[MemorySSA & LoopPassManager] Update MemorySSA in formDedicatedExitBlocks.

MemorySSA is now updated when forming dedicated exit blocks.
Resolves PR40037.

llvm-svn: 354623

4 files changed, 20 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index db7da8edd51..befdfc5cef0 100644
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -267,7 +267,8 @@ static void rewritePHINodesForExitAndUnswitchedBlocks(BasicBlock &ExitBB,
 /// loops reachable and need to move the current loop up the loop nest or even
 /// to an entirely separate nest.
 static void hoistLoopToNewParent(Loop &L, BasicBlock &Preheader,
-                                 DominatorTree &DT, LoopInfo &LI) {
+                                 DominatorTree &DT, LoopInfo &LI,
+                                 MemorySSAUpdater *MSSAU) {
   // If the loop is already at the top level, we can't hoist it anywhere.
   Loop *OldParentL = L.getParentLoop();
   if (!OldParentL)
@@ -328,7 +329,8 @@ static void hoistLoopToNewParent(Loop &L, BasicBlock &Preheader,
     // unswitching it is possible to get new non-dedicated exits out of parent
     // loop so let's conservatively form dedicated exit blocks and figure out
     // if we can optimize later.
-    formDedicatedExitBlocks(OldContainingL, &DT, &LI, /*PreserveLCSSA*/ true);
+    formDedicatedExitBlocks(OldContainingL, &DT, &LI, MSSAU,
+                            /*PreserveLCSSA*/ true);
   }
 }
 
@@ -535,7 +537,10 @@ static bool unswitchTrivialBranch(Loop &L, BranchInst &BI, DominatorTree &DT,
   // If this was full unswitching, we may have changed the nesting relationship
   // for this loop so hoist it to its correct parent if needed.
   if (FullUnswitch)
-    hoistLoopToNewParent(L, *NewPH, DT, LI);
+    hoistLoopToNewParent(L, *NewPH, DT, LI, MSSAU);
+
+  if (MSSAU && VerifyMemorySSA)
+    MSSAU->getMemorySSA()->verifyMemorySSA();
 
   LLVM_DEBUG(dbgs() << "    done: unswitching trivial branch...\n");
   ++NumTrivial;
@@ -804,7 +809,10 @@ static bool unswitchTrivialSwitch(Loop &L, SwitchInst &SI, DominatorTree &DT,
 
   // We may have changed the nesting relationship for this loop so hoist it to
   // its correct parent if needed.
-  hoistLoopToNewParent(L, *NewPH, DT, LI);
+  hoistLoopToNewParent(L, *NewPH, DT, LI, MSSAU);
+
+  if (MSSAU && VerifyMemorySSA)
+    MSSAU->getMemorySSA()->verifyMemorySSA();
 
   ++NumTrivial;
   ++NumSwitches;
@@ -2239,7 +2247,7 @@ static void unswitchNontrivialInvariants(
     // introduced new, non-dedicated exits. At least try to re-form dedicated
     // exits for these loops. This may fail if they couldn't have dedicated
     // exits to start with.
-    formDedicatedExitBlocks(&UpdateL, &DT, &LI, /*PreserveLCSSA*/ true);
+    formDedicatedExitBlocks(&UpdateL, &DT, &LI, MSSAU, /*PreserveLCSSA*/ true);
   };
 
   // For non-child cloned loops and hoisted loops, we just need to update LCSSA
diff --git a/llvm/lib/Transforms/Utils/LoopSimplify.cpp b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
index ca29f6787e2..c347b5e26e3 100644
--- a/llvm/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/llvm/lib/Transforms/Utils/LoopSimplify.cpp
@@ -317,7 +317,7 @@ static Loop *separateNestedLoop(Loop *L, BasicBlock *Preheader,
 
   // Split edges to exit blocks from the inner loop, if they emerged in the
   // process of separating the outer one.
-  formDedicatedExitBlocks(L, DT, LI, PreserveLCSSA);
+  formDedicatedExitBlocks(L, DT, LI, nullptr, PreserveLCSSA);
 
   if (PreserveLCSSA) {
     // Fix LCSSA form for L. Some values, which previously were only used inside
@@ -530,7 +530,7 @@ ReprocessLoop:
   // predecessors that are inside of the loop.  This check guarantees that the
   // loop preheader/header will dominate the exit blocks.  If the exit block has
   // predecessors from outside of the loop, split the edge now.
-  if (formDedicatedExitBlocks(L, DT, LI, PreserveLCSSA))
+  if (formDedicatedExitBlocks(L, DT, LI, nullptr, PreserveLCSSA))
     Changed = true;
 
   // If the header has more than two predecessors at this point (from the
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
index a9d41945b27..2f1a759870c 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
@@ -938,11 +938,11 @@ bool llvm::UnrollRuntimeLoopRemainder(Loop *L, unsigned Count,
   if (OtherExits.size() > 0) {
     // Generate dedicated exit blocks for the original loop, to preserve
     // LoopSimplifyForm.
-    formDedicatedExitBlocks(L, DT, LI, PreserveLCSSA);
+    formDedicatedExitBlocks(L, DT, LI, nullptr, PreserveLCSSA);
     // Generate dedicated exit blocks for the remainder loop if one exists, to
     // preserve LoopSimplifyForm.
     if (remainderLoop)
-      formDedicatedExitBlocks(remainderLoop, DT, LI, PreserveLCSSA);
+      formDedicatedExitBlocks(remainderLoop, DT, LI, nullptr, PreserveLCSSA);
   }
 
   auto UnrollResult = LoopUnrollResult::Unmodified;
diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 5539ff12e4a..44f47bf71ca 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
+#include "llvm/Analysis/MemorySSAUpdater.h"
 #include "llvm/Analysis/MustExecute.h"
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
@@ -46,6 +47,7 @@ using namespace llvm::PatternMatch;
 static const char *LLVMLoopDisableNonforced = "llvm.loop.disable_nonforced";
 
 bool llvm::formDedicatedExitBlocks(Loop *L, DominatorTree *DT, LoopInfo *LI,
+                                   MemorySSAUpdater *MSSAU,
                                    bool PreserveLCSSA) {
   bool Changed = false;
 
@@ -81,7 +83,7 @@ bool llvm::formDedicatedExitBlocks(Loop *L, DominatorTree *DT, LoopInfo *LI,
       return false;
 
     auto *NewExitBB = SplitBlockPredecessors(
-        BB, InLoopPredecessors, ".loopexit", DT, LI, nullptr, PreserveLCSSA);
+        BB, InLoopPredecessors, ".loopexit", DT, LI, MSSAU, PreserveLCSSA);
 
     if (!NewExitBB)
       LLVM_DEBUG(