[LoopSimplifyCFG] Update MemorySSA after r353911.

Summary:
MemorySSA is not properly updated in LoopSimplifyCFG after recent changes. Use SplitBlock utility to resolve that and clear all updates once handleDeadExits is finished.
All updates that follow are removal of edges which are safe to handle via the removeEdge() API.
Also, deleting dead blocks is done correctly as is, i.e. delete from MemorySSA before updating the CFG and DT.

Reviewers: mkazantsev, rtereshin

Subscribers: sanjoy, jlebar, Prazek, george.burgess.iv, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58524

llvm-svn: 354613

llvm/lib/Transforms/Scalar/LoopSimplifyCFG.cpp

@@ -352,14 +352,9 @@ class ConstantTerminatorFoldingImpl {
     // Construct split preheader and the dummy switch to thread edges from it to
     // dead exits.
     BasicBlock *Preheader = L.getLoopPreheader();
-    BasicBlock *NewPreheader = Preheader->splitBasicBlock(
-        Preheader->getTerminator(),
-        Twine(Preheader->getName()).concat("-split"));
-    if (MSSAU)
-      MSSAU->removeEdge(Preheader, L.getHeader());
-    DTUpdates.push_back({DominatorTree::Delete, Preheader, L.getHeader()});
-    DTUpdates.push_back({DominatorTree::Insert, NewPreheader, L.getHeader()});
-    DTUpdates.push_back({DominatorTree::Insert, Preheader, NewPreheader});
+    BasicBlock *NewPreheader = llvm::SplitBlock(
+        Preheader, Preheader->getTerminator(), &DT, &LI, MSSAU);
+
     IRBuilder<> Builder(Preheader->getTerminator());
     SwitchInst *DummySwitch =
         Builder.CreateSwitch(Builder.getInt32(0), NewPreheader);
@@ -384,8 +379,6 @@ class ConstantTerminatorFoldingImpl {
 
     assert(L.getLoopPreheader() == NewPreheader && "Malformed CFG?");
     if (Loop *OuterLoop = LI.getLoopFor(Preheader)) {
-      OuterLoop->addBasicBlockToLoop(NewPreheader, LI);
-
       // When we break dead edges, the outer loop may become unreachable from
       // the current loop. We need to fix loop info accordingly. For this, we
       // find the most nested loop that still contains L and remove L from all
@@ -414,10 +407,21 @@ class ConstantTerminatorFoldingImpl {
         assert(FixLCSSALoop && "Should be a loop!");
         // We need all DT updates to be done before forming LCSSA.
         DTU.applyUpdates(DTUpdates);
+        if (MSSAU)
+          MSSAU->applyUpdates(DTUpdates, DT);
         DTUpdates.clear();
         formLCSSARecursively(*FixLCSSALoop, DT, &LI, &SE);
       }
     }
+
+    if (MSSAU) {
+      // Clear all updates now. Facilitates deletes that follow.
+      DTU.applyUpdates(DTUpdates);
+      MSSAU->applyUpdates(DTUpdates, DT);
+      DTUpdates.clear();
+      if (VerifyMemorySSA)
+        MSSAU->getMemorySSA()->verifyMemorySSA();
+    }
   }
 
   /// Delete loop blocks that have become unreachable after folding. Make all
@@ -589,6 +593,9 @@ class ConstantTerminatorFoldingImpl {
       DTUpdates.clear();
     }
 
+    if (MSSAU && VerifyMemorySSA)
+      MSSAU->getMemorySSA()->verifyMemorySSA();
+
 #ifndef NDEBUG
     // Make sure that we have preserved all data structures after the transform.
     assert(DT.verify() && "DT broken after transform!");

llvm/test/Transforms/LoopSimplifyCFG/constant-fold-branch.ll

@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; REQUIRES: asserts
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -debug-only=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)' -debug-only=loop-simplifycfg -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 -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa < %s | FileCheck %s
+; 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
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128-ni:1"
 
@@ -239,7 +239,7 @@ define i32 @dead_exit_test_branch_loop(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[DEAD:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -288,7 +288,7 @@ define i32 @dead_exit_test_switch_loop(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[DEAD:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -554,7 +554,7 @@ define i32 @inf_loop_test_branch_loop(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[EXIT:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -594,7 +594,7 @@ define i32 @inf_loop_test_switch_loop(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[EXIT:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -1197,7 +1197,7 @@ define i32 @full_sub_loop_test_branch_loop_inverse_2(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[OUTER_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -1258,7 +1258,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_2(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[OUTER_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -1320,7 +1320,7 @@ define i32 @full_sub_loop_test_branch_loop_inverse_3(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[OUTER_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -1380,7 +1380,7 @@ define i32 @full_sub_loop_test_switch_loop_inverse_3(i32 %end) {
 ; CHECK-NEXT:    switch i32 0, label [[PREHEADER_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[OUTER_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       preheader-split:
+; CHECK:       preheader.split:
 ; CHECK-NEXT:    br label [[HEADER:%.*]]
 ; CHECK:       header:
 ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ 0, [[PREHEADER_SPLIT]] ], [ [[I_INC:%.*]], [[HEADER]] ]
@@ -1443,7 +1443,7 @@ define i32 @exit_branch_from_inner_to_grandparent(i1 %cond1, i1 %cond2, i32 %N)
 ; CHECK-NEXT:    switch i32 0, label [[LOOP_2_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[LOOP_2_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       loop_2-split:
+; CHECK:       loop_2.split:
 ; CHECK-NEXT:    br label [[LOOP_3:%.*]]
 ; CHECK:       loop_3:
 ; CHECK-NEXT:    [[K:%.*]] = phi i32 [ 0, [[LOOP_2_SPLIT]] ], [ [[K_NEXT:%.*]], [[LOOP_3_BACKEDGE:%.*]] ]
@@ -1512,7 +1512,7 @@ define i32 @exit_switch_from_inner_to_grandparent(i1 %cond1, i1 %cond2, i32 %N)
 ; CHECK-NEXT:    switch i32 0, label [[LOOP_2_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[LOOP_2_BACKEDGE]]
 ; CHECK-NEXT:    ]
-; CHECK:       loop_2-split:
+; CHECK:       loop_2.split:
 ; CHECK-NEXT:    br label [[LOOP_3:%.*]]
 ; CHECK:       loop_3:
 ; CHECK-NEXT:    [[K:%.*]] = phi i32 [ 0, [[LOOP_2_SPLIT]] ], [ [[K_NEXT:%.*]], [[LOOP_3_BACKEDGE:%.*]] ]
@@ -2590,7 +2590,7 @@ define void @test_crash_01() {
 ; CHECK-NEXT:    switch i32 0, label [[BB2_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[BB19:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       bb2-split:
+; CHECK:       bb2.split:
 ; CHECK-NEXT:    br label [[BB3:%.*]]
 ; CHECK:       bb3:
 ; CHECK-NEXT:    switch i32 undef, label [[BB16:%.*]] [

llvm/test/Transforms/LoopSimplifyCFG/lcssa.ll

@@ -62,7 +62,7 @@ define void @test_01() {
 ; CHECK-NEXT:    switch i32 0, label [[FOR_COND_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[FOR_COND_LOOPEXIT]]
 ; CHECK-NEXT:    ]
-; CHECK:       for.cond-split:
+; CHECK:       for.cond.split:
 ; CHECK-NEXT:    [[INC41_LCSSA3_LCSSA:%.*]] = phi i16 [ [[INC41_LCSSA3]], [[FOR_COND]] ]
 ; CHECK-NEXT:    br label [[WHILE_COND:%.*]]
 ; CHECK:       while.cond:
@@ -96,7 +96,7 @@ define void @bar() {
 ; CHECK-NEXT:    switch i32 0, label [[BB_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[BB10:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       bb-split:
+; CHECK:       bb.split:
 ; CHECK-NEXT:    br label [[BB1:%.*]]
 ; CHECK:       bb1:
 ; CHECK-NEXT:    [[TMP:%.*]] = phi i32 [ [[TMP7:%.*]], [[BB6:%.*]] ], [ undef, [[BB_SPLIT]] ]
@@ -161,7 +161,7 @@ define void @memlcssa() {
 ; CHECK-NEXT:    switch i32 0, label [[ENTRY_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[DEFAULT_BB:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       entry-split:
+; CHECK:       entry.split:
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    call void @foo()

llvm/test/Transforms/LoopSimplifyCFG/live_block_marking.ll

@@ -1,16 +1,16 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; REQUIRES: asserts
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -indvars -loop-simplifycfg -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(indvars,simplify-cfg)' -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -indvars -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
+; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -indvars -loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
+; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(indvars,simplify-cfg)' -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
+; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -indvars -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
 
 define void @test(i1 %c) {
 ; CHECK-LABEL: @test(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    switch i32 0, label [[ENTRY_SPLIT:%.*]] [
 ; CHECK-NEXT:    i32 1, label [[DEAD_EXIT:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       entry-split:
+; CHECK:       entry.split:
 ; CHECK-NEXT:    br label [[OUTER:%.*]]
 ; CHECK:       outer:
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[TO_FOLD:%.*]], label [[LATCH:%.*]]

llvm/test/Transforms/LoopSimplifyCFG/mssa_update.ll

@@ -1,6 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; REQUIRES: asserts
-; XFAIL: *
 ; 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

llvm/test/Transforms/LoopSimplifyCFG/update_parents.ll

@@ -1,8 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; REQUIRES: asserts
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(simplify-cfg)' -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
-; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
+; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %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 2>&1 < %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 2>&1 < %s | FileCheck %s
 
 target triple = "x86_64-unknown-linux-gnu"
 
@@ -20,7 +20,7 @@ define void @test() {
 ; CHECK-NEXT:    i32 1, label [[BB1_LOOPEXIT:%.*]]
 ; CHECK-NEXT:    i32 2, label [[BB2_LOOPEXIT:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       bb2-split:
+; CHECK:       bb2.split:
 ; CHECK-NEXT:    br label [[BB3:%.*]]
 ; CHECK:       bb3:
 ; CHECK-NEXT:    br label [[BB3]]
@@ -61,7 +61,7 @@ define void @test_many_subloops(i1 %c) {
 ; CHECK-NEXT:    i32 1, label [[BB1_LOOPEXIT:%.*]]
 ; CHECK-NEXT:    i32 2, label [[BB2_LOOPEXIT:%.*]]
 ; CHECK-NEXT:    ]
-; CHECK:       bb2-split:
+; CHECK:       bb2.split:
 ; CHECK-NEXT:    br label [[BB3:%.*]]
 ; CHECK:       bb3:
 ; CHECK-NEXT:    br label [[BB3]]