[GlobalISel] Fix misaligned read after #74429

vitalybuka · vitalybuka · commit eabf7ec3f3d4 · 2023-12-13T14:04:59.000-08:00
diff --git a/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h b/llvm/include/llvm/CodeGen/GlobalISel/GIMatchTableExecutor.h
@@ -690,7 +690,9 @@ class GIMatchTableExecutor {
   bool isObviouslySafeToFold(MachineInstr &MI, MachineInstr &IntoMI) const;
 
   template <typename Ty> static Ty readBytesAs(const uint8_t *MatchTable) {
-    return *reinterpret_cast<const Ty *>(MatchTable);
+    Ty res;
+    memcpy(&res, MatchTable, sizeof(res));
+    return res;
   }
 };
 

Original file line number	Diff line number	Diff line change
`@@ -690,7 +690,9 @@ class GIMatchTableExecutor {`
`690`	`690`	`bool isObviouslySafeToFold(MachineInstr &MI, MachineInstr &IntoMI) const;`
`691`	`691`
`692`	`692`	`template <typename Ty> static Ty readBytesAs(const uint8_t *MatchTable) {`
`693`		`- return reinterpret_cast<const Ty >(MatchTable);`
	`693`	`+ Ty res;`
	`694`	`+ memcpy(&res, MatchTable, sizeof(res));`
	`695`	`+ return res;`
`694`	`696`	`}`
`695`	`697`	`};`
`696`	`698`