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Add tests, fix locals that are created in blocks like loops, and handle all breaks correctly

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This commit is contained in:
Luuk de Gram
2021-01-26 19:47:15 +01:00
parent a0d81caec9
commit cc46c1b902
3 changed files with 147 additions and 42 deletions
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88
src/codegen/wasm.zig
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@@ -163,11 +163,8 @@ pub const Context = struct {
try self.genFunctype();
const writer = self.code.writer();
// Reserve space to write the size after generating the code
try self.code.resize(5);
// offset into 'code' section where we will put our locals count
var local_offset = self.code.items.len;
// Reserve space to write the size after generating the code as well as space for locals count
try self.code.resize(10);
// Write instructions
// TODO: check for and handle death of instructions
@@ -177,10 +174,10 @@ pub const Context = struct {
// finally, write our local types at the 'offset' position
{
var totals_buffer: [5]u8 = undefined;
leb.writeUnsignedFixed(5, totals_buffer[0..5], @intCast(u32, self.locals.items.len));
try self.code.insertSlice(local_offset, &totals_buffer);
local_offset += 5;
leb.writeUnsignedFixed(5, self.code.items[5..10], @intCast(u32, self.locals.items.len));
// offset into 'code' section where we will put our locals types
var local_offset: usize = 10;
// emit the actual locals amount
for (self.locals.items) |local| {
@@ -285,8 +282,7 @@ pub const Context = struct {
}
fn genLoad(self: *Context, inst: *Inst.UnOp) InnerError!WValue {
const operand = self.resolveInst(inst.operand);
return operand;
return self.resolveInst(inst.operand);
}
fn genArg(self: *Context, inst: *Inst.Arg) InnerError!WValue {
@@ -351,35 +347,49 @@ pub const Context = struct {
fn genBlock(self: *Context, block: *Inst.Block) InnerError!WValue {
const block_ty = try self.genBlockType(block.base.src, block.base.ty);
try self.startBlock(.block, block_ty, null);
block.codegen = .{
// we don't use relocs, so using `relocs` is illegal behaviour.
.relocs = undefined,
// Here we set the current block idx, so conditions know the depth to jump
// to when breaking out. This will be set to .none when it is found again within
// the same block
// Here we set the current block idx, so breaks know the depth to jump
// to when breaking out.
.mcv = @bitCast(AnyMCValue, WValue{ .block_idx = self.block_depth }),
};
self.block_depth += 1;
try self.code.append(wasm.opcode(.block));
try self.code.append(block_ty);
try self.genBody(block.body);
try self.code.append(wasm.opcode(.end));
try self.endBlock();
self.block_depth -= 1;
return .none;
}
/// appends a new wasm block to the code section and increases the `block_depth` by 1
fn startBlock(self: *Context, block_type: wasm.Opcode, valtype: u8, with_offset: ?usize) !void {
self.block_depth += 1;
if (with_offset) |offset| {
try self.code.insert(offset, wasm.opcode(block_type));
try self.code.insert(offset + 1, valtype);
} else {
try self.code.append(wasm.opcode(block_type));
try self.code.append(valtype);
}
}
/// Ends the current wasm block and decreases the `block_depth` by 1
fn endBlock(self: *Context) !void {
try self.code.append(wasm.opcode(.end));
self.block_depth -= 1;
}
fn genLoop(self: *Context, loop: *Inst.Loop) InnerError!WValue {
const loop_ty = try self.genBlockType(loop.base.src, loop.base.ty);
try self.code.append(wasm.opcode(.loop));
try self.code.append(loop_ty);
self.block_depth += 1;
try self.startBlock(.loop, loop_ty, null);
try self.genBody(loop.body);
self.block_depth -= 1;
try self.code.append(wasm.opcode(.end));
// breaking to the index of a loop block will continue the loop instead
try self.code.append(wasm.opcode(.br));
try leb.writeULEB128(self.code.writer(), @as(u32, 0));
try self.endBlock();
return .none;
}
@@ -388,23 +398,22 @@ pub const Context = struct {
const condition = self.resolveInst(condbr.condition);
const writer = self.code.writer();
// TODO: Handle death instructions for then and else body
// insert blocks at the position of `offset` so
// the condition can jump to it
const offset = condition.code_offset;
try self.code.insert(offset, wasm.opcode(.block));
try self.code.insert(offset, try self.genBlockType(condbr.base.src, condbr.base.ty));
const block_ty = try self.genBlockType(condbr.base.src, condbr.base.ty);
try self.startBlock(.block, block_ty, offset);
// we inserted the block in front of the condition
// so now check if condition matches. If not, break outside this block
// and continue with the regular codepath
// and continue with the then codepath
try writer.writeByte(wasm.opcode(.br_if));
try leb.writeULEB128(writer, @as(u32, 0));
// else body in case condition does not match
try self.genBody(condbr.else_body);
// finally, tell wasm we have reached the end of the block we inserted above
try writer.writeByte(wasm.opcode(.end));
try self.endBlock();
// Outer block that matches the condition
try self.genBody(condbr.then_body);
@@ -417,7 +426,7 @@ pub const Context = struct {
// save offset, so potential conditions can insert blocks in front of
// the comparison that we can later jump back to
const offset = self.code.items.len - 1;
const offset = self.code.items.len;
const lhs = self.resolveInst(inst.lhs);
const rhs = self.resolveInst(inst.rhs);
@@ -492,17 +501,14 @@ pub const Context = struct {
try self.emitWValue(operand);
}
// if the block contains a block_idx, do a relative jump to it
// if `wvalue` was already 'consumed', simply break out of current block
// every block contains a `WValue` with its block index.
// We then determine how far we have to jump to it by substracting it from current block depth
const wvalue = @bitCast(WValue, br.block.codegen.mcv);
const idx: u32 = if (wvalue == .block_idx) blk: {
br.block.codegen.mcv = @bitCast(AnyMCValue, WValue{ .none = {} });
break :blk self.block_depth - wvalue.block_idx;
} else 0;
const idx: u32 = self.block_depth - wvalue.block_idx;
const writer = self.code.writer();
try writer.writeByte(wasm.opcode(.br));
try leb.writeULEB128(writer, idx);
return WValue.none;
return .none;
}
};