Add check to see that registers match in stencil generation

python · brandtbucher · Oct 30, 2024 · Sep 14, 2024 · Sep 14, 2024 · Sep 14, 2024
commit b8ae2183dc4d24aff8a6f38c8618b37da2cf20d8
@@ -132,15 +132,22 @@ class Hole:
     def __post_init__(self) -> None:
         self.func = _PATCH_FUNCS[self.kind]
 
-    def fold(self, other: typing.Self) -> typing.Self | None:
+    def fold(self, other: typing.Self, body: bytes) -> typing.Self | None:
         """Combine two holes into a single hole, if possible."""
+        instruction_a = int.from_bytes(body[self.offset : self.offset + 4], byteorder=sys.byteorder)
+        instruction_b = int.from_bytes(body[other.offset : other.offset + 4], byteorder=sys.byteorder)
+        reg_a = instruction_a & 0b11111
+        reg_b1 = instruction_b & 0b11111
+        reg_b2 = (instruction_b >> 5) & 0b11111
+
         if (
             self.offset + 4 == other.offset
             and self.value == other.value
             and self.symbol == other.symbol
             and self.addend == other.addend
             and self.func == "patch_aarch64_21rx"
             and other.func == "patch_aarch64_12x"
+            and reg_a == reg_b1 == reg_b2
         ):
             # These can *only* be properly relaxed when they appear together and
             # patch the same value:

@@ -50,7 +50,7 @@ def _dump_stencil(opname: str, group: _stencils.StencilGroup) -> typing.Iterator
             if skip:
                 skip = False
                 continue
-            if pair and (folded := hole.fold(pair)):
+            if pair and (folded := hole.fold(pair, stencil.body)):
                 skip = True
                 hole = folded
             yield f"    {hole.as_c(part)}"