commit fb91483e48fe6cfa21edc613f266e27bd6bf9dbf (tree)
parent e584558bd8533ce91d1683cdbc6b77d7bb652acf
Author: Veikka Tuominen <git@vexu.eu>
Date: Mon, 19 Sep 2022 13:11:19 +0300
Sema: do not use coerceCompatiblePtr for ptrCast
Diffstat:
5 files changed, 75 insertions(+), 34 deletions(-)
diff --git a/src/Sema.zig b/src/Sema.zig
@@ -17772,6 +17772,7 @@ fn zirErrSetCast(sema: *Sema, block: *Block, extended: Zir.Inst.Extended.InstDat
fn zirPtrCast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
const inst_data = sema.code.instructions.items(.data)[inst].pl_node;
+ const src = inst_data.src();
const dest_ty_src: LazySrcLoc = .{ .node_offset_builtin_call_arg0 = inst_data.src_node };
const operand_src: LazySrcLoc = .{ .node_offset_builtin_call_arg1 = inst_data.src_node };
const extra = sema.code.extraData(Zir.Inst.Bin, inst_data.payload_index).data;
@@ -17783,6 +17784,15 @@ fn zirPtrCast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
try sema.checkPtrType(block, dest_ty_src, dest_ty);
try sema.checkPtrOperand(block, operand_src, operand_ty);
+ const operand_info = operand_ty.ptrInfo().data;
+ const dest_info = dest_ty.ptrInfo().data;
+ if (!operand_info.mutable and dest_info.mutable) {
+ return sema.fail(block, src, "cast discards const qualifier", .{});
+ }
+ if (operand_info.@"volatile" and !dest_info.@"volatile") {
+ return sema.fail(block, src, "cast discards volatile qualifier", .{});
+ }
+
const dest_is_slice = dest_ty.isSlice();
const operand_is_slice = operand_ty.isSlice();
if (dest_is_slice and !operand_is_slice) {
@@ -17793,15 +17803,6 @@ fn zirPtrCast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
else
operand;
- if (try sema.resolveMaybeUndefVal(block, operand_src, operand)) |operand_val| {
- if (!dest_ty.ptrAllowsZero() and operand_val.isUndef()) {
- return sema.failWithUseOfUndef(block, operand_src);
- }
- if (!dest_ty.ptrAllowsZero() and operand_val.isNull()) {
- return sema.fail(block, operand_src, "null pointer casted to type {}", .{dest_ty.fmt(sema.mod)});
- }
- }
-
const dest_elem_ty = dest_ty.elemType2();
try sema.resolveTypeLayout(block, dest_ty_src, dest_elem_ty);
const dest_align = dest_ty.ptrAlignment(target);
@@ -17835,7 +17836,47 @@ fn zirPtrCast(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
}
}
- return sema.coerceCompatiblePtrs(block, aligned_dest_ty, ptr, operand_src);
+ if (dest_align > operand_align) {
+ const msg = msg: {
+ const msg = try sema.errMsg(block, src, "cast increases pointer alignment", .{});
+ errdefer msg.destroy(sema.gpa);
+
+ try sema.errNote(block, operand_src, msg, "'{}' has alignment '{d}'", .{
+ operand_ty.fmt(sema.mod), operand_align,
+ });
+ try sema.errNote(block, dest_ty_src, msg, "'{}' has alignment '{d}'", .{
+ dest_ty.fmt(sema.mod), dest_align,
+ });
+ break :msg msg;
+ };
+ return sema.failWithOwnedErrorMsg(msg);
+ }
+
+ if (try sema.resolveMaybeUndefVal(block, operand_src, operand)) |operand_val| {
+ if (!dest_ty.ptrAllowsZero() and operand_val.isUndef()) {
+ return sema.failWithUseOfUndef(block, operand_src);
+ }
+ if (!dest_ty.ptrAllowsZero() and operand_val.isNull()) {
+ return sema.fail(block, operand_src, "null pointer casted to type {}", .{dest_ty.fmt(sema.mod)});
+ }
+ return sema.addConstant(aligned_dest_ty, operand_val);
+ }
+
+ try sema.requireRuntimeBlock(block, src, null);
+ if (block.wantSafety() and operand_ty.ptrAllowsZero() and !dest_ty.ptrAllowsZero() and
+ try sema.typeHasRuntimeBits(block, sema.src, dest_ty.elemType2()))
+ {
+ const ptr_int = try block.addUnOp(.ptrtoint, ptr);
+ const is_non_zero = try block.addBinOp(.cmp_neq, ptr_int, .zero_usize);
+ const ok = if (operand_is_slice) ok: {
+ const len = try sema.analyzeSliceLen(block, operand_src, operand);
+ const len_zero = try block.addBinOp(.cmp_eq, len, .zero_usize);
+ break :ok try block.addBinOp(.bit_or, len_zero, is_non_zero);
+ } else is_non_zero;
+ try sema.addSafetyCheck(block, ok, .cast_to_null);
+ }
+
+ return block.addBitCast(aligned_dest_ty, ptr);
}
fn zirTruncate(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air.Inst.Ref {
diff --git a/test/cases/compile_errors/increase_pointer_alignment_in_ptrCast.zig b/test/cases/compile_errors/increase_pointer_alignment_in_ptrCast.zig
@@ -0,0 +1,13 @@
+export fn entry() u32 {
+ var bytes: [4]u8 = [_]u8{0x01, 0x02, 0x03, 0x04};
+ const ptr = @ptrCast(*u32, &bytes[0]);
+ return ptr.*;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:17: error: cast increases pointer alignment
+// :3:32: note: '*u8' has alignment '1'
+// :3:26: note: '*u32' has alignment '4'
diff --git a/test/cases/compile_errors/ptrCast_discards_const_qualifier.zig b/test/cases/compile_errors/ptrCast_discards_const_qualifier.zig
@@ -0,0 +1,11 @@
+export fn entry() void {
+ const x: i32 = 1234;
+ const y = @ptrCast(*i32, &x);
+ _ = y;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :3:15: error: cast discards const qualifier
diff --git a/test/cases/compile_errors/stage1/obj/increase_pointer_alignment_in_ptrCast.zig b/test/cases/compile_errors/stage1/obj/increase_pointer_alignment_in_ptrCast.zig
@@ -1,13 +0,0 @@
-export fn entry() u32 {
- var bytes: [4]u8 = [_]u8{0x01, 0x02, 0x03, 0x04};
- const ptr = @ptrCast(*u32, &bytes[0]);
- return ptr.*;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:3:17: error: cast increases pointer alignment
-// tmp.zig:3:38: note: '*u8' has alignment 1
-// tmp.zig:3:26: note: '*u32' has alignment 4
diff --git a/test/cases/compile_errors/stage1/obj/ptrCast_discards_const_qualifier.zig b/test/cases/compile_errors/stage1/obj/ptrCast_discards_const_qualifier.zig
@@ -1,11 +0,0 @@
-export fn entry() void {
- const x: i32 = 1234;
- const y = @ptrCast(*i32, &x);
- _ = y;
-}
-
-// error
-// backend=stage1
-// target=native
-//
-// tmp.zig:3:15: error: cast discards const qualifier
