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x64: handle CF flags spilling in overflow calls

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Handle spilling of CF flags set with an overflow call.
Add saving stack offset to memory.
This commit is contained in:
Jakub Konka
2022-05-06 09:03:08 +02:00
parent df38dfa4d1
commit ac1aaec9c3
1 changed files with 34 additions and 6 deletions
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40
src/arch/x86_64/CodeGen.zig
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@@ -966,14 +966,16 @@ pub fn spillCompareFlagsIfOccupied(self: *Self) !void {
const mcv = self.getResolvedInstValue(inst_to_save);
assert(mcv.usesCompareFlags());
const new_mcv = try self.allocRegOrMem(inst_to_save, true);
const new_mcv = try self.allocRegOrMem(inst_to_save, !mcv.isRegister());
try self.setRegOrMem(self.air.typeOfIndex(inst_to_save), new_mcv, mcv);
log.debug("spilling {d} to mcv {any}", .{ inst_to_save, new_mcv });
const branch = &self.branch_stack.items[self.branch_stack.items.len - 1];
try branch.inst_table.put(self.gpa, inst_to_save, new_mcv);
self.compare_flags_inst = null;
// TODO consolidate with register manager and spillInstruction
// this call should really belong in the register manager!
if (mcv.isRegister()) self.register_manager.freeReg(mcv.asRegister().?);
}
}
@@ -1404,6 +1406,9 @@ fn airAddWithOverflow(self: *Self, inst: Air.Inst.Index) !void {
return self.fail("TODO implement add_with_overflow for Ints larger than 64bits", .{});
}
try self.spillCompareFlagsIfOccupied();
self.compare_flags_inst = inst;
const partial = try self.genBinMathOp(inst, bin_op.lhs, bin_op.rhs);
const result: MCValue = switch (int_info.signedness) {
.signed => .{ .register_overflow_signed = partial.register },
@@ -1433,6 +1438,9 @@ fn airSubWithOverflow(self: *Self, inst: Air.Inst.Index) !void {
return self.fail("TODO implement sub_with_overflow for Ints larger than 64bits", .{});
}
try self.spillCompareFlagsIfOccupied();
self.compare_flags_inst = inst;
const partial = try self.genSubOp(inst, bin_op.lhs, bin_op.rhs);
const result: MCValue = switch (int_info.signedness) {
.signed => .{ .register_overflow_signed = partial.register },
@@ -1456,9 +1464,6 @@ fn airMulWithOverflow(self: *Self, inst: Air.Inst.Index) !void {
switch (ty.zigTypeTag()) {
.Vector => return self.fail("TODO implement mul_with_overflow for Vector type", .{}),
.Int => {
try self.spillCompareFlagsIfOccupied();
self.compare_flags_inst = null;
const int_info = ty.intInfo(self.target.*);
if (int_info.bits > 64) {
@@ -1466,6 +1471,9 @@ fn airMulWithOverflow(self: *Self, inst: Air.Inst.Index) !void {
}
if (math.isPowerOfTwo(int_info.bits)) {
try self.spillCompareFlagsIfOccupied();
self.compare_flags_inst = inst;
// Spill .rax and .rdx upfront to ensure we don't spill the operands too late.
try self.register_manager.getReg(.rax, inst);
try self.register_manager.getReg(.rdx, null);
@@ -1487,6 +1495,9 @@ fn airMulWithOverflow(self: *Self, inst: Air.Inst.Index) !void {
break :result result;
}
try self.spillCompareFlagsIfOccupied();
self.compare_flags_inst = null;
const dst_reg: Register = dst_reg: {
switch (int_info.signedness) {
.signed => {
@@ -2783,7 +2794,6 @@ fn loadMemPtrIntoRegister(self: *Self, reg: Register, ptr_ty: Type, ptr: MCValue
}
fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type) InnerError!void {
_ = ptr_ty;
const abi_size = value_ty.abiSize(self.target.*);
switch (ptr) {
.none => unreachable,
@@ -3000,6 +3010,24 @@ fn store(self: *Self, ptr: MCValue, value: MCValue, ptr_ty: Type, value_ty: Type
try self.genInlineMemcpy(.{ .register = addr_reg.to64() }, value, .{ .immediate = abi_size }, .{});
},
.stack_offset => {
if (abi_size <= 8) {
// TODO this should really be a recursive call
const tmp_reg = try self.copyToTmpRegister(value_ty, value);
_ = try self.addInst(.{
.tag = .mov,
.ops = (Mir.Ops{
.reg1 = addr_reg.to64(),
.reg2 = tmp_reg,
.flags = 0b10,
}).encode(),
.data = .{ .imm = 0 },
});
return;
}
try self.genInlineMemcpy(.{ .register = addr_reg.to64() }, value, .{ .immediate = abi_size }, .{});
},
else => return self.fail("TODO implement storing {} to MCValue.memory", .{value}),
}
},