Revert "SimplifyCFG: Delay creation of bitmaps"

This reverts commit 27179dc.

Author: OutOfCache

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -6469,9 +6469,6 @@ class SwitchReplacement {
   /// Return true if the replacement is a lookup table.
   bool isLookupTable();
 
-  /// Return true if the replacement is a bitmap.
-  bool isBitMap();
-
 private:
   // Depending on the switch, there are different alternatives.
   enum {
@@ -6762,8 +6759,6 @@ Constant *SwitchReplacement::getDefaultValue() { return DefaultValue; }
 
 bool SwitchReplacement::isLookupTable() { return Kind == LookupTableKind; }
 
-bool SwitchReplacement::isBitMap() { return Kind == BitMapKind; }
-
 static bool isSwitchDense(uint64_t NumCases, uint64_t CaseRange) {
   // 40% is the default density for building a jump table in optsize/minsize
   // mode. See also TargetLoweringBase::isSuitableForJumpTable(), which this
@@ -7113,14 +7108,6 @@ static bool simplifySwitchLookup(SwitchInst *SI, IRBuilder<> &Builder,
        Fn->getFnAttribute("no-jump-tables").getValueAsBool()))
     return false;
 
-  bool AnyBitMaps = any_of(PhiToReplacementMap,
-                           [](auto &KV) { return KV.second.isBitMap(); });
-
-  // Bitmaps can also cause missed optimizations due to difficult-to-analyze
-  // code. Delay the creation of bitmaps until later in the pipeline.
-  if (AnyBitMaps && !ConvertSwitchToLookupTable)
-    return false;
-
   Builder.SetInsertPoint(SI);
   // TableIndex is the switch condition - TableIndexOffset if we don't
   // use the condition directly

llvm/test/Transforms/PhaseOrdering/X86/merge-functions.ll

@@ -89,7 +89,7 @@ bb3:                                              ; preds = %bb1, %bb2
 
 define i1 @test2(i32 %c) {
 ; CHECK-LABEL: @test2(
-; CHECK-NEXT:    [[TMP2:%.*]] = tail call noundef i1 @test1(i32 [[TMP0:%.*]]) #[[ATTR0:[0-9]+]]
+; CHECK-NEXT:    [[TMP2:%.*]] = tail call i1 @test1(i32 [[TMP0:%.*]]) #[[ATTR0:[0-9]+]]
 ; CHECK-NEXT:    ret i1 [[TMP2]]
 ;
 entry:

llvm/test/Transforms/SimplifyCFG/switch-transformations-no-lut.ll

@@ -166,23 +166,11 @@ end:
 define i4 @bitmap_no_default(i32 %x) {
 ; OPTNOLUT-LABEL: define i4 @bitmap_no_default(
 ; OPTNOLUT-SAME: i32 [[X:%.*]]) {
-; OPTNOLUT-NEXT:  [[ENTRY:.*]]:
-; OPTNOLUT-NEXT:    switch i32 [[X]], label %[[DEFAULT:.*]] [
-; OPTNOLUT-NEXT:      i32 0, label %[[END:.*]]
-; OPTNOLUT-NEXT:      i32 1, label %[[CASE1:.*]]
-; OPTNOLUT-NEXT:      i32 2, label %[[CASE2:.*]]
-; OPTNOLUT-NEXT:      i32 3, label %[[CASE3:.*]]
-; OPTNOLUT-NEXT:    ]
-; OPTNOLUT:       [[CASE1]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[CASE2]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[CASE3]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[DEFAULT]]:
-; OPTNOLUT-NEXT:    unreachable
-; OPTNOLUT:       [[END]]:
-; OPTNOLUT-NEXT:    [[SWITCH_MASKED:%.*]] = phi i4 [ 2, %[[CASE1]] ], [ 4, %[[CASE2]] ], [ -8, %[[CASE3]] ], [ 0, %[[ENTRY]] ]
+; OPTNOLUT-NEXT:  [[ENTRY:.*:]]
+; OPTNOLUT-NEXT:    [[SWITCH_CAST:%.*]] = trunc i32 [[X]] to i16
+; OPTNOLUT-NEXT:    [[SWITCH_SHIFTAMT:%.*]] = mul nuw nsw i16 [[SWITCH_CAST]], 4
+; OPTNOLUT-NEXT:    [[SWITCH_DOWNSHIFT:%.*]] = lshr i16 -31712, [[SWITCH_SHIFTAMT]]
+; OPTNOLUT-NEXT:    [[SWITCH_MASKED:%.*]] = trunc i16 [[SWITCH_DOWNSHIFT]] to i4
 ; OPTNOLUT-NEXT:    ret i4 [[SWITCH_MASKED]]
 ;
 ; TTINOLUT-LABEL: define i4 @bitmap_no_default(
@@ -221,23 +209,13 @@ end:
 define i4 @bitmap_with_default(i32 %x) {
 ; OPTNOLUT-LABEL: define i4 @bitmap_with_default(
 ; OPTNOLUT-SAME: i32 [[X:%.*]]) {
-; OPTNOLUT-NEXT:  [[ENTRY:.*]]:
-; OPTNOLUT-NEXT:    switch i32 [[X]], label %[[DEFAULT:.*]] [
-; OPTNOLUT-NEXT:      i32 0, label %[[END:.*]]
-; OPTNOLUT-NEXT:      i32 1, label %[[CASE1:.*]]
-; OPTNOLUT-NEXT:      i32 2, label %[[CASE2:.*]]
-; OPTNOLUT-NEXT:      i32 3, label %[[CASE3:.*]]
-; OPTNOLUT-NEXT:    ]
-; OPTNOLUT:       [[CASE1]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[CASE2]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[CASE3]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[DEFAULT]]:
-; OPTNOLUT-NEXT:    br label %[[END]]
-; OPTNOLUT:       [[END]]:
-; OPTNOLUT-NEXT:    [[IDX:%.*]] = phi i4 [ 2, %[[CASE1]] ], [ 4, %[[CASE2]] ], [ -8, %[[CASE3]] ], [ -1, %[[DEFAULT]] ], [ 0, %[[ENTRY]] ]
+; OPTNOLUT-NEXT:  [[ENTRY:.*:]]
+; OPTNOLUT-NEXT:    [[TMP0:%.*]] = icmp ult i32 [[X]], 4
+; OPTNOLUT-NEXT:    [[SWITCH_CAST:%.*]] = trunc i32 [[X]] to i16
+; OPTNOLUT-NEXT:    [[SWITCH_SHIFTAMT:%.*]] = mul nuw nsw i16 [[SWITCH_CAST]], 4
+; OPTNOLUT-NEXT:    [[SWITCH_DOWNSHIFT:%.*]] = lshr i16 -31712, [[SWITCH_SHIFTAMT]]
+; OPTNOLUT-NEXT:    [[SWITCH_MASKED:%.*]] = trunc i16 [[SWITCH_DOWNSHIFT]] to i4
+; OPTNOLUT-NEXT:    [[IDX:%.*]] = select i1 [[TMP0]], i4 [[SWITCH_MASKED]], i4 -1
 ; OPTNOLUT-NEXT:    ret i4 [[IDX]]
 ;
 ; TTINOLUT-LABEL: define i4 @bitmap_with_default(