[llvm] r348484 - Revert "[LoopSimplifyCFG] Delete dead in-loop blocks"
Ilya Biryukov via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 6 05:21:01 PST 2018
Author: ibiryukov
Date: Thu Dec 6 05:21:01 2018
New Revision: 348484
URL: http://llvm.org/viewvc/llvm-project?rev=348484&view=rev
Log:
Revert "[LoopSimplifyCFG] Delete dead in-loop blocks"
This reverts commit r348457.
The original commit causes clang to crash when doing an instrumented
build with a new pass manager. Reverting to unbreak our integrate.
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=348484&r1=348483&r2=348484&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Thu Dec 6 05:21:01 2018
@@ -46,8 +46,6 @@ static cl::opt<bool> EnableTermFolding("
STATISTIC(NumTerminatorsFolded,
"Number of terminators folded to unconditional branches");
-STATISTIC(NumLoopBlocksDeleted,
- "Number of loop blocks deleted");
/// If \p BB is a switch or a conditional branch, but only one of its successors
/// can be reached from this block in runtime, return this successor. Otherwise,
@@ -236,27 +234,6 @@ private:
"All blocks that stay in loop should be live!");
}
- /// Delete loop blocks that have become unreachable after folding. Make all
- /// relevant updates to DT and LI.
- void deleteDeadLoopBlocks() {
- DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
- if (MSSAU)
- MSSAU->removeBlocks(DeadLoopBlocks);
- for (auto *BB : DeadLoopBlocks) {
- assert(BB != L.getHeader() &&
- "Header of the current loop cannot be dead!");
- LLVM_DEBUG(dbgs() << "Deleting dead loop block " << BB->getName()
- << "\n");
- if (LI.isLoopHeader(BB)) {
- assert(LI.getLoopFor(BB) != &L && "Attempt to remove current loop!");
- LI.erase(LI.getLoopFor(BB));
- }
- LI.removeBlock(BB);
- DeleteDeadBlock(BB, &DTU);
- ++NumLoopBlocksDeleted;
- }
- }
-
/// Constant-fold terminators of blocks acculumated in FoldCandidates into the
/// unconditional branches.
void foldTerminators() {
@@ -341,6 +318,15 @@ public:
return false;
}
+ // TODO: Support deletion of dead loop blocks.
+ if (!DeadLoopBlocks.empty()) {
+ LLVM_DEBUG(dbgs() << "Give up constant terminator folding in loop "
+ << L.getHeader()->getName()
+ << ": we don't currently"
+ " support deletion of dead in-loop blocks.\n");
+ return false;
+ }
+
// TODO: Support dead loop exits.
if (!DeadExitBlocks.empty()) {
LLVM_DEBUG(dbgs() << "Give up constant terminator folding in loop "
@@ -351,8 +337,7 @@ public:
// TODO: Support blocks that are not dead, but also not in loop after the
// folding.
- if (BlocksInLoopAfterFolding.size() + DeadLoopBlocks.size() !=
- L.getNumBlocks()) {
+ if (BlocksInLoopAfterFolding.size() != L.getNumBlocks()) {
LLVM_DEBUG(
dbgs() << "Give up constant terminator folding in loop "
<< L.getHeader()->getName()
@@ -372,13 +357,6 @@ public:
// Make the actual transforms.
foldTerminators();
- if (!DeadLoopBlocks.empty()) {
- LLVM_DEBUG(dbgs() << "Deleting " << DeadLoopBlocks.size()
- << " dead blocks in loop " << L.getHeader()->getName()
- << "\n");
- deleteDeadLoopBlocks();
- }
-
#ifndef NDEBUG
// Make sure that we have preserved all data structures after the transform.
DT.verify();
Modified: llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll?rev=348484&r1=348483&r2=348484&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll (original)
+++ llvm/trunk/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll Thu Dec 6 05:21:01 2018
@@ -88,12 +88,18 @@ define i32 @dead_block_test_branch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[DEAD:%.*]]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -123,12 +129,22 @@ define i32 @dead_block_test_switch_loop(
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: switch i32 1, label [[DEAD:%.*]] [
+; CHECK-NEXT: i32 0, label [[DEAD]]
+; CHECK-NEXT: i32 1, label [[BACKEDGE]]
+; CHECK-NEXT: i32 2, label [[DEAD]]
+; CHECK-NEXT: ]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -159,12 +175,18 @@ define i32 @dead_block_propogate_test_br
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[DEAD:%.*]]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -197,12 +219,22 @@ define i32 @dead_block_propogate_test_sw
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: switch i32 1, label [[DEAD:%.*]] [
+; CHECK-NEXT: i32 0, label [[DEAD]]
+; CHECK-NEXT: i32 1, label [[BACKEDGE]]
+; CHECK-NEXT: i32 2, label [[DEAD]]
+; CHECK-NEXT: ]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -431,19 +463,32 @@ define i32 @dead_sub_loop_test_branch_lo
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[EXIT_A:%.*]] ]
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: br i1 true, label [[LIVE_PREHEADER:%.*]], label [[DEAD_PREHEADER:%.*]]
+; CHECK: live_preheader:
; CHECK-NEXT: br label [[LIVE_LOOP:%.*]]
; CHECK: live_loop:
-; CHECK-NEXT: [[A:%.*]] = phi i32 [ 0, [[HEADER]] ], [ [[A_INC:%.*]], [[LIVE_LOOP]] ]
+; CHECK-NEXT: [[A:%.*]] = phi i32 [ 0, [[LIVE_PREHEADER]] ], [ [[A_INC:%.*]], [[LIVE_LOOP]] ]
; CHECK-NEXT: [[A_INC]] = add i32 [[A]], 1
; CHECK-NEXT: [[CMP_A:%.*]] = icmp slt i32 [[A_INC]], [[END:%.*]]
-; CHECK-NEXT: br i1 [[CMP_A]], label [[LIVE_LOOP]], label [[EXIT_A]]
+; CHECK-NEXT: br i1 [[CMP_A]], label [[LIVE_LOOP]], label [[EXIT_A:%.*]]
; CHECK: exit.a:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: dead_preheader:
+; CHECK-NEXT: br label [[DEAD_LOOP:%.*]]
+; CHECK: dead_loop:
+; CHECK-NEXT: [[B:%.*]] = phi i32 [ 0, [[DEAD_PREHEADER]] ], [ [[B_INC:%.*]], [[DEAD_LOOP]] ]
+; CHECK-NEXT: [[B_INC]] = add i32 [[B]], 1
+; CHECK-NEXT: [[CMP_B:%.*]] = icmp slt i32 [[B_INC]], [[END]]
+; CHECK-NEXT: br i1 [[CMP_B]], label [[DEAD_LOOP]], label [[EXIT_B:%.*]]
+; CHECK: exit.b:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[EXIT_A]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -491,19 +536,36 @@ define i32 @dead_sub_loop_test_switch_lo
; CHECK-NEXT: preheader:
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[EXIT_A:%.*]] ]
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[PREHEADER:%.*]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: switch i32 1, label [[DEAD_PREHEADER:%.*]] [
+; CHECK-NEXT: i32 0, label [[DEAD_PREHEADER]]
+; CHECK-NEXT: i32 1, label [[LIVE_PREHEADER:%.*]]
+; CHECK-NEXT: i32 2, label [[DEAD_PREHEADER]]
+; CHECK-NEXT: ]
+; CHECK: live_preheader:
; CHECK-NEXT: br label [[LIVE_LOOP:%.*]]
; CHECK: live_loop:
-; CHECK-NEXT: [[A:%.*]] = phi i32 [ 0, [[HEADER]] ], [ [[A_INC:%.*]], [[LIVE_LOOP]] ]
+; CHECK-NEXT: [[A:%.*]] = phi i32 [ 0, [[LIVE_PREHEADER]] ], [ [[A_INC:%.*]], [[LIVE_LOOP]] ]
; CHECK-NEXT: [[A_INC]] = add i32 [[A]], 1
; CHECK-NEXT: [[CMP_A:%.*]] = icmp slt i32 [[A_INC]], [[END:%.*]]
-; CHECK-NEXT: br i1 [[CMP_A]], label [[LIVE_LOOP]], label [[EXIT_A]]
+; CHECK-NEXT: br i1 [[CMP_A]], label [[LIVE_LOOP]], label [[EXIT_A:%.*]]
; CHECK: exit.a:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: dead_preheader:
+; CHECK-NEXT: br label [[DEAD_LOOP:%.*]]
+; CHECK: dead_loop:
+; CHECK-NEXT: [[B:%.*]] = phi i32 [ 0, [[DEAD_PREHEADER]] ], [ [[B_INC:%.*]], [[DEAD_LOOP]] ]
+; CHECK-NEXT: [[B_INC]] = add i32 [[B]], 1
+; CHECK-NEXT: [[CMP_B:%.*]] = icmp slt i32 [[B_INC]], [[END]]
+; CHECK-NEXT: br i1 [[CMP_B]], label [[DEAD_LOOP]], label [[EXIT_B:%.*]]
+; CHECK: exit.b:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[EXIT:%.*]]
; CHECK: exit:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[EXIT_A]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: ret i32 [[I_INC_LCSSA]]
;
preheader:
@@ -836,12 +898,18 @@ define i32 @partial_sub_loop_test_branch
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[DEAD:%.*]]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[OUTER_BACKEDGE]]
; CHECK: outer_backedge:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: [[J_INC]] = add i32 [[J]], 1
; CHECK-NEXT: [[CMP_J:%.*]] = icmp slt i32 [[J_INC]], [[END]]
; CHECK-NEXT: br i1 [[CMP_J]], label [[OUTER_HEADER]], label [[EXIT:%.*]]
@@ -890,12 +958,22 @@ define i32 @partial_sub_loop_test_switch
; CHECK-NEXT: [[J:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[J_INC:%.*]], [[OUTER_BACKEDGE:%.*]] ]
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
-; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[HEADER]] ]
-; CHECK-NEXT: [[I_INC]] = add i32 [[I]], 1
+; CHECK-NEXT: [[I:%.*]] = phi i32 [ 0, [[OUTER_HEADER]] ], [ [[I_INC:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: switch i32 1, label [[DEAD:%.*]] [
+; CHECK-NEXT: i32 0, label [[DEAD]]
+; CHECK-NEXT: i32 1, label [[BACKEDGE]]
+; CHECK-NEXT: i32 2, label [[DEAD]]
+; CHECK-NEXT: ]
+; CHECK: dead:
+; CHECK-NEXT: [[I_2:%.*]] = add i32 [[I]], 1
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[I]], [[HEADER]] ], [ [[I_2]], [[DEAD]] ]
+; CHECK-NEXT: [[I_INC]] = add i32 [[I_1]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_INC]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP]], label [[HEADER]], label [[OUTER_BACKEDGE]]
; CHECK: outer_backedge:
-; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[HEADER]] ]
+; CHECK-NEXT: [[I_INC_LCSSA:%.*]] = phi i32 [ [[I_INC]], [[BACKEDGE]] ]
; CHECK-NEXT: [[J_INC]] = add i32 [[J]], 1
; CHECK-NEXT: [[CMP_J:%.*]] = icmp slt i32 [[J_INC]], [[END]]
; CHECK-NEXT: br i1 [[CMP_J]], label [[OUTER_HEADER]], label [[EXIT:%.*]]
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