[VPlan] Don't fold live ins with both scalar and vector operands

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -980,10 +980,11 @@ static Value *tryToFoldLiveIns(const VPRecipeBase &R, unsigned Opcode,
     return Folder.FoldGEP(IntegerType::getInt8Ty(TypeInfo.getContext()), Ops[0],
                           Ops[1],
                           cast<VPRecipeWithIRFlags>(R).getGEPNoWrapFlags());
-  case Instruction::InsertElement:
-    return Folder.FoldInsertElement(Ops[0], Ops[1], Ops[2]);
+  // An extract of a live-in is an extract of a broadcast, so return the
+  // broadcasted element.
   case Instruction::ExtractElement:
-    return Folder.FoldExtractElement(Ops[0], Ops[1]);
+    assert(!Ops[0]->getType()->isVectorTy() && "Live-ins should be scalar");
+    return Ops[0];
   }
   return nullptr;
 }

llvm/test/Transforms/LoopVectorize/pr154045-dont-fold-extractelement-livein.ll

@@ -0,0 +1,73 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 5
+; RUN: opt -p loop-vectorize -force-vector-width=2 -force-widen-divrem-via-safe-divisor=false -S %s | FileCheck %s
+
+; Make sure we don't try to fold a Instruction::ExtractElement ir<0>, ir<0>,
+; since we can't materialize the live-in for the vector operand.
+
+define void @pr154045(ptr %p, i1 %c, i64 %x) {
+; CHECK-LABEL: define void @pr154045(
+; CHECK-SAME: ptr [[P:%.*]], i1 [[C:%.*]], i64 [[X:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x i1> poison, i1 [[C]], i64 0
+; CHECK-NEXT:    [[BROADCAST_SPLAT:%.*]] = shufflevector <2 x i1> [[BROADCAST_SPLATINSERT]], <2 x i1> poison, <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[TMP0:%.*]] = xor <2 x i1> [[BROADCAST_SPLAT]], splat (i1 true)
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[TMP1:%.*]] = extractelement <2 x i1> [[TMP0]], i32 0
+; CHECK-NEXT:    br i1 [[TMP1]], label %[[PRED_SREM_IF:.*]], label %[[PRED_SREM_CONTINUE:.*]]
+; CHECK:       [[PRED_SREM_IF]]:
+; CHECK-NEXT:    br label %[[PRED_SREM_CONTINUE]]
+; CHECK:       [[PRED_SREM_CONTINUE]]:
+; CHECK-NEXT:    [[TMP2:%.*]] = extractelement <2 x i1> [[TMP0]], i32 1
+; CHECK-NEXT:    br i1 [[TMP2]], label %[[PRED_SREM_IF1:.*]], label %[[PRED_SREM_CONTINUE2:.*]]
+; CHECK:       [[PRED_SREM_IF1]]:
+; CHECK-NEXT:    br label %[[PRED_SREM_CONTINUE2]]
+; CHECK:       [[PRED_SREM_CONTINUE2]]:
+; CHECK-NEXT:    store i32 0, ptr [[P]], align 4
+; CHECK-NEXT:    br label %[[MIDDLE_BLOCK:.*]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br label %[[EXIT:.*]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LATCH:.*]] ]
+; CHECK-NEXT:    br i1 [[C]], label %[[LATCH]], label %[[ELSE:.*]]
+; CHECK:       [[ELSE]]:
+; CHECK-NEXT:    [[REM:%.*]] = srem i64 0, [[X]]
+; CHECK-NEXT:    br label %[[LATCH]]
+; CHECK:       [[LATCH]]:
+; CHECK-NEXT:    [[PHI:%.*]] = phi i64 [ [[REM]], %[[ELSE]] ], [ 0, %[[LOOP]] ]
+; CHECK-NEXT:    [[PHI_TRUNC:%.*]] = trunc i64 [[PHI]] to i32
+; CHECK-NEXT:    [[SHL:%.*]] = shl i32 [[PHI_TRUNC]], 0
+; CHECK-NEXT:    store i32 [[SHL]], ptr [[P]], align 4
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i64 [[IV]], 1
+; CHECK-NEXT:    br i1 [[EXITCOND]], label %[[EXIT]], label %[[LOOP]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
+  br i1 %c, label %latch, label %else
+
+else:
+  %rem = srem i64 0, %x
+  br label %latch
+
+latch:
+  %phi = phi i64 [ %rem, %else ], [ 0, %loop ]
+  %phi.trunc = trunc i64 %phi to i32
+  %shl = shl i32 %phi.trunc, 0
+  store i32 %shl, ptr %p
+  %iv.next = add i64 %iv, 1
+  %exitcond = icmp eq i64 %iv, 1
+  br i1 %exitcond, label %exit, label %loop
+
+exit:
+  ret void
+}