Revert "[SimplifyCFG] Forward indirect switch condition value if it can help fold the PHI (#95932)"

This reverts commit 0c56fd0.
This is breaking https://lab.llvm.org/buildbot/#/builders/72/builds/483.

Author: dianqk

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -5818,8 +5818,7 @@ static bool ForwardSwitchConditionToPHI(SwitchInst *SI) {
   for (auto &ForwardingNode : ForwardingNodes) {
     PHINode *Phi = ForwardingNode.first;
     SmallVectorImpl<int> &Indexes = ForwardingNode.second;
-    // Check if it helps to fold PHI.
-    if (Indexes.size() < 2 && !llvm::is_contained(Phi->incoming_values(), SI->getCondition()))
+    if (Indexes.size() < 2)
       continue;
 
     for (int Index : Indexes)

llvm/test/CodeGen/AArch64/arm64-jumptable.ll

@@ -18,7 +18,7 @@ bb3:
 bb4:
   br label %exit.sink.split
 exit.sink.split:
-  %.sink = phi i32 [ 5, %bb4 ], [ %b, %bb1 ], [ 7, %bb3 ], [ %a, %entry ]
+  %.sink = phi i32 [ 5, %bb4 ], [ %b, %bb1 ], [ 3, %bb3 ], [ %a, %entry ]
   store i32 %.sink, ptr %to
   br label %exit
 exit:

llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll

@@ -59,76 +59,6 @@ return:                                           ; preds = %entry, %sw.bb4, %sw
   ret i32 %retval.0
 }
 
-; We should not forward `%m` to 1, as this does not simplify the CFG.
-define i32 @forward_one(i32 %m) {
-; NO_FWD-LABEL: @forward_one(
-; NO_FWD-NEXT:  entry:
-; NO_FWD-NEXT:    switch i32 [[M:%.*]], label [[SW_BB4:%.*]] [
-; NO_FWD-NEXT:      i32 0, label [[RETURN:%.*]]
-; NO_FWD-NEXT:      i32 1, label [[SW_BB1:%.*]]
-; NO_FWD-NEXT:      i32 2, label [[SW_BB2:%.*]]
-; NO_FWD-NEXT:      i32 3, label [[SW_BB3:%.*]]
-; NO_FWD-NEXT:    ]
-; NO_FWD:       sw.bb1:
-; NO_FWD-NEXT:    br label [[RETURN]]
-; NO_FWD:       sw.bb2:
-; NO_FWD-NEXT:    br label [[RETURN]]
-; NO_FWD:       sw.bb3:
-; NO_FWD-NEXT:    br label [[RETURN]]
-; NO_FWD:       sw.bb4:
-; NO_FWD-NEXT:    br label [[RETURN]]
-; NO_FWD:       return:
-; NO_FWD-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 4, [[SW_BB4]] ], [ 5, [[SW_BB3]] ], [ 6, [[SW_BB2]] ], [ 1, [[SW_BB1]] ], [ 8, [[ENTRY:%.*]] ]
-; NO_FWD-NEXT:    ret i32 [[RETVAL_0]]
-;
-; FWD-LABEL: @forward_one(
-; FWD-NEXT:  entry:
-; FWD-NEXT:    switch i32 [[M:%.*]], label [[SW_BB4:%.*]] [
-; FWD-NEXT:      i32 0, label [[RETURN:%.*]]
-; FWD-NEXT:      i32 1, label [[SW_BB1:%.*]]
-; FWD-NEXT:      i32 2, label [[SW_BB2:%.*]]
-; FWD-NEXT:      i32 3, label [[SW_BB3:%.*]]
-; FWD-NEXT:    ]
-; FWD:       sw.bb1:
-; FWD-NEXT:    br label [[RETURN]]
-; FWD:       sw.bb2:
-; FWD-NEXT:    br label [[RETURN]]
-; FWD:       sw.bb3:
-; FWD-NEXT:    br label [[RETURN]]
-; FWD:       sw.bb4:
-; FWD-NEXT:    br label [[RETURN]]
-; FWD:       return:
-; FWD-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 4, [[SW_BB4]] ], [ 5, [[SW_BB3]] ], [ 6, [[SW_BB2]] ], [ 1, [[SW_BB1]] ], [ 8, [[ENTRY:%.*]] ]
-; FWD-NEXT:    ret i32 [[RETVAL_0]]
-;
-entry:
-  switch i32 %m, label %sw.bb4 [
-  i32 0, label %sw.bb0
-  i32 1, label %sw.bb1
-  i32 2, label %sw.bb2
-  i32 3, label %sw.bb3
-  ]
-
-sw.bb0:                                           ; preds = %entry
-  br label %return
-
-sw.bb1:                                           ; preds = %entry
-  br label %return
-
-sw.bb2:                                           ; preds = %entry
-  br label %return
-
-sw.bb3:                                           ; preds = %entry
-  br label %return
-
-sw.bb4:                                           ; preds = %entry
-  br label %return
-
-return:                                           ; preds = %entry, %sw.bb4, %sw.bb3, %sw.bb2, %sw.bb1
-  %retval.0 = phi i32 [ 4, %sw.bb4 ], [ 5, %sw.bb3 ], [ 6, %sw.bb2 ], [ 1, %sw.bb1 ], [ 8, %sw.bb0 ]
-  ret i32 %retval.0
-}
-
 ; If 1 incoming phi value is a case constant of a switch, convert it to the switch condition:
 ; https://bugs.llvm.org/show_bug.cgi?id=34471
 ; This then subsequently should allow squashing of the other trivial case blocks.
@@ -185,60 +115,3 @@ return:
   ret i32 %r
 }
 
-; We can replace `[ 1, %bb2 ]` with `[ %arg1, %bb2 ]`.
-define { i64, i64 } @PR95919(i64 noundef %arg, i64 noundef %arg1) {
-; NO_FWD-LABEL: @PR95919(
-; NO_FWD-NEXT:  bb:
-; NO_FWD-NEXT:    switch i64 [[ARG1:%.*]], label [[BB3:%.*]] [
-; NO_FWD-NEXT:      i64 0, label [[BB5:%.*]]
-; NO_FWD-NEXT:      i64 1, label [[BB2:%.*]]
-; NO_FWD-NEXT:    ]
-; NO_FWD:       bb2:
-; NO_FWD-NEXT:    br label [[BB5]]
-; NO_FWD:       bb3:
-; NO_FWD-NEXT:    [[I:%.*]] = udiv i64 [[ARG:%.*]], [[ARG1]]
-; NO_FWD-NEXT:    [[I4:%.*]] = shl nuw i64 [[I]], 1
-; NO_FWD-NEXT:    br label [[BB5]]
-; NO_FWD:       bb5:
-; NO_FWD-NEXT:    [[I6:%.*]] = phi i64 [ [[I4]], [[BB3]] ], [ [[ARG]], [[BB2]] ], [ undef, [[BB:%.*]] ]
-; NO_FWD-NEXT:    [[I7:%.*]] = phi i64 [ 1, [[BB3]] ], [ 1, [[BB2]] ], [ [[ARG1]], [[BB]] ]
-; NO_FWD-NEXT:    [[I8:%.*]] = insertvalue { i64, i64 } poison, i64 [[I7]], 0
-; NO_FWD-NEXT:    [[I9:%.*]] = insertvalue { i64, i64 } [[I8]], i64 [[I6]], 1
-; NO_FWD-NEXT:    ret { i64, i64 } [[I9]]
-;
-; FWD-LABEL: @PR95919(
-; FWD-NEXT:  bb:
-; FWD-NEXT:    [[SWITCH:%.*]] = icmp ult i64 [[ARG1:%.*]], 2
-; FWD-NEXT:    br i1 [[SWITCH]], label [[BB5:%.*]], label [[BB3:%.*]]
-; FWD:       bb3:
-; FWD-NEXT:    [[I:%.*]] = udiv i64 [[ARG:%.*]], [[ARG1]]
-; FWD-NEXT:    [[I4:%.*]] = shl nuw i64 [[I]], 1
-; FWD-NEXT:    br label [[BB5]]
-; FWD:       bb5:
-; FWD-NEXT:    [[I6:%.*]] = phi i64 [ [[I4]], [[BB3]] ], [ [[ARG]], [[BB:%.*]] ]
-; FWD-NEXT:    [[I7:%.*]] = phi i64 [ 1, [[BB3]] ], [ [[ARG1]], [[BB]] ]
-; FWD-NEXT:    [[I8:%.*]] = insertvalue { i64, i64 } poison, i64 [[I7]], 0
-; FWD-NEXT:    [[I9:%.*]] = insertvalue { i64, i64 } [[I8]], i64 [[I6]], 1
-; FWD-NEXT:    ret { i64, i64 } [[I9]]
-;
-bb:
-  switch i64 %arg1, label %bb3 [
-  i64 0, label %bb5
-  i64 1, label %bb2
-  ]
-
-bb2: ; preds = %bb
-  br label %bb5
-
-bb3: ; preds = %bb
-  %i = udiv i64 %arg, %arg1
-  %i4 = shl nuw i64 %i, 1
-  br label %bb5
-
-bb5: ; preds = %bb3, %bb2, %bb
-  %i6 = phi i64 [ %i4, %bb3 ], [ %arg, %bb2 ], [ undef, %bb ]
-  %i7 = phi i64 [ 1, %bb3 ], [ 1, %bb2 ], [ %arg1, %bb ]
-  %i8 = insertvalue { i64, i64 } poison, i64 %i7, 0
-  %i9 = insertvalue { i64, i64 } %i8, i64 %i6, 1
-  ret { i64, i64 } %i9
-}

llvm/test/Transforms/SimplifyCFG/Hexagon/switch-to-lookup-table.ll

@@ -43,7 +43,7 @@ define i32 @foo(i32 %x) #0 section ".tcm_text" {
 ; DISABLE:       sw.default:
 ; DISABLE-NEXT:    br label [[RETURN]]
 ; DISABLE:       return:
-; DISABLE-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 33, [[SW_BB5]] ], [ 12, [[SW_BB4]] ], [ 22, [[SW_BB3]] ], [ 14, [[SW_BB2]] ], [ 20, [[SW_BB1]] ], [ 9, [[ENTRY:%.*]] ]
+; DISABLE-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ 19, [[SW_DEFAULT]] ], [ 5, [[SW_BB5]] ], [ 12, [[SW_BB4]] ], [ 22, [[SW_BB3]] ], [ 14, [[SW_BB2]] ], [ 20, [[SW_BB1]] ], [ 9, [[ENTRY:%.*]] ]
 ; DISABLE-NEXT:    ret i32 [[RETVAL_0]]
 ;
 entry:
@@ -81,7 +81,7 @@ sw.bb4:                                           ; preds = %entry
   br label %return
 
 sw.bb5:                                           ; preds = %entry
-  store i32 33, ptr %retval, align 4
+  store i32 5, ptr %retval, align 4
   br label %return
 
 sw.default:                                       ; preds = %entry