diff options
Diffstat (limited to 'src/codegen.zig')
| -rw-r--r-- | src/codegen.zig | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/src/codegen.zig b/src/codegen.zig index d2b5d2a..f186304 100644 --- a/src/codegen.zig +++ b/src/codegen.zig @@ -560,11 +560,16 @@ const Context = struct { try self.instructions.append(inst); } - fn maybeFreeSources(self: *Context) !void { - const index = self.current_instruction_index.?; - if (self.block.?.vreg_last_use.get(index)) |last_used_here| { - for (last_used_here.items) |vreg| { - self.register_allocator.free(vreg); + /// Frees all virtual registers who's last use is the current `compile.Instr` or earlier. This + /// must be called after the current compile.Instr's sources have been retrieved, since this + /// will deallocate them, and after allocating auxiliary registers since otherwise they may + /// collide with the sources. Should be called before allocating results to allow for more + /// register re-use. + fn freeUnusedVRegs(self: *Context) !void { + var it = self.register_allocator.allocated.keyIterator(); + while (it.next()) |vreg| { + if (self.block.?.vreg_last_use.get(vreg.*).? <= self.current_instruction_index.?) { + self.register_allocator.free(vreg.*); } } } @@ -595,6 +600,7 @@ const Context = struct { } fn genConstant(self: *Context, constant: compile.Instr.Constant) !void { + try self.freeUnusedVRegs(); const reg = try self.register_allocator.allocate(constant.dest); try self.genConstantInner(reg, constant.value); } @@ -602,7 +608,7 @@ const Context = struct { fn genBinOp(self: *Context, bin_op: compile.Instr.BinOp) !void { const lhs = self.register_allocator.get(bin_op.lhs); const rhs = self.register_allocator.get(bin_op.rhs); - try self.maybeFreeSources(); + try self.freeUnusedVRegs(); const reg = try self.register_allocator.allocate(bin_op.dest); switch (bin_op.op) { .add => try self.emit(.add(reg, lhs, rhs)), @@ -621,7 +627,7 @@ const Context = struct { defer self.register_allocator.freeAux(digit); const count = try self.register_allocator.allocate(call.dest); - try self.maybeFreeSources(); + try self.freeUnusedVRegs(); try self.emit(.addi(digit, .zero, '\n')); try self.emit(.addi(.sp, .sp, -1)); @@ -648,7 +654,7 @@ const Context = struct { try self.emit(.addi(count, count, -1)); }, .read_int => { - try self.maybeFreeSources(); + try self.freeUnusedVRegs(); const result = try self.register_allocator.allocate(call.dest); const ptr = try self.register_allocator.allocateAux(); @@ -689,10 +695,6 @@ const Context = struct { } } - fn genDiscard(self: *Context, _: compile.Instr.Discard) !void { - try self.maybeFreeSources(); - } - fn codegenInstr(self: *Context, instr: compile.Instr) !void { switch (instr.type) { inline else => |ty| { |