[llvm] [WIP][VPlan] Use BlockFrequencyInfo in getPredBlockCostDivisor (PR #158690)

[Luke Lau via llvm-commits]

================
@@ -612,63 +612,18 @@ define void @low_trip_count_fold_tail_scalarized_store(ptr %dst) {
 ;
 ; COMMON-LABEL: define void @low_trip_count_fold_tail_scalarized_store(
 ; COMMON-SAME: ptr [[DST:%.*]]) {
-; COMMON-NEXT:  [[ENTRY:.*:]]
-; COMMON-NEXT:    br label %[[VECTOR_PH:.*]]
-; COMMON:       [[VECTOR_PH]]:
-; COMMON-NEXT:    br label %[[VECTOR_BODY:.*]]
-; COMMON:       [[VECTOR_BODY]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF:.*]], label %[[PRED_STORE_CONTINUE:.*]]
-; COMMON:       [[PRED_STORE_IF]]:
-; COMMON-NEXT:    [[TMP0:%.*]] = getelementptr i8, ptr [[DST]], i64 0
-; COMMON-NEXT:    store i8 0, ptr [[TMP0]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE]]
-; COMMON:       [[PRED_STORE_CONTINUE]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF1:.*]], label %[[PRED_STORE_CONTINUE2:.*]]
-; COMMON:       [[PRED_STORE_IF1]]:
-; COMMON-NEXT:    [[TMP1:%.*]] = getelementptr i8, ptr [[DST]], i64 1
-; COMMON-NEXT:    store i8 1, ptr [[TMP1]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE2]]
-; COMMON:       [[PRED_STORE_CONTINUE2]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF3:.*]], label %[[PRED_STORE_CONTINUE4:.*]]
-; COMMON:       [[PRED_STORE_IF3]]:
-; COMMON-NEXT:    [[TMP2:%.*]] = getelementptr i8, ptr [[DST]], i64 2
-; COMMON-NEXT:    store i8 2, ptr [[TMP2]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE4]]
-; COMMON:       [[PRED_STORE_CONTINUE4]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF5:.*]], label %[[PRED_STORE_CONTINUE6:.*]]
-; COMMON:       [[PRED_STORE_IF5]]:
-; COMMON-NEXT:    [[TMP3:%.*]] = getelementptr i8, ptr [[DST]], i64 3
-; COMMON-NEXT:    store i8 3, ptr [[TMP3]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE6]]
-; COMMON:       [[PRED_STORE_CONTINUE6]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF7:.*]], label %[[PRED_STORE_CONTINUE8:.*]]
-; COMMON:       [[PRED_STORE_IF7]]:
-; COMMON-NEXT:    [[TMP4:%.*]] = getelementptr i8, ptr [[DST]], i64 4
-; COMMON-NEXT:    store i8 4, ptr [[TMP4]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE8]]
-; COMMON:       [[PRED_STORE_CONTINUE8]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF9:.*]], label %[[PRED_STORE_CONTINUE10:.*]]
-; COMMON:       [[PRED_STORE_IF9]]:
-; COMMON-NEXT:    [[TMP5:%.*]] = getelementptr i8, ptr [[DST]], i64 5
-; COMMON-NEXT:    store i8 5, ptr [[TMP5]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE10]]
-; COMMON:       [[PRED_STORE_CONTINUE10]]:
-; COMMON-NEXT:    br i1 true, label %[[PRED_STORE_IF11:.*]], label %[[PRED_STORE_CONTINUE12:.*]]
-; COMMON:       [[PRED_STORE_IF11]]:
-; COMMON-NEXT:    [[TMP6:%.*]] = getelementptr i8, ptr [[DST]], i64 6
-; COMMON-NEXT:    store i8 6, ptr [[TMP6]], align 1
-; COMMON-NEXT:    br label %[[PRED_STORE_CONTINUE12]]
-; COMMON:       [[PRED_STORE_CONTINUE12]]:
-; COMMON-NEXT:    br i1 false, label %[[PRED_STORE_IF13:.*]], label %[[EXIT:.*]]
-; COMMON:       [[PRED_STORE_IF13]]:
-; COMMON-NEXT:    [[TMP7:%.*]] = getelementptr i8, ptr [[DST]], i64 7
-; COMMON-NEXT:    store i8 7, ptr [[TMP7]], align 1
-; COMMON-NEXT:    br label %[[EXIT]]
-; COMMON:       [[EXIT]]:
-; COMMON-NEXT:    br label %[[SCALAR_PH:.*]]
-; COMMON:       [[SCALAR_PH]]:
-; COMMON-NEXT:    br [[EXIT1:label %.*]]
-; COMMON:       [[SCALAR_PH1:.*:]]
+; COMMON-NEXT:  [[ENTRY:.*]]:
+; COMMON-NEXT:    br label %[[EXIT1:.*]]
+; COMMON:       [[EXIT1]]:
+; COMMON-NEXT:    [[IV:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[IV_NEXT:%.*]], %[[EXIT1]] ]
+; COMMON-NEXT:    [[IV_TRUNC:%.*]] = trunc i64 [[IV]] to i8
+; COMMON-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[DST]], i64 [[IV]]
+; COMMON-NEXT:    store i8 [[IV_TRUNC]], ptr [[GEP]], align 1
+; COMMON-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
+; COMMON-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV_NEXT]], 7
+; COMMON-NEXT:    br i1 [[EC]], label %[[SCALAR_PH1:.*]], label %[[EXIT1]]
+; COMMON:       [[SCALAR_PH1]]:
+; COMMON-NEXT:    ret void
----------------
lukel97 wrote:

Previously all the predicated scalar stores were discounted by x0.5 in computePredInstDiscount. BFI now correctly returns that this block is always executed so the VF=1 plan is no longer discounted.

https://github.com/llvm/llvm-project/pull/158690