fix: add Select condition check

woruyu · woruyu · commit ea75544aa98a · 2025-07-02T16:47:35.000+08:00
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -13138,6 +13138,9 @@ static SDValue combineVSelectWithAllOnesOrZeros(SDValue Cond, SDValue TVal,
     }
   }
 
+  assert(DAG.ComputeNumSignBits(Cond) == CondVT.getScalarSizeInBits() &&
+         "Select condition no longer all-sign bits");
+
   // select Cond, -1, 0 → bitcast Cond
   if (IsTAllOne && IsFAllZero)
     return DAG.getBitcast(VT, Cond);

Original file line number	Diff line number	Diff line change
`@@ -13138,6 +13138,9 @@ static SDValue combineVSelectWithAllOnesOrZeros(SDValue Cond, SDValue TVal,`
`13138`	`13138`	`}`
`13139`	`13139`	`}`
`13140`	`13140`
	`13141`	`+ assert(DAG.ComputeNumSignBits(Cond) == CondVT.getScalarSizeInBits() &&`
	`13142`	`+ "Select condition no longer all-sign bits");`
	`13143`	`+`
`13141`	`13144`	`// select Cond, -1, 0 → bitcast Cond`
`13142`	`13145`	`if (IsTAllOne && IsFAllZero)`
`13143`	`13146`	`return DAG.getBitcast(VT, Cond);`