Revert "[InstCombine] Fix infinite loop due to bitcast <-> phi transforms" (#35)
This reverts commit 8813358d42d15db1378d192521e6a26f7f62e6a5, which was
incorrect without dependent changes.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index a0fa884..2c9ba20 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -2234,14 +2234,9 @@
if (auto *C = dyn_cast<Constant>(V)) {
NewV = ConstantExpr::getBitCast(C, DestTy);
} else if (auto *LI = dyn_cast<LoadInst>(V)) {
- // Explicitly perform load combine to make sure no opposing transform
- // can remove the bitcast in the meantime and trigger an infinite loop.
- Builder.SetInsertPoint(LI);
- NewV = combineLoadToNewType(*LI, DestTy);
- // Remove the old load and its use in the old phi, which itself becomes
- // dead once the whole transform finishes.
- replaceInstUsesWith(*LI, UndefValue::get(LI->getType()));
- eraseInstFromFunction(*LI);
+ Builder.SetInsertPoint(LI->getNextNode());
+ NewV = Builder.CreateBitCast(LI, DestTy);
+ Worklist.Add(LI);
} else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
NewV = BCI->getOperand(0);
} else if (auto *PrevPN = dyn_cast<PHINode>(V)) {
diff --git a/llvm/test/Transforms/InstCombine/pr44245.ll b/llvm/test/Transforms/InstCombine/pr44245.ll
deleted file mode 100644
index f75e26e..0000000
--- a/llvm/test/Transforms/InstCombine/pr44245.ll
+++ /dev/null
@@ -1,192 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -S -instcombine -instcombine-infinite-loop-threshold=2 < %s | FileCheck %s
-
-; This used to cause on infinite instcombine loop.
-
-define void @test(i1 %c) {
-; CHECK-LABEL: @test(
-; CHECK-NEXT: bb16:
-; CHECK-NEXT: br i1 [[C:%.*]], label [[BB17:%.*]], label [[BB24:%.*]]
-; CHECK: bb17:
-; CHECK-NEXT: [[TMP0:%.*]] = phi i8* [ [[TMP1:%.*]], [[BB47:%.*]] ], [ undef, [[BB16:%.*]] ]
-; CHECK-NEXT: store i8* [[TMP0]], i8** undef, align 8
-; CHECK-NEXT: ret void
-; CHECK: bb24:
-; CHECK-NEXT: br i1 [[C]], label [[BB44:%.*]], label [[BB49:%.*]]
-; CHECK: bb44:
-; CHECK-NEXT: [[TMP467:%.*]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb47:
-; CHECK-NEXT: [[TMP1]] = phi i8* [ [[TMP2:%.*]], [[BB150:%.*]] ], [ [[TMP1221:%.*]], [[BB119:%.*]] ], [ [[TMP1032:%.*]], [[BB101:%.*]] ], [ [[TMP933:%.*]], [[BB91:%.*]] ], [ [[TMP834:%.*]], [[BB81:%.*]] ], [ [[TMP705:%.*]], [[BB67:%.*]] ], [ [[TMP586:%.*]], [[BB56:%.*]] ], [ [[TMP467]], [[BB44]] ]
-; CHECK-NEXT: br label [[BB17]]
-; CHECK: bb49:
-; CHECK-NEXT: br i1 [[C]], label [[BB56]], label [[BB59:%.*]]
-; CHECK: bb56:
-; CHECK-NEXT: [[TMP586]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb59:
-; CHECK-NEXT: br i1 [[C]], label [[BB67]], label [[BB71:%.*]]
-; CHECK: bb67:
-; CHECK-NEXT: [[TMP705]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb71:
-; CHECK-NEXT: br i1 [[C]], label [[BB81]], label [[BB84:%.*]]
-; CHECK: bb81:
-; CHECK-NEXT: [[TMP834]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb84:
-; CHECK-NEXT: br i1 [[C]], label [[BB91]], label [[BB94:%.*]]
-; CHECK: bb91:
-; CHECK-NEXT: [[TMP933]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb94:
-; CHECK-NEXT: br i1 [[C]], label [[BB101]], label [[BB104:%.*]]
-; CHECK: bb101:
-; CHECK-NEXT: [[TMP1032]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb104:
-; CHECK-NEXT: br i1 [[C]], label [[BB119]], label [[BB123:%.*]]
-; CHECK: bb119:
-; CHECK-NEXT: [[TMP1221]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb123:
-; CHECK-NEXT: br i1 [[C]], label [[BB147:%.*]], label [[BB152:%.*]]
-; CHECK: bb147:
-; CHECK-NEXT: [[TMP1499:%.*]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: br label [[BB150]]
-; CHECK: bb150:
-; CHECK-NEXT: [[TMP2]] = phi i8* [ [[TMP1848:%.*]], [[BB152]] ], [ [[TMP1499]], [[BB147]] ]
-; CHECK-NEXT: br label [[BB47]]
-; CHECK: bb152:
-; CHECK-NEXT: [[TMP1848]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
-; CHECK-NEXT: call void undef()
-; CHECK-NEXT: br label [[BB150]]
-;
-bb16: ; preds = %bb
- br i1 %c, label %bb17, label %bb24
-
-bb17: ; preds = %bb47, %bb17
- %0 = phi i8* [ %1, %bb47 ], [ undef, %bb16 ]
- store i8* %0, i8** undef, align 8
- ret void
-
-bb24: ; preds = %bb24
- br i1 %c, label %bb44, label %bb49
-
-bb44: ; preds = %bb43
- %tmp46 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb47: ; preds = %bb150, %bb119, %bb101, %bb91, %bb81, %bb67, %bb56, %bb44
- %.in1 = phi i64* [ %.in, %bb150 ], [ %tmp122, %bb119 ], [ %tmp103, %bb101 ], [ %tmp93, %bb91 ], [ %tmp83, %bb81 ], [ %tmp70, %bb67 ], [ %tmp58, %bb56 ], [ %tmp46, %bb44 ]
- %1 = bitcast i64* %.in1 to i8*
- br label %bb17
-
-bb49: ; preds = %bb49
- br i1 %c, label %bb56, label %bb59
-
-bb56: ; preds = %bb55
- %tmp58 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb59: ; preds = %bb59
- br i1 %c, label %bb67, label %bb71
-
-bb67: ; preds = %bb66
- %tmp70 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb71: ; preds = %bb71
- br i1 %c, label %bb81, label %bb84
-
-bb81: ; preds = %bb80
- %tmp83 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb84: ; preds = %bb84
- br i1 %c, label %bb91, label %bb94
-
-bb91: ; preds = %bb90
- %tmp93 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb94: ; preds = %bb94
- br i1 %c, label %bb101, label %bb104
-
-bb101: ; preds = %bb100
- %tmp103 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb104: ; preds = %bb104
- br i1 %c, label %bb119, label %bb123
-
-bb119: ; preds = %bb118
- %tmp122 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb47
-
-bb123: ; preds = %bb123
- br i1 %c, label %bb147, label %bb152
-
-bb147: ; preds = %bb146
- %tmp149 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- br label %bb150
-
-bb150: ; preds = %bb152, %bb147
- %.in = phi i64* [ %tmp184, %bb152 ], [ %tmp149, %bb147 ]
- br label %bb47
-
-bb152: ; preds = %bb146
- %tmp184 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
- call void undef()
- br label %bb150
-}
-
-; This used to cause an instcombine loop when the problem above was
-; addressed in a non-robust fashion.
-
-%type_1 = type {}
-%type_2 = type {}
-%type_3 = type {}
-
-define void @test_2(i1 %c) local_unnamed_addr {
-; CHECK-LABEL: @test_2(
-; CHECK-NEXT: entry:
-; CHECK-NEXT: br label [[WHILE_COND:%.*]]
-; CHECK: while.cond:
-; CHECK-NEXT: br label [[FOR_COND:%.*]]
-; CHECK: for.cond:
-; CHECK-NEXT: br i1 [[C:%.*]], label [[COND_TRUE133:%.*]], label [[COND_FALSE138:%.*]]
-; CHECK: cond.true133:
-; CHECK-NEXT: store %type_3* undef, %type_3** null, align 536870912
-; CHECK-NEXT: br label [[COND_END144:%.*]]
-; CHECK: cond.false138:
-; CHECK-NEXT: store %type_3* undef, %type_3** null, align 536870912
-; CHECK-NEXT: br label [[COND_END144]]
-; CHECK: cond.end144:
-; CHECK-NEXT: br label [[WHILE_COND]]
-;
-entry:
- br label %while.cond
-
-while.cond: ; preds = %cond.end144, %entry
- %link.0 = phi %type_2* [ undef, %entry ], [ %cond145, %cond.end144 ]
- %os115 = bitcast %type_2* %link.0 to %type_3*
- %ou116 = getelementptr inbounds %type_3, %type_3* %os115, i32 0
- %os1117 = bitcast %type_3* %ou116 to %type_1*
- br label %for.cond
-
-for.cond: ; preds = %while.cond
- br i1 %c, label %cond.true133, label %cond.false138
-
-cond.true133: ; preds = %sw.epilog
- %0 = load %type_2*, %type_2** undef, align 8
- br label %cond.end144
-
-cond.false138: ; preds = %sw.epilog
- %1 = load %type_2*, %type_2** undef, align 8
- br label %cond.end144
-
-cond.end144: ; preds = %cond.false138, %cond.true133
- %cond145 = phi %type_2* [ %0, %cond.true133 ], [ %1, %cond.false138 ]
- br label %while.cond
-}
