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Merge pull request #12177 from Vexu/packed-ptr

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stage2 llvm: fix handling of pointer fields in packed structs
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Andrew Kelley 2022-07-20 18:22:25 -04:00 committed by GitHub
commit c1f3aca602
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2 changed files with 31 additions and 1 deletions
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10
src/codegen/llvm.zig
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@ -5149,6 +5149,11 @@ pub const FuncGen = struct {
const same_size_int = self.context.intType(elem_bits);
const truncated_int = self.builder.buildTrunc(shifted_value, same_size_int, "");
return self.builder.buildBitCast(truncated_int, elem_llvm_ty, "");
} else if (field_ty.zigTypeTag() == .Pointer) {
const elem_bits = @intCast(c_uint, field_ty.bitSize(target));
const same_size_int = self.context.intType(elem_bits);
const truncated_int = self.builder.buildTrunc(shifted_value, same_size_int, "");
return self.builder.buildIntToPtr(truncated_int, elem_llvm_ty, "");
}
return self.builder.buildTrunc(shifted_value, elem_llvm_ty, "");
},
@ -7999,7 +8004,10 @@ pub const FuncGen = struct {
const non_int_val = try self.resolveInst(elem);
const ty_bit_size = @intCast(u16, field.ty.bitSize(target));
const small_int_ty = self.dg.context.intType(ty_bit_size);
const small_int_val = self.builder.buildBitCast(non_int_val, small_int_ty, "");
const small_int_val = if (field.ty.zigTypeTag() == .Pointer)
self.builder.buildPtrToInt(non_int_val, small_int_ty, "")
else
self.builder.buildBitCast(non_int_val, small_int_ty, "");
const shift_rhs = int_llvm_ty.constInt(running_bits, .False);
// If the field is as large as the entire packed struct, this
// zext would go from, e.g. i16 to i16. This is legal with

22
test/behavior/packed-struct.zig
View File

@ -413,3 +413,25 @@ test "byte-aligned field pointer offsets" {
try S.doTheTest();
comptime try S.doTheTest();
}
test "load pointer from packed struct" {
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
const A = struct {
index: u16,
};
const B = packed struct {
x: *A,
y: u32,
};
var a: A = .{ .index = 123 };
var b_list: []B = &.{.{ .x = &a, .y = 99 }};
for (b_list) |b| {
var i = b.x.index;
try expect(i == 123);
}
}