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no-copy semantics for switch expressions
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```zig
export fn entry() void {
    var c: i32 = 1234;
    var x = switch (c) {
        1 => u8(1),
        2...4 => u16(2),
        else => u32(3),
    };
}
```

```llvm
define void @entry() #2 !dbg !35 {
Entry:
  %c = alloca i32, align 4
  %x = alloca i32, align 4
  store i32 1234, i32* %c, align 4, !dbg !44
  call void @llvm.dbg.declare(metadata i32* %c, metadata !39, metadata !DIExpression()), !dbg !44
  %0 = load i32, i32* %c, align 4, !dbg !45
  %1 = icmp sge i32 %0, 2, !dbg !46
  %2 = icmp sle i32 %0, 4, !dbg !46
  %3 = and i1 %1, %2, !dbg !46
  br i1 %3, label %SwitchRangeYes, label %SwitchRangeNo, !dbg !46

SwitchRangeYes:                                   ; preds = %Entry
  br label %SwitchEnd, !dbg !45

SwitchElse:                                       ; preds = %SwitchRangeNo
  br label %SwitchEnd, !dbg !45

SwitchProng:                                      ; preds = %SwitchRangeNo
  br label %SwitchEnd, !dbg !45

SwitchEnd:                                        ; preds = %SwitchProng, %SwitchElse, %SwitchRangeYes
  %4 = phi i32 [ 2, %SwitchRangeYes ], [ 3, %SwitchElse ], [ 1, %SwitchProng ], !dbg !45
  store i32 %4, i32* %x, align 4, !dbg !45
  call void @llvm.dbg.declare(metadata i32* %x, metadata !42, metadata !DIExpression()), !dbg !47
  ret void, !dbg !48

SwitchRangeNo:                                    ; preds = %Entry
  switch i32 %0, label %SwitchElse [
    i32 1, label %SwitchProng
  ], !dbg !45
}
```
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@andrewrk
andrewrk committed Jun 4, 2019
1 parent 057b960 commit b19b1c1
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9 changes: 6 additions & 3 deletions BRANCH_TODO
View file
Original file line number Diff line number Diff line change
@@ -1,14 +1,17 @@
Scratch pad for stuff to do before merging master
=================================================

migrate ir_build_var_decl_src to use ir_build_alloca_src and explicitly initialize

* switch expression
* if bool - do we need to call lval wrap or just expr wrap?
* hook up peer result locs to if optional and if err
* hook up peer result locs to while bool, while optional, and while err
* hook up peer result locs to for
* hook up peer result locs to catch
* struct initializations
* function call parameters
* bitCast

look at all the ir_gen_node ir_gen_node_extra calls and make sure result locations are properly propagated
return ir_gen_comptime(irb, scope, node, lval);

migrate all the alloca_list to alloca_gen_list

Expand Down
85 changes: 65 additions & 20 deletions src/ir.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6510,7 +6510,7 @@ static bool ir_gen_switch_prong_expr(IrBuilder *irb, Scope *scope, AstNode *swit
IrBasicBlock *end_block, IrInstruction *is_comptime, IrInstruction *var_is_comptime,
IrInstruction *target_value_ptr, IrInstruction **prong_values, size_t prong_values_len,
ZigList<IrBasicBlock *> *incoming_blocks, ZigList<IrInstruction *> *incoming_values,
IrInstructionSwitchElseVar **out_switch_else_var)
IrInstructionSwitchElseVar **out_switch_else_var, LVal lval, ResultLoc *result_loc)
{
assert(switch_node->type == NodeTypeSwitchExpr);
assert(prong_node->type == NodeTypeSwitchProng);
Expand All @@ -6528,27 +6528,27 @@ static bool ir_gen_switch_prong_expr(IrBuilder *irb, Scope *scope, AstNode *swit
ZigVar *var = ir_create_var(irb, var_symbol_node, scope,
var_name, is_const, is_const, is_shadowable, var_is_comptime);
child_scope = var->child_scope;
IrInstruction *var_value;
IrInstruction *var_ptr;
if (out_switch_else_var != nullptr) {
IrInstructionSwitchElseVar *switch_else_var = ir_build_switch_else_var(irb, scope, var_symbol_node,
target_value_ptr);
*out_switch_else_var = switch_else_var;
IrInstruction *var_ptr_value = &switch_else_var->base;
var_value = var_is_ptr ? var_ptr_value : ir_build_load_ptr(irb, scope, var_symbol_node, var_ptr_value);
IrInstruction *payload_ptr = &switch_else_var->base;
var_ptr = var_is_ptr ? ir_build_ref(irb, scope, var_symbol_node, payload_ptr, true, false) : payload_ptr;
} else if (prong_values != nullptr) {
IrInstruction *var_ptr_value = ir_build_switch_var(irb, scope, var_symbol_node, target_value_ptr,
IrInstruction *payload_ptr = ir_build_switch_var(irb, scope, var_symbol_node, target_value_ptr,
prong_values, prong_values_len);
var_value = var_is_ptr ? var_ptr_value : ir_build_load_ptr(irb, scope, var_symbol_node, var_ptr_value);
var_ptr = var_is_ptr ? ir_build_ref(irb, scope, var_symbol_node, payload_ptr, true, false) : payload_ptr;
} else {
var_value = var_is_ptr ? target_value_ptr : ir_build_load_ptr(irb, scope, var_symbol_node,
target_value_ptr);
var_ptr = var_is_ptr ?
ir_build_ref(irb, scope, var_symbol_node, target_value_ptr, true, false) : target_value_ptr;
}
ir_build_var_decl_src(irb, scope, var_symbol_node, var, nullptr, var_value);
ir_build_var_decl_src(irb, scope, var_symbol_node, var, nullptr, var_ptr);
} else {
child_scope = scope;
}

IrInstruction *expr_result = ir_gen_node(irb, expr_node, child_scope);
IrInstruction *expr_result = ir_gen_node_extra(irb, expr_node, child_scope, lval, result_loc);
if (expr_result == irb->codegen->invalid_instruction)
return false;
if (!instr_is_unreachable(expr_result))
Expand All @@ -6558,7 +6558,15 @@ target_value_ptr);
return true;
}

static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *node) {
static void next_peer_block(ZigList<ResultLocPeer> *list, IrBasicBlock *next_bb) {
if (list->length >= 2) {
list->at(list->length - 2).next_bb = next_bb;
}
}

static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *node, LVal lval,
ResultLoc *result_loc)
{
assert(node->type == NodeTypeSwitchExpr);

AstNode *target_node = node->data.switch_expr.expr;
Expand Down Expand Up @@ -6589,6 +6597,12 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *

IrInstructionSwitchElseVar *switch_else_var = nullptr;

ResultLocPeerParent *peer_parent = allocate<ResultLocPeerParent>(1);
peer_parent->base.id = ResultLocIdPeerParent;
peer_parent->parent = result_loc;

ZigList<ResultLocPeer> peer_result_locs = {};

// First do the else and the ranges
Scope *subexpr_scope = create_runtime_scope(irb->codegen, node, scope, is_comptime);
Scope *comptime_scope = create_comptime_scope(irb->codegen, node, scope);
Expand All @@ -6597,6 +6611,9 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *
AstNode *prong_node = node->data.switch_expr.prongs.at(prong_i);
size_t prong_item_count = prong_node->data.switch_prong.items.length;
if (prong_item_count == 0) {
ResultLocPeer *this_peer_result_loc = peer_result_locs.add_one();
this_peer_result_loc->base.id = ResultLocIdPeer;
this_peer_result_loc->parent = peer_parent;
if (else_prong) {
ErrorMsg *msg = add_node_error(irb->codegen, prong_node,
buf_sprintf("multiple else prongs in switch expression"));
Expand All @@ -6607,15 +6624,20 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *
else_prong = prong_node;

IrBasicBlock *prev_block = irb->current_basic_block;
next_peer_block(&peer_result_locs, else_block);
ir_set_cursor_at_end_and_append_block(irb, else_block);
if (!ir_gen_switch_prong_expr(irb, subexpr_scope, node, prong_node, end_block,
is_comptime, var_is_comptime, target_value_ptr, nullptr, 0, &incoming_blocks, &incoming_values,
&switch_else_var))
&switch_else_var, lval, &this_peer_result_loc->base))
{
return irb->codegen->invalid_instruction;
}
ir_set_cursor_at_end(irb, prev_block);
} else if (prong_node->data.switch_prong.any_items_are_range) {
ResultLocPeer *this_peer_result_loc = peer_result_locs.add_one();
this_peer_result_loc->base.id = ResultLocIdPeer;
this_peer_result_loc->parent = peer_parent;

IrInstruction *ok_bit = nullptr;
AstNode *last_item_node = nullptr;
for (size_t item_i = 0; item_i < prong_item_count; item_i += 1) {
Expand Down Expand Up @@ -6675,10 +6697,11 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *
ir_mark_gen(ir_build_cond_br(irb, scope, last_item_node, ok_bit, range_block_yes,
range_block_no, is_comptime));

next_peer_block(&peer_result_locs, range_block_yes);
ir_set_cursor_at_end_and_append_block(irb, range_block_yes);
if (!ir_gen_switch_prong_expr(irb, subexpr_scope, node, prong_node, end_block,
is_comptime, var_is_comptime, target_value_ptr, nullptr, 0,
&incoming_blocks, &incoming_values, nullptr))
&incoming_blocks, &incoming_values, nullptr, lval, &this_peer_result_loc->base))
{
return irb->codegen->invalid_instruction;
}
Expand All @@ -6696,6 +6719,10 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *
if (prong_node->data.switch_prong.any_items_are_range)
continue;

ResultLocPeer *this_peer_result_loc = peer_result_locs.add_one();
this_peer_result_loc->base.id = ResultLocIdPeer;
this_peer_result_loc->parent = peer_parent;

IrBasicBlock *prong_block = ir_create_basic_block(irb, scope, "SwitchProng");
IrInstruction **items = allocate<IrInstruction *>(prong_item_count);

Expand All @@ -6719,10 +6746,11 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *
}

IrBasicBlock *prev_block = irb->current_basic_block;
next_peer_block(&peer_result_locs, prong_block);
ir_set_cursor_at_end_and_append_block(irb, prong_block);
if (!ir_gen_switch_prong_expr(irb, subexpr_scope, node, prong_node, end_block,
is_comptime, var_is_comptime, target_value_ptr, items, prong_item_count,
&incoming_blocks, &incoming_values, nullptr))
&incoming_blocks, &incoming_values, nullptr, lval, &this_peer_result_loc->base))
{
return irb->codegen->invalid_instruction;
}
Expand All @@ -6731,31 +6759,48 @@ static IrInstruction *ir_gen_switch_expr(IrBuilder *irb, Scope *scope, AstNode *

}

IrInstruction *switch_prongs_void = ir_build_check_switch_prongs(irb, scope, node, target_value, check_ranges.items, check_ranges.length,
else_prong != nullptr);
IrInstruction *switch_prongs_void = ir_build_check_switch_prongs(irb, scope, node, target_value,
check_ranges.items, check_ranges.length, else_prong != nullptr);

IrInstruction *br_instruction;
if (cases.length == 0) {
ir_build_br(irb, scope, node, else_block, is_comptime);
br_instruction = ir_build_br(irb, scope, node, else_block, is_comptime);
} else {
IrInstructionSwitchBr *switch_br = ir_build_switch_br(irb, scope, node, target_value, else_block,
cases.length, cases.items, is_comptime, switch_prongs_void);
if (switch_else_var != nullptr) {
switch_else_var->switch_br = switch_br;
}
br_instruction = &switch_br->base;
}
for (size_t i = 0; i < peer_result_locs.length; i += 1) {
peer_result_locs.at(i).base.source_instruction = br_instruction;
}
peer_parent->base.source_instruction = br_instruction;
peer_parent->peer_count = peer_result_locs.length;
peer_parent->peers = peer_result_locs.items;

if (!else_prong) {
if (peer_result_locs.length != 0) {
peer_result_locs.last().next_bb = else_block;
}
ir_set_cursor_at_end_and_append_block(irb, else_block);
ir_build_unreachable(irb, scope, node);
} else {
if (peer_result_locs.length != 0) {
peer_result_locs.last().next_bb = end_block;
}
}

ir_set_cursor_at_end_and_append_block(irb, end_block);
assert(incoming_blocks.length == incoming_values.length);
IrInstruction *result_instruction;
if (incoming_blocks.length == 0) {
return ir_build_const_void(irb, scope, node);
result_instruction = ir_build_const_void(irb, scope, node);
} else {
return ir_build_phi(irb, scope, node, incoming_blocks.length, incoming_blocks.items, incoming_values.items);
result_instruction = ir_build_phi(irb, scope, node, incoming_blocks.length, incoming_blocks.items, incoming_values.items);
}
return ir_expr_wrap(irb, scope, result_instruction, result_loc);
}

static IrInstruction *ir_gen_comptime(IrBuilder *irb, Scope *parent_scope, AstNode *node, LVal lval) {
Expand Down Expand Up @@ -7828,7 +7873,7 @@ static IrInstruction *ir_gen_node_raw(IrBuilder *irb, AstNode *node, Scope *scop
case NodeTypeIfOptional:
return ir_lval_wrap(irb, scope, ir_gen_if_optional_expr(irb, scope, node), lval, result_loc);
case NodeTypeSwitchExpr:
return ir_lval_wrap(irb, scope, ir_gen_switch_expr(irb, scope, node), lval, result_loc);
return ir_gen_switch_expr(irb, scope, node, lval, result_loc);
case NodeTypeCompTime:
return ir_gen_comptime(irb, scope, node, lval);
case NodeTypeErrorType:
Expand Down

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