commit aaf46187ab7bf23c87a275e2755a9bd01f3c93cf (tree)
parent fa08e49f839d47441af9a1bcf23dc1701849379e
Author: Andrew Kelley <andrew@ziglang.org>
Date: Mon, 9 Oct 2023 22:06:49 -0700
Merge pull request #17391 from xxxbxxx/load-i4
codegen/llvm: truncate padding bits when loading a non-byte-sized value
Diffstat:
5 files changed, 321 insertions(+), 12 deletions(-)
diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
@@ -4353,9 +4353,21 @@ fn intcast(func: *CodeGen, operand: WValue, given: Type, wanted: Type) InnerErro
if (op_bits > 32 and op_bits <= 64 and wanted_bits == 32) {
try func.emitWValue(operand);
try func.addTag(.i32_wrap_i64);
+ if (given.isSignedInt(mod) and wanted_bitsize < 32)
+ return func.wrapOperand(.{ .stack = {} }, wanted)
+ else
+ return WValue{ .stack = {} };
} else if (op_bits == 32 and wanted_bits > 32 and wanted_bits <= 64) {
- try func.emitWValue(operand);
+ const operand32 = if (given_bitsize < 32 and wanted.isSignedInt(mod))
+ try func.signExtendInt(operand, given)
+ else
+ operand;
+ try func.emitWValue(operand32);
try func.addTag(if (wanted.isSignedInt(mod)) .i64_extend_i32_s else .i64_extend_i32_u);
+ if (given.isSignedInt(mod) and wanted_bitsize < 64)
+ return func.wrapOperand(.{ .stack = {} }, wanted)
+ else
+ return WValue{ .stack = {} };
} else if (wanted_bits == 128) {
// for 128bit integers we store the integer in the virtual stack, rather than a local
const stack_ptr = try func.allocStack(wanted);
@@ -4381,8 +4393,6 @@ fn intcast(func: *CodeGen, operand: WValue, given: Type, wanted: Type) InnerErro
}
return stack_ptr;
} else return func.load(operand, wanted, 0);
-
- return WValue{ .stack = {} };
}
fn airIsNull(func: *CodeGen, inst: Air.Inst.Index, opcode: wasm.Opcode, op_kind: enum { value, ptr }) InnerError!void {
diff --git a/src/codegen/llvm.zig b/src/codegen/llvm.zig
@@ -6179,7 +6179,6 @@ pub const FuncGen = struct {
const elem_alignment = elem_ty.abiAlignment(mod).toLlvm();
return self.loadByRef(elem_ptr, elem_ty, elem_alignment, .normal);
} else {
- const elem_llvm_ty = try o.lowerType(elem_ty);
if (Air.refToIndex(bin_op.lhs)) |lhs_index| {
if (self.air.instructions.items(.tag)[lhs_index] == .load) {
const load_data = self.air.instructions.items(.data)[lhs_index];
@@ -6201,7 +6200,7 @@ pub const FuncGen = struct {
&indices,
"",
);
- return self.wip.load(.normal, elem_llvm_ty, gep, .default, "");
+ return self.loadTruncate(.normal, elem_ty, gep, .default);
},
else => {},
}
@@ -6210,7 +6209,7 @@ pub const FuncGen = struct {
}
const elem_ptr =
try self.wip.gep(.inbounds, array_llvm_ty, array_llvm_val, &indices, "");
- return self.wip.load(.normal, elem_llvm_ty, elem_ptr, .default, "");
+ return self.loadTruncate(.normal, elem_ty, elem_ptr, .default);
}
}
@@ -6378,13 +6377,12 @@ pub const FuncGen = struct {
const payload_index = @intFromBool(layout.tag_align.compare(.gte, layout.payload_align));
const field_ptr =
try self.wip.gepStruct(union_llvm_ty, struct_llvm_val, payload_index, "");
- const llvm_field_ty = try o.lowerType(field_ty);
const payload_alignment = layout.payload_align.toLlvm();
if (isByRef(field_ty, mod)) {
if (canElideLoad(self, body_tail)) return field_ptr;
return self.loadByRef(field_ptr, field_ty, payload_alignment, .normal);
} else {
- return self.wip.load(.normal, llvm_field_ty, field_ptr, payload_alignment, "");
+ return self.loadTruncate(.normal, field_ty, field_ptr, payload_alignment);
}
},
else => unreachable,
@@ -10219,8 +10217,7 @@ pub const FuncGen = struct {
return fg.loadByRef(payload_ptr, payload_ty, payload_alignment, .normal);
}
- const payload_llvm_ty = try o.lowerType(payload_ty);
- return fg.wip.load(.normal, payload_llvm_ty, payload_ptr, payload_alignment, "");
+ return fg.loadTruncate(.normal, payload_ty, payload_ptr, payload_alignment);
}
assert(!isByRef(payload_ty, mod));
@@ -10321,6 +10318,56 @@ pub const FuncGen = struct {
}
}
+ /// Load a value and, if needed, mask out padding bits for non byte-sized integer values.
+ fn loadTruncate(
+ fg: *FuncGen,
+ access_kind: Builder.MemoryAccessKind,
+ payload_ty: Type,
+ payload_ptr: Builder.Value,
+ payload_alignment: Builder.Alignment,
+ ) !Builder.Value {
+ // from https://llvm.org/docs/LangRef.html#load-instruction :
+ // "When loading a value of a type like i20 with a size that is not an integral number of bytes, the result is undefined if the value was not originally written using a store of the same type. "
+ // => so load the byte aligned value and trunc the unwanted bits.
+
+ const o = fg.dg.object;
+ const mod = o.module;
+ const payload_llvm_ty = try o.lowerType(payload_ty);
+ const abi_size = payload_ty.abiSize(mod);
+
+ // llvm bug workarounds:
+ const workaround_explicit_mask = o.target.cpu.arch == .powerpc and abi_size >= 4;
+ const workaround_disable_truncate = o.target.cpu.arch == .wasm32 and abi_size >= 4;
+
+ if (workaround_disable_truncate) {
+ // see https://github.com/llvm/llvm-project/issues/64222
+ // disable the truncation codepath for larger that 32bits value - with this heuristic, the backend passes the test suite.
+ return try fg.wip.load(access_kind, payload_llvm_ty, payload_ptr, payload_alignment, "");
+ }
+
+ const load_llvm_ty = if (payload_ty.isAbiInt(mod))
+ try o.builder.intType(@intCast(abi_size * 8))
+ else
+ payload_llvm_ty;
+ const loaded = try fg.wip.load(access_kind, load_llvm_ty, payload_ptr, payload_alignment, "");
+ const shifted = if (payload_llvm_ty != load_llvm_ty and o.target.cpu.arch.endian() == .Big)
+ try fg.wip.bin(.lshr, loaded, try o.builder.intValue(
+ load_llvm_ty,
+ (payload_ty.abiSize(mod) - (std.math.divCeil(u64, payload_ty.bitSize(mod), 8) catch unreachable)) * 8,
+ ), "")
+ else
+ loaded;
+
+ const anded = if (workaround_explicit_mask and payload_llvm_ty != load_llvm_ty) blk: {
+ // this is rendundant with llvm.trunc. But without it, llvm17 emits invalid code for powerpc.
+ var mask_val = try o.builder.intConst(payload_llvm_ty, -1);
+ mask_val = try o.builder.castConst(.zext, mask_val, load_llvm_ty);
+ break :blk try fg.wip.bin(.@"and", shifted, mask_val.toValue(), "");
+ } else shifted;
+
+ return fg.wip.conv(.unneeded, anded, payload_llvm_ty, "");
+ }
+
/// Load a by-ref type by constructing a new alloca and performing a memcpy.
fn loadByRef(
fg: *FuncGen,
@@ -10378,7 +10425,7 @@ pub const FuncGen = struct {
if (isByRef(elem_ty, mod)) {
return self.loadByRef(ptr, elem_ty, ptr_alignment, access_kind);
}
- return self.wip.load(access_kind, try o.lowerType(elem_ty), ptr, ptr_alignment, "");
+ return self.loadTruncate(access_kind, elem_ty, ptr, ptr_alignment);
}
const containing_int_ty = try o.builder.intType(@intCast(info.packed_offset.host_size * 8));
diff --git a/test/behavior/cast_int.zig b/test/behavior/cast_int.zig
@@ -1,6 +1,7 @@
const builtin = @import("builtin");
const std = @import("std");
const expect = std.testing.expect;
+const expectEqual = std.testing.expectEqual;
const maxInt = std.math.maxInt;
test "@intCast i32 to u7" {
@@ -28,3 +29,197 @@ test "coerce i8 to i32 and @intCast back" {
var y2: i8 = -5;
try expect(y2 == @as(i8, @intCast(x2)));
}
+
+test "coerce non byte-sized integers accross 32bits boundary" {
+ {
+ var v: u21 = 6417;
+ const a: u32 = v;
+ const b: u64 = v;
+ const c: u64 = a;
+ var w: u64 = 0x1234567812345678;
+ const d: u21 = @truncate(w);
+ const e: u60 = d;
+ try expectEqual(@as(u32, 6417), a);
+ try expectEqual(@as(u64, 6417), b);
+ try expectEqual(@as(u64, 6417), c);
+ try expectEqual(@as(u21, 0x145678), d);
+ try expectEqual(@as(u60, 0x145678), e);
+ }
+
+ {
+ var v: u10 = 234;
+ const a: u32 = v;
+ const b: u64 = v;
+ const c: u64 = a;
+ var w: u64 = 0x1234567812345678;
+ const d: u10 = @truncate(w);
+ const e: u60 = d;
+ try expectEqual(@as(u32, 234), a);
+ try expectEqual(@as(u64, 234), b);
+ try expectEqual(@as(u64, 234), c);
+ try expectEqual(@as(u21, 0x278), d);
+ try expectEqual(@as(u60, 0x278), e);
+ }
+ {
+ var v: u7 = 11;
+ const a: u32 = v;
+ const b: u64 = v;
+ const c: u64 = a;
+ var w: u64 = 0x1234567812345678;
+ const d: u7 = @truncate(w);
+ const e: u60 = d;
+ try expectEqual(@as(u32, 11), a);
+ try expectEqual(@as(u64, 11), b);
+ try expectEqual(@as(u64, 11), c);
+ try expectEqual(@as(u21, 0x78), d);
+ try expectEqual(@as(u60, 0x78), e);
+ }
+
+ {
+ var v: i21 = -6417;
+ const a: i32 = v;
+ const b: i64 = v;
+ const c: i64 = a;
+ var w: i64 = -12345;
+ const d: i21 = @intCast(w);
+ const e: i60 = d;
+ try expectEqual(@as(i32, -6417), a);
+ try expectEqual(@as(i64, -6417), b);
+ try expectEqual(@as(i64, -6417), c);
+ try expectEqual(@as(i21, -12345), d);
+ try expectEqual(@as(i60, -12345), e);
+ }
+
+ {
+ var v: i10 = -234;
+ const a: i32 = v;
+ const b: i64 = v;
+ const c: i64 = a;
+ var w: i64 = -456;
+ const d: i10 = @intCast(w);
+ const e: i60 = d;
+ try expectEqual(@as(i32, -234), a);
+ try expectEqual(@as(i64, -234), b);
+ try expectEqual(@as(i64, -234), c);
+ try expectEqual(@as(i10, -456), d);
+ try expectEqual(@as(i60, -456), e);
+ }
+ {
+ var v: i7 = -11;
+ const a: i32 = v;
+ const b: i64 = v;
+ const c: i64 = a;
+ var w: i64 = -42;
+ const d: i7 = @intCast(w);
+ const e: i60 = d;
+ try expectEqual(@as(i32, -11), a);
+ try expectEqual(@as(i64, -11), b);
+ try expectEqual(@as(i64, -11), c);
+ try expectEqual(@as(i7, -42), d);
+ try expectEqual(@as(i60, -42), e);
+ }
+}
+
+const Piece = packed struct {
+ color: Color,
+ type: Type,
+
+ const Type = enum { KING, QUEEN, BISHOP, KNIGHT, ROOK, PAWN };
+ const Color = enum { WHITE, BLACK };
+
+ fn charToPiece(c: u8) !@This() {
+ return .{
+ .type = try charToPieceType(c),
+ .color = if (std.ascii.isUpper(c)) Color.WHITE else Color.BLACK,
+ };
+ }
+
+ fn charToPieceType(c: u8) !Type {
+ return switch (std.ascii.toLower(c)) {
+ 'p' => .PAWN,
+ 'k' => .KING,
+ 'q' => .QUEEN,
+ 'b' => .BISHOP,
+ 'n' => .KNIGHT,
+ 'r' => .ROOK,
+ else => error.UnexpectedCharError,
+ };
+ }
+};
+
+test "load non byte-sized optional value" {
+ // Originally reported at https://github.com/ziglang/zig/issues/14200
+ // note: this bug is triggered by the == operator, expectEqual will hide it
+ var opt: ?Piece = try Piece.charToPiece('p');
+ try expect(opt.?.type == .PAWN);
+ try expect(opt.?.color == .BLACK);
+
+ var p: Piece = undefined;
+ @as(*u8, @ptrCast(&p)).* = 0b11111011;
+ try expect(p.type == .PAWN);
+ try expect(p.color == .BLACK);
+}
+
+test "load non byte-sized value in struct" {
+ if (builtin.cpu.arch.endian() != .Little) return error.SkipZigTest; // packed struct TODO
+
+ // note: this bug is triggered by the == operator, expectEqual will hide it
+ // using ptrCast not to depend on unitialised memory state
+
+ var struct0: struct {
+ p: Piece,
+ int: u8,
+ } = undefined;
+ @as(*u8, @ptrCast(&struct0.p)).* = 0b11111011;
+ try expect(struct0.p.type == .PAWN);
+ try expect(struct0.p.color == .BLACK);
+
+ var struct1: packed struct {
+ p0: Piece,
+ p1: Piece,
+ pad: u1,
+ p2: Piece,
+ } = undefined;
+ @as(*u8, @ptrCast(&struct1.p0)).* = 0b11111011;
+ struct1.p1 = try Piece.charToPiece('p');
+ struct1.p2 = try Piece.charToPiece('p');
+ try expect(struct1.p0.type == .PAWN);
+ try expect(struct1.p0.color == .BLACK);
+ try expect(struct1.p1.type == .PAWN);
+ try expect(struct1.p1.color == .BLACK);
+ try expect(struct1.p2.type == .PAWN);
+ try expect(struct1.p2.color == .BLACK);
+}
+
+test "load non byte-sized value in union" {
+ if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
+ if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
+ if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest;
+ if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
+ if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
+ if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
+
+ // note: this bug is triggered by the == operator, expectEqual will hide it
+ // using ptrCast not to depend on unitialised memory state
+
+ var union0: packed union {
+ p: Piece,
+ int: u8,
+ } = .{ .int = 0 };
+ union0.int = 0b11111011;
+ try expect(union0.p.type == .PAWN);
+ try expect(union0.p.color == .BLACK);
+
+ var union1: union {
+ p: Piece,
+ int: u8,
+ } = .{ .p = .{ .color = .WHITE, .type = .KING } };
+ @as(*u8, @ptrCast(&union1.p)).* = 0b11111011;
+ try expect(union1.p.type == .PAWN);
+ try expect(union1.p.color == .BLACK);
+
+ var pieces: [3]Piece = undefined;
+ @as(*u8, @ptrCast(&pieces[1])).* = 0b11111011;
+ try expect(pieces[1].type == .PAWN);
+ try expect(pieces[1].color == .BLACK);
+}
diff --git a/test/behavior/packed-struct.zig b/test/behavior/packed-struct.zig
@@ -991,7 +991,7 @@ test "bitcast back and forth" {
test "field access of packed struct smaller than its abi size inside struct initialized with rls" {
// Originally reported at https://github.com/ziglang/zig/issues/14200
- if (builtin.zig_backend == .stage2_llvm and builtin.cpu.arch == .arm) return error.SkipZigTest;
+
const S = struct {
ps: packed struct { x: i2, y: i2 },
@@ -1036,3 +1036,32 @@ test "modify nested packed struct aligned field" {
try std.testing.expectEqual(@as(u8, 1), opts.pretty_print.indent);
try std.testing.expect(!opts.baz);
}
+
+test "assigning packed struct inside another packed struct" {
+ // Originally reported at https://github.com/ziglang/zig/issues/9674
+
+ const S = struct {
+ const Inner = packed struct {
+ bits: u3,
+ more_bits: u6,
+ };
+
+ const Outer = packed struct {
+ padding: u5,
+ inner: Inner,
+ };
+ fn t(inner: Inner) void {
+ r.inner = inner;
+ }
+
+ var mem: Outer = undefined;
+ var r: *volatile Outer = &mem;
+ };
+
+ const val = S.Inner{ .bits = 1, .more_bits = 11 };
+ S.mem.padding = 0;
+ S.t(val);
+
+ try expectEqual(val, S.mem.inner);
+ try expect(S.mem.padding == 0);
+}
diff --git a/test/behavior/packed-union.zig b/test/behavior/packed-union.zig
@@ -85,3 +85,31 @@ test "flags in packed union at offset" {
try expectEqual(false, test_bits.adv_flags.adv.flags.enable_1);
try expectEqual(false, test_bits.adv_flags.adv.flags.enable_2);
}
+
+test "packed union in packed struct" {
+ // Originally reported at https://github.com/ziglang/zig/issues/16581
+
+ const ReadRequest = packed struct { key: i32 };
+ const RequestType = enum {
+ read,
+ insert,
+ };
+ const RequestUnion = packed union {
+ read: ReadRequest,
+ };
+
+ const Request = packed struct {
+ active_type: RequestType,
+ request: RequestUnion,
+ const Self = @This();
+
+ fn init(read: ReadRequest) Self {
+ return .{
+ .active_type = .read,
+ .request = RequestUnion{ .read = read },
+ };
+ }
+ };
+
+ try std.testing.expectEqual(RequestType.read, Request.init(.{ .key = 3 }).active_type);
+}
