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stage2 regalloc: Fix bug where regs were not marked as allocated

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joachimschmidt557 2022-01-28 20:40:36 +01:00 committed by Andrew Kelley
parent d7deffee8d
commit 1a324a8ad6
1 changed files with 44 additions and 14 deletions
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58
src/register_manager.zig
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@ -17,6 +17,10 @@ pub fn RegisterManager(
comptime Register: type,
comptime callee_preserved_regs: []const Register,
) type {
// architectures which do not have a concept of registers should
// refrain from using RegisterManager
assert(callee_preserved_regs.len > 0); // see note above
return struct {
/// Tracks the AIR instruction allocated to every register or
/// `null` if no instruction is allocated to a register
@ -45,17 +49,20 @@ pub fn RegisterManager(
}
fn getRegisterMask(reg: Register) ?FreeRegInt {
if (FreeRegInt == u0) return null;
const index = reg.allocIndex() orelse return null;
const shift = @intCast(ShiftInt, index);
const mask = @as(FreeRegInt, 1) << shift;
return mask;
}
fn markRegAllocated(self: *Self, reg: Register) void {
const mask = getRegisterMask(reg) orelse return;
self.allocated_registers |= mask;
}
fn markRegUsed(self: *Self, reg: Register) void {
const mask = getRegisterMask(reg) orelse return;
self.free_registers &= ~mask;
self.allocated_registers |= mask;
}
fn markRegFree(self: *Self, reg: Register) void {
@ -120,7 +127,6 @@ pub fn RegisterManager(
insts: [count]?Air.Inst.Index,
exceptions: []const Register,
) ?[count]Register {
comptime if (callee_preserved_regs.len == 0) return null;
comptime assert(count > 0 and count <= callee_preserved_regs.len);
assert(count + exceptions.len <= callee_preserved_regs.len);
@ -138,19 +144,20 @@ pub fn RegisterManager(
i += 1;
}
}
assert(i == count);
if (i == count) {
for (regs) |reg, j| {
if (insts[j]) |inst| {
// Track the register
const index = reg.allocIndex().?; // allocIndex() on a callee-preserved reg should never return null
self.registers[index] = inst;
self.markRegUsed(reg);
}
for (regs) |reg, j| {
self.markRegAllocated(reg);
if (insts[j]) |inst| {
// Track the register
const index = reg.allocIndex().?; // allocIndex() on a callee-preserved reg should never return null
self.registers[index] = inst;
self.markRegUsed(reg);
}
}
return regs;
} else return null;
return regs;
}
/// Allocates a register and optionally tracks it with a
@ -188,8 +195,9 @@ pub fn RegisterManager(
if (i >= count) break;
if (mem.indexOfScalar(Register, exceptions, reg) != null) continue;
if (self.isRegFrozen(reg)) continue;
regs[i] = reg;
regs[i] = reg;
self.markRegAllocated(reg);
const index = reg.allocIndex().?; // allocIndex() on a callee-preserved reg should never return null
if (insts[i]) |inst| {
// Track the register
@ -233,6 +241,7 @@ pub fn RegisterManager(
/// register.
pub fn getReg(self: *Self, reg: Register, inst: ?Air.Inst.Index) !void {
const index = reg.allocIndex() orelse return;
self.markRegAllocated(reg);
if (inst) |tracked_inst|
if (!self.isRegFree(reg)) {
@ -260,6 +269,7 @@ pub fn RegisterManager(
/// spilling is necessary.
pub fn getRegAssumeFree(self: *Self, reg: Register, inst: Air.Inst.Index) void {
const index = reg.allocIndex() orelse return;
self.markRegAllocated(reg);
assert(self.registers[index] == null);
self.registers[index] = inst;
@ -424,6 +434,11 @@ test "tryAllocRegs" {
try expectEqual([_]MockRegister2{ .r0, .r1, .r2 }, function.register_manager.tryAllocRegs(3, .{ null, null, null }, &.{}).?);
try expect(function.register_manager.isRegAllocated(.r0));
try expect(function.register_manager.isRegAllocated(.r1));
try expect(function.register_manager.isRegAllocated(.r2));
try expect(!function.register_manager.isRegAllocated(.r3));
// Exceptions
//
// TODO deprecated, remove test once no backend uses exceptions
@ -444,6 +459,11 @@ test "tryAllocRegs" {
try expectEqual([_]MockRegister2{ .r0, .r2, .r3 }, function.register_manager.tryAllocRegs(3, .{ null, null, null }, &.{}).?);
}
try expect(!function.register_manager.frozenRegsExist());
try expect(function.register_manager.isRegAllocated(.r0));
try expect(function.register_manager.isRegAllocated(.r1));
try expect(function.register_manager.isRegAllocated(.r2));
try expect(function.register_manager.isRegAllocated(.r3));
}
test "allocRegs" {
@ -462,6 +482,11 @@ test "allocRegs" {
mock_instruction,
}, &.{}));
try expect(function.register_manager.isRegAllocated(.r0));
try expect(function.register_manager.isRegAllocated(.r1));
try expect(function.register_manager.isRegAllocated(.r2));
try expect(!function.register_manager.isRegAllocated(.r3));
// Exceptions
//
// TODO deprecated, remove test once no backend uses exceptions
@ -480,6 +505,11 @@ test "allocRegs" {
try expectEqual([_]MockRegister2{ .r0, .r2, .r3 }, try function.register_manager.allocRegs(3, .{ null, null, null }, &.{}));
}
try expect(!function.register_manager.frozenRegsExist());
try expect(function.register_manager.isRegAllocated(.r0));
try expect(function.register_manager.isRegAllocated(.r1));
try expect(function.register_manager.isRegAllocated(.r2));
try expect(function.register_manager.isRegAllocated(.r3));
}
test "getReg" {