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stage2: codegen: fix reuseOperand not doing death bookkeeping

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This commit is contained in:
Andrew Kelley
2020-08-26 01:00:04 -07:00
parent 237d9a105d
commit 0c5faa61ae
3 changed files with 79 additions and 2 deletions
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7
src-self-hosted/codegen.zig
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@@ -632,6 +632,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
/// Asserts there is already capacity to insert into top branch inst_table.
fn processDeath(self: *Self, inst: *ir.Inst) void {
if (inst.tag == .constant) return; // Constants are immortal.
// When editing this function, note that the logic must synchronize with `reuseOperand`.
const prev_value = self.getResolvedInstValue(inst);
const branch = &self.branch_stack.items[self.branch_stack.items.len - 1];
branch.inst_table.putAssumeCapacity(inst, .dead);
@@ -951,6 +952,10 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
// Prevent the operand deaths processing code from deallocating it.
inst.clearOperandDeath(op_index);
// That makes us responsible for doing the rest of the stuff that processDeath would have done.
const branch = &self.branch_stack.items[self.branch_stack.items.len - 1];
branch.inst_table.putAssumeCapacity(inst.getOperand(op_index).?, .dead);
return true;
}
@@ -1666,7 +1671,7 @@ fn Function(comptime arch: std.Target.Cpu.Arch) type {
// The instruction is only overridden in the else branch.
var i: usize = self.branch_stack.items.len - 2;
while (true) {
i -= 1;
i -= 1; // If this overflows, the question is: why wasn't the instruction marked dead?
if (self.branch_stack.items[i].inst_table.get(else_entry.key)) |mcv| {
assert(mcv != .dead);
break :blk mcv;