[LoopSimplifyCFG] Pay respect to LCSSA when removing dead blocks
Utility function that we use for blocks deletion always unconditionally removes
one-input Phis. In LoopSimplifyCFG, it can lead to breach of LCSSA form.
This patch alters this function to keep them if needed.
Differential Revision: https://reviews.llvm.org/D57231
Reviewed By: fedor.sergeev
llvm-svn: 353803
diff --git a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index 01d770c..896f9dd 100644
--- a/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -418,7 +418,7 @@
LI.removeBlock(BB);
}
- DetatchDeadBlocks(DeadLoopBlocks, &DTUpdates);
+ DetatchDeadBlocks(DeadLoopBlocks, &DTUpdates, /*KeepOneInputPHIs*/true);
DTU.applyUpdates(DTUpdates);
DTUpdates.clear();
for (auto *BB : DeadLoopBlocks)
diff --git a/llvm/test/Transforms/LoopSimplifyCFG/lcssa.ll b/llvm/test/Transforms/LoopSimplifyCFG/lcssa.ll
index e5609b9..8281f36 100644
--- a/llvm/test/Transforms/LoopSimplifyCFG/lcssa.ll
+++ b/llvm/test/Transforms/LoopSimplifyCFG/lcssa.ll
@@ -1,6 +1,4 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; XFAIL: *
-; REQUIRES: asserts
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(simplify-cfg)' -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
@@ -93,8 +91,31 @@
}
define void @bar() {
-
-; CHECK-LABEL: @bar
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: switch i32 0, label [[BB_SPLIT:%.*]] [
+; CHECK-NEXT: i32 1, label [[BB10:%.*]]
+; CHECK-NEXT: ]
+; CHECK: bb-split:
+; CHECK-NEXT: br label [[BB1:%.*]]
+; CHECK: bb1:
+; CHECK-NEXT: [[TMP:%.*]] = phi i32 [ [[TMP7:%.*]], [[BB6:%.*]] ], [ undef, [[BB_SPLIT]] ]
+; CHECK-NEXT: switch i32 undef, label [[BB5:%.*]] [
+; CHECK-NEXT: i32 0, label [[BB6]]
+; CHECK-NEXT: i32 1, label [[BB8:%.*]]
+; CHECK-NEXT: ]
+; CHECK: bb5:
+; CHECK-NEXT: ret void
+; CHECK: bb6:
+; CHECK-NEXT: [[TMP7]] = add i32 undef, 123
+; CHECK-NEXT: br label [[BB1]]
+; CHECK: bb8:
+; CHECK-NEXT: [[TMP9:%.*]] = phi i32 [ [[TMP]], [[BB1]] ]
+; CHECK-NEXT: [[USE:%.*]] = add i32 [[TMP9]], 1
+; CHECK-NEXT: ret void
+; CHECK: bb10:
+; CHECK-NEXT: ret void
+;
bb:
br label %bb1
@@ -105,8 +126,8 @@
bb2: ; preds = %bb1
switch i32 undef, label %bb10 [
- i32 0, label %bb3
- i32 1, label %bb8
+ i32 0, label %bb3
+ i32 1, label %bb8
]
bb3: ; preds = %bb2
@@ -114,8 +135,8 @@
bb4: ; preds = %bb1
switch i32 undef, label %bb5 [
- i32 0, label %bb6
- i32 1, label %bb8
+ i32 0, label %bb6
+ i32 1, label %bb8
]
bb5: ; preds = %bb4
