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C backend: fix memset for structs and arrays

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This commit is contained in:
Andrew Kelley 2023-04-26 17:53:25 -07:00
parent 9295355985
commit 36df2a83fc
1 changed files with 90 additions and 29 deletions
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119
src/codegen/c.zig
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@ -4419,51 +4419,94 @@ fn airBitcast(f: *Function, inst: Air.Inst.Index) !CValue {
const dest_ty = f.air.typeOfIndex(inst);
const operand = try f.resolveInst(ty_op.operand);
try reap(f, inst, &.{ty_op.operand});
const operand_ty = f.air.typeOf(ty_op.operand);
const bitcasted = try bitcast(f, dest_ty, operand, operand_ty);
try reap(f, inst, &.{ty_op.operand});
return bitcasted.move(f, inst, dest_ty);
}
const LocalResult = struct {
c_value: CValue,
need_free: bool,
fn move(lr: LocalResult, f: *Function, inst: Air.Inst.Index, dest_ty: Type) !CValue {
if (lr.need_free) {
// Move the freshly allocated local to be owned by this instruction,
// by returning it here instead of freeing it.
return lr.c_value;
}
const local = try f.allocLocal(inst, dest_ty);
try lr.free(f);
const writer = f.object.writer();
try f.writeCValue(writer, local, .Other);
if (dest_ty.isAbiInt()) {
try writer.writeAll(" = ");
} else {
try writer.writeAll(" = (");
try f.renderType(writer, dest_ty);
try writer.writeByte(')');
}
try f.writeCValue(writer, lr.c_value, .Initializer);
try writer.writeAll(";\n");
return local;
}
fn free(lr: LocalResult, f: *Function) !void {
if (lr.need_free) {
try freeLocal(f, 0, lr.c_value.new_local, 0);
}
}
};
fn bitcast(f: *Function, dest_ty: Type, operand: CValue, operand_ty: Type) !LocalResult {
const target = f.object.dg.module.getTarget();
const writer = f.object.writer();
const local = try f.allocLocal(inst, dest_ty);
// If the assignment looks like 'x = x', we don't need it
const can_elide = operand == .local and operand.local == local.new_local;
if (operand_ty.isAbiInt() and dest_ty.isAbiInt()) {
if (can_elide) return local;
const src_info = dest_ty.intInfo(target);
const dest_info = operand_ty.intInfo(target);
if (src_info.signedness == dest_info.signedness and
src_info.bits == dest_info.bits)
{
try f.writeCValue(writer, local, .Other);
try writer.writeAll(" = ");
try f.writeCValue(writer, operand, .Initializer);
try writer.writeAll(";\n");
return local;
return .{
.c_value = operand,
.need_free = false,
};
}
}
if (dest_ty.isPtrAtRuntime() and operand_ty.isPtrAtRuntime()) {
if (can_elide) return local;
const local = try f.allocLocal(0, dest_ty);
try f.writeCValue(writer, local, .Other);
try writer.writeAll(" = (");
try f.renderType(writer, dest_ty);
try writer.writeByte(')');
try f.writeCValue(writer, operand, .Other);
try writer.writeAll(";\n");
return local;
return .{
.c_value = local,
.need_free = true,
};
}
const operand_lval = if (operand == .constant) blk: {
const operand_local = try f.allocLocal(inst, operand_ty);
const operand_local = try f.allocLocal(0, operand_ty);
try f.writeCValue(writer, operand_local, .Other);
try writer.writeAll(" = ");
if (operand_ty.isAbiInt()) {
try writer.writeAll(" = ");
} else {
try writer.writeAll(" = (");
try f.renderType(writer, operand_ty);
try writer.writeByte(')');
}
try f.writeCValue(writer, operand, .Initializer);
try writer.writeAll(";\n");
break :blk operand_local;
} else operand;
const local = try f.allocLocal(0, dest_ty);
try writer.writeAll("memcpy(&");
try f.writeCValue(writer, local, .Other);
try writer.writeAll(", &");
@ -4528,10 +4571,13 @@ fn airBitcast(f: *Function, inst: Air.Inst.Index) !CValue {
}
if (operand == .constant) {
try freeLocal(f, inst, operand_lval.new_local, 0);
try freeLocal(f, 0, operand_lval.new_local, 0);
}
return local;
return .{
.c_value = local,
.need_free = true,
};
}
fn airTrap(writer: anytype) !CValue {
@ -6288,15 +6334,27 @@ fn airMemset(f: *Function, inst: Air.Inst.Index, safety: bool) !CValue {
}
try writer.writeAll("; ++");
try f.writeCValue(writer, index, .Other);
try writer.writeAll(") ((");
try f.renderType(writer, elem_ptr_ty);
try writer.writeByte(')');
try writeSliceOrPtr(f, writer, dest_slice, dest_ty);
try writer.writeAll(")[");
try f.writeCValue(writer, index, .Other);
try writer.writeAll("] = ");
try f.writeCValue(writer, value, .FunctionArgument);
try writer.writeAll(";\n");
try writer.writeAll(") ");
if (lowersToArray(elem_ty, target)) {
// Arrays are not assignable, so we use memcpy here.
try writer.writeAll("memcpy(");
try writeSliceOrPtr(f, writer, dest_slice, dest_ty);
try writer.writeAll("[");
try f.writeCValue(writer, index, .Other);
try writer.writeAll("], ");
try f.writeCValue(writer, value, .FunctionArgument);
try writer.print(", {d});\n", .{elem_abi_size});
} else {
try writer.writeAll("((");
try f.renderType(writer, elem_ptr_ty);
try writer.writeByte(')');
try writeSliceOrPtr(f, writer, dest_slice, dest_ty);
try writer.writeAll(")[");
try f.writeCValue(writer, index, .Other);
try writer.writeAll("] = ");
try f.writeCValue(writer, value, .FunctionArgument);
try writer.writeAll(";\n");
}
try reap(f, inst, &.{ bin_op.lhs, bin_op.rhs });
try freeLocal(f, inst, index.new_local, 0);
@ -6304,12 +6362,14 @@ fn airMemset(f: *Function, inst: Air.Inst.Index, safety: bool) !CValue {
return .none;
}
const bitcasted = try bitcast(f, Type.u8, value, elem_ty);
try writer.writeAll("memset(");
switch (dest_ty.ptrSize()) {
.Slice => {
try f.writeCValueMember(writer, dest_slice, .{ .identifier = "ptr" });
try writer.writeAll(", ");
try f.writeCValue(writer, value, .FunctionArgument);
try f.writeCValue(writer, bitcasted.c_value, .FunctionArgument);
try writer.writeAll(", ");
try f.writeCValueMember(writer, dest_slice, .{ .identifier = "len" });
try writer.writeAll(");\n");
@ -6320,11 +6380,12 @@ fn airMemset(f: *Function, inst: Air.Inst.Index, safety: bool) !CValue {
try f.writeCValue(writer, dest_slice, .FunctionArgument);
try writer.writeAll(", ");
try f.writeCValue(writer, value, .FunctionArgument);
try f.writeCValue(writer, bitcasted.c_value, .FunctionArgument);
try writer.print(", {d});\n", .{len});
},
.Many, .C => unreachable,
}
try bitcasted.free(f);
try reap(f, inst, &.{ bin_op.lhs, bin_op.rhs });
return .none;
}