zig

commit 4e581427d1fee46cdcab088cb2c1d7ad51b06239 (tree)
parent b36ea592b86ef20473697ded24a27bb644941de8
Author: Jacob Young <jacobly0@users.noreply.github.com>
Date:   Thu,  9 Jan 2025 07:39:34 -0500

x86_64: fix miscomp where in use register is marked as free

Diffstat:
M
src/register_manager.zig
 | 
14
+++++++-------

1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/src/register_manager.zig b/src/register_manager.zig
@@ -352,15 +352,15 @@ pub fn RegisterManager(
         ) AllocateRegistersError!void {
             log.debug("getReg {} for inst {?}", .{ regAtTrackedIndex(tracked_index), inst });
             if (!self.isRegIndexFree(tracked_index)) {
-                self.markRegIndexAllocated(tracked_index);
-
                 // Move the instruction that was previously there to a
                 // stack allocation.
-                const spilled_inst = self.registers[tracked_index];
-                if (inst) |tracked_inst| self.registers[tracked_index] = tracked_inst;
-                try self.getFunction().spillInstruction(regAtTrackedIndex(tracked_index), spilled_inst);
-                if (inst == null) self.freeRegIndex(tracked_index);
-            } else self.getRegIndexAssumeFree(tracked_index, inst);
+                try self.getFunction().spillInstruction(
+                    regAtTrackedIndex(tracked_index),
+                    self.registers[tracked_index],
+                );
+                self.freeRegIndex(tracked_index);
+            }
+            self.getRegIndexAssumeFree(tracked_index, inst);
         }
         pub fn getReg(self: *Self, reg: Register, inst: ?Air.Inst.Index) AllocateRegistersError!void {
             log.debug("getting reg: {}", .{reg});