[LV]Process alloca in isPredicatedInst for tail-folded analysis.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -3342,7 +3342,7 @@ bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
   if (!blockNeedsPredicationForAnyReason(I->getParent()) ||
       isSafeToSpeculativelyExecute(I) ||
       (isa<LoadInst, StoreInst, CallInst>(I) && !Legal->isMaskRequired(I)) ||
-      isa<BranchInst, PHINode>(I))
+      isa<BranchInst, PHINode, AllocaInst>(I))
     return false;
 
   // If the instruction was executed conditionally in the original scalar loop,

llvm/test/Transforms/LoopVectorize/tail-folding-alloca-in-loop.ll

@@ -0,0 +1,91 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S --passes=loop-vectorize -prefer-predicate-over-epilogue=predicate-dont-vectorize -force-vector-width=4  < %s | FileCheck %s
+
+define i32 @test(ptr %vf1, i64 %n) {
+; CHECK-LABEL: define i32 @test(
+; CHECK-SAME: ptr [[VF1:%.*]], i64 [[N:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_STORE_CONTINUE6:.*]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i64> [ <i64 0, i64 1, i64 2, i64 3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[PRED_STORE_CONTINUE6]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ule <4 x i64> [[VEC_IND]], <i64 200, i64 200, i64 200, i64 200>
+; CHECK-NEXT:    [[TMP1:%.*]] = extractelement <4 x i1> [[TMP0]], i32 0
+; CHECK-NEXT:    br i1 [[TMP1]], label %[[PRED_STORE_IF:.*]], label %[[PRED_STORE_CONTINUE:.*]]
+; CHECK:       [[PRED_STORE_IF]]:
+; CHECK-NEXT:    [[TMP2:%.*]] = add i64 [[INDEX]], 0
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds ptr, ptr [[VF1]], i64 [[TMP2]]
+; CHECK-NEXT:    [[TMP4:%.*]] = alloca i8, i64 [[N]], align 16
+; CHECK-NEXT:    store ptr [[TMP4]], ptr [[TMP3]], align 8
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE]]
+; CHECK:       [[PRED_STORE_CONTINUE]]:
+; CHECK-NEXT:    [[TMP5:%.*]] = extractelement <4 x i1> [[TMP0]], i32 1
+; CHECK-NEXT:    br i1 [[TMP5]], label %[[PRED_STORE_IF1:.*]], label %[[PRED_STORE_CONTINUE2:.*]]
+; CHECK:       [[PRED_STORE_IF1]]:
+; CHECK-NEXT:    [[TMP6:%.*]] = add i64 [[INDEX]], 1
+; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds ptr, ptr [[VF1]], i64 [[TMP6]]
+; CHECK-NEXT:    [[TMP8:%.*]] = alloca i8, i64 [[N]], align 16
+; CHECK-NEXT:    store ptr [[TMP8]], ptr [[TMP7]], align 8
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE2]]
+; CHECK:       [[PRED_STORE_CONTINUE2]]:
+; CHECK-NEXT:    [[TMP9:%.*]] = extractelement <4 x i1> [[TMP0]], i32 2
+; CHECK-NEXT:    br i1 [[TMP9]], label %[[PRED_STORE_IF3:.*]], label %[[PRED_STORE_CONTINUE4:.*]]
+; CHECK:       [[PRED_STORE_IF3]]:
+; CHECK-NEXT:    [[TMP10:%.*]] = add i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP11:%.*]] = getelementptr inbounds ptr, ptr [[VF1]], i64 [[TMP10]]
+; CHECK-NEXT:    [[TMP12:%.*]] = alloca i8, i64 [[N]], align 16
+; CHECK-NEXT:    store ptr [[TMP12]], ptr [[TMP11]], align 8
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE4]]
+; CHECK:       [[PRED_STORE_CONTINUE4]]:
+; CHECK-NEXT:    [[TMP13:%.*]] = extractelement <4 x i1> [[TMP0]], i32 3
+; CHECK-NEXT:    br i1 [[TMP13]], label %[[PRED_STORE_IF5:.*]], label %[[PRED_STORE_CONTINUE6]]
+; CHECK:       [[PRED_STORE_IF5]]:
+; CHECK-NEXT:    [[TMP14:%.*]] = add i64 [[INDEX]], 3
+; CHECK-NEXT:    [[TMP15:%.*]] = getelementptr inbounds ptr, ptr [[VF1]], i64 [[TMP14]]
+; CHECK-NEXT:    [[TMP16:%.*]] = alloca i8, i64 [[N]], align 16
+; CHECK-NEXT:    store ptr [[TMP16]], ptr [[TMP15]], align 8
+; CHECK-NEXT:    br label %[[PRED_STORE_CONTINUE6]]
+; CHECK:       [[PRED_STORE_CONTINUE6]]:
+; CHECK-NEXT:    [[INDEX_NEXT]] = add i64 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i64> [[VEC_IND]], <i64 4, i64 4, i64 4, i64 4>
+; CHECK-NEXT:    [[TMP17:%.*]] = icmp eq i64 [[INDEX_NEXT]], 204
+; CHECK-NEXT:    br i1 [[TMP17]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    br i1 true, label %[[exit:.*]], label %[[SCALAR_PH]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 204, %[[MIDDLE_BLOCK]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    br label %[[FOR_BODY:.*]]
+; CHECK:       [[FOR_BODY]]:
+; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[INDVARS_IV_NEXT:%.*]], %[[FOR_BODY]] ]
+; CHECK-NEXT:    [[TMP18:%.*]] = alloca i8, i64 [[N]], align 16
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds ptr, ptr [[VF1]], i64 [[INDVARS_IV]]
+; CHECK-NEXT:    store ptr [[TMP18]], ptr [[ARRAYIDX]], align 8
+; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
+; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[INDVARS_IV]], 200
+; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label %[[exit]], label %[[FOR_BODY]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[exit]]:
+; CHECK-NEXT:    ret i32 0
+;
+entry:
+  br label %for.body
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %0 = alloca i8, i64 %n, align 16
+  %arrayidx = getelementptr inbounds ptr, ptr %vf1, i64 %indvars.iv
+  store ptr %0, ptr %arrayidx, align 8
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %exitcond.not = icmp eq i64 %indvars.iv, 200
+  br i1 %exitcond.not, label %exit, label %for.body
+
+exit:
+  ret i32 0
+}
+;.
+; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]], [[META2:![0-9]+]]}
+; CHECK: [[META1]] = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK: [[META2]] = !{!"llvm.loop.unroll.runtime.disable"}
+; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META2]], [[META1]]}
+;.