.getType())) {
+    auto llvmEltTy =
+        convertTypeForMemory(*converter, dataLayout, ptrTy.getPointee());
 
-  if (llvmEltTy == sourceType)
-    return addrOp;
+    if (llvmEltTy == sourceType)
+      return addrOp;
 
-  auto llvmDstTy = converter->convertType(globalAttr.getType());
-  return rewriter.create<mlir::LLVM::BitcastOp>(parentOp->getLoc(), llvmDstTy,
-                                                addrOp);
+    auto llvmDstTy = converter->convertType(globalAttr.getType());
+    return rewriter.create<mlir::LLVM::BitcastOp>(parentOp->getLoc(), llvmDstTy,
+                                                  addrOp);
+  }
+
+  llvm_unreachable("Expecting pointer or integer type for GlobalViewAttr");
 }
 
 /// Switches on the type of attribute and calls the appropriate conversion.
@@ -1752,6 +1760,14 @@ mlir::LogicalResult CIRToLLVMConstantOpLowering::matchAndRewrite(
     attr = rewriter.getIntegerAttr(typeConverter->convertType(op.getType()),
                                    value);
   } else if (mlir::isa<cir::IntType>(op.getType())) {
+    // Lower GlobalAddrAttr to llvm.mlir.addressof + llvm.mlir.ptrtoint
+    if (auto ga = mlir::dyn_cast<cir::GlobalViewAttr>(op.getValue())) {
+      auto newOp =
+          lowerCirAttrAsValue(op, ga, rewriter, getTypeConverter(), dataLayout);
+      rewriter.replaceOp(op, newOp);
+      return mlir::success();
+    }
+
     attr = rewriter.getIntegerAttr(
         typeConverter->convertType(op.getType()),
         mlir::cast<cir::IntAttr>(op.getValue()).getValue());

clang/test/CIR/Lowering/globals.cir

@@ -27,15 +27,22 @@ module {
   cir.global external @alpha = #cir.const_array<[#cir.int<97> : !s8i, #cir.int<98> : !s8i, #cir.int<99> : !s8i, #cir.int<0> : !s8i]> : !cir.array<!s8i x 4>
   cir.global "private" constant internal @".str" = #cir.const_array<"example\00" : !cir.array<!s8i x 8>> : !cir.array<!s8i x 8> {alignment = 1 : i64}
   cir.global external @s = #cir.global_view<@".str"> : !cir.ptr<!s8i>
+  cir.global external @s_addr = #cir.global_view<@".str"> : !u64i
   // MLIR: llvm.mlir.global internal constant @".str"("example\00")
   // MLIR-SAME: {addr_space = 0 : i32, alignment = 1 : i64}
   // MLIR: llvm.mlir.global external @s() {addr_space = 0 : i32} : !llvm.ptr {
   // MLIR:   %0 = llvm.mlir.addressof @".str" : !llvm.ptr
   // MLIR:   %1 = llvm.bitcast %0 : !llvm.ptr to !llvm.ptr
   // MLIR:   llvm.return %1 : !llvm.ptr
   // MLIR: }
+  // MLIR: llvm.mlir.global external @s_addr() {addr_space = 0 : i32} : i64 {
+  // MLIR:   %0 = llvm.mlir.addressof @".str" : !llvm.ptr
+  // MLIR:   %1 = llvm.ptrtoint %0 : !llvm.ptr to i64
+  // MLIR:   llvm.return %1 : i64
+  // MLIR: }
   // LLVM: @.str = internal constant [8 x i8] c"example\00"
   // LLVM: @s = global ptr @.str
+  // LLVM: @s_addr = global i64 ptrtoint (ptr @.str to i64)
   cir.global external @aPtr = #cir.global_view<@a> : !cir.ptr<!s32i>
   // MLIR: llvm.mlir.global external @aPtr() {addr_space = 0 : i32} : !llvm.ptr {
   // MLIR:   %0 = llvm.mlir.addressof @a : !llvm.ptr
@@ -198,4 +205,17 @@ module {
   }
   // MLIR:  %0 = llvm.mlir.addressof @zero_array
 
+  cir.func @global_view_as_integer() -> !u64i {
+    %0 = cir.const #cir.global_view<@".str"> : !u64i
+    cir.return %0 : !u64i
+  }
+  // MLIR-LABEL: @global_view_as_integer
+  // MLIR-NEXT:    %0 = llvm.mlir.addressof @".str" : !llvm.ptr
+  // MLIR-NEXT:    %1 = llvm.ptrtoint %0 : !llvm.ptr to i64
+  // MLIR-NEXT:    llvm.return %1 : i64
+  // MLIR-NEXT:  }
+  // LLVM-LABEL: @global_view_as_integer
+  // LLVM-NEXT:    ret i64 ptrtoint (ptr @.str to i64)
+  // LLVM-NEXT:  }
+
 }