Do not simplifyLatch for loops where hoisting increments couldresult in extra live...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220872 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index ddb53926ff76cc229051c77cb5c7bc83d66d961a..afd2eca598e64dfbec20acd1482228936d01e75a 100644 (file)
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -194,8 +194,13 @@ static void RewriteUsesOfClonedInstructions(BasicBlock *OrigHeader,
 /// heuristics. We handle a single arithmetic instruction along with any type
 /// conversions.
 static bool shouldSpeculateInstrs(BasicBlock::iterator Begin,
 /// heuristics. We handle a single arithmetic instruction along with any type
 /// conversions.
 static bool shouldSpeculateInstrs(BasicBlock::iterator Begin,

-                                  BasicBlock::iterator End) {
+                                  BasicBlock::iterator End, Loop *L) {

   bool seenIncrement = false;
   bool seenIncrement = false;

+  bool MultiExitLoop = false;
+
+  if (!L->getExitingBlock())
+    MultiExitLoop = true;
+

   for (BasicBlock::iterator I = Begin; I != End; ++I) {
 
     if (!isSafeToSpeculativelyExecute(I))
   for (BasicBlock::iterator I = Begin; I != End; ++I) {
 
     if (!isSafeToSpeculativelyExecute(I))


@@ -219,11 +224,33 @@ static bool shouldSpeculateInstrs(BasicBlock::iterator Begin,
     case Instruction::Xor:
     case Instruction::Shl:
     case Instruction::LShr:
     case Instruction::Xor:
     case Instruction::Shl:
     case Instruction::LShr:

-    case Instruction::AShr:
+    case Instruction::AShr: {
+      Value *IVOpnd = nullptr;
+      if (isa<ConstantInt>(I->getOperand(0)))
+        IVOpnd = I->getOperand(1);
+
+      if (isa<ConstantInt>(I->getOperand(1))) {
+        if (IVOpnd)
+          return false;
+
+        IVOpnd = I->getOperand(0);
+      }
+
+      // If increment operand is used outside of the loop, this speculation
+      // could cause extra live range interference.
+      if (MultiExitLoop && IVOpnd) {
+        for (User *UseI : IVOpnd->users()) {
+          auto *UserInst = cast<Instruction>(UseI);
+          if (!L->contains(UserInst))
+            return false;
+        }
+      }
+

       if (seenIncrement)
         return false;
       seenIncrement = true;
       break;
       if (seenIncrement)
         return false;
       seenIncrement = true;
       break;

+    }

     case Instruction::Trunc:
     case Instruction::ZExt:
     case Instruction::SExt:
     case Instruction::Trunc:
     case Instruction::ZExt:
     case Instruction::SExt:


@@ -259,7 +286,7 @@ bool LoopRotate::simplifyLoopLatch(Loop *L) {
   if (!BI)
     return false;
 
   if (!BI)
     return false;
 

-  if (!shouldSpeculateInstrs(Latch->begin(), Jmp))
+  if (!shouldSpeculateInstrs(Latch->begin(), Jmp, L))

     return false;
 
   DEBUG(dbgs() << "Folding loop latch " << Latch->getName() << " into "
     return false;
 
   DEBUG(dbgs() << "Folding loop latch " << Latch->getName() << " into "

diff --git a/test/Transforms/LoopRotate/dbgvalue.ll b/test/Transforms/LoopRotate/dbgvalue.ll
index e90065609aa1b86664358f257178e3d636e7a16b..4da0776d6c8bf4a8894ed75b40c3b74af3a234e4 100644 (file)
--- a/test/Transforms/LoopRotate/dbgvalue.ll
+++ b/test/Transforms/LoopRotate/dbgvalue.ll
@@ -46,9 +46,9 @@ define void @FindFreeHorzSeg(i64 %startCol, i64 %row, i64* %rowStart) {
 ; CHECK-LABEL: define void @FindFreeHorzSeg(
 ; CHECK: %dec = add
 ; CHECK-NEXT: tail call void @llvm.dbg.value
 ; CHECK-LABEL: define void @FindFreeHorzSeg(
 ; CHECK: %dec = add
 ; CHECK-NEXT: tail call void @llvm.dbg.value

-; CHECK-NEXT: br i1 %tobool, label %for.cond, label %[[LOOP_EXIT:[^,]*]]
-; CHECK: [[LOOP_EXIT]]:
-; CHECK-NEXT: phi i64 [ %{{[^,]*}}, %{{[^,]*}} ]
+; CHECK: %cmp = icmp
+; CHECK: br i1 %cmp
+; CHECK: phi i64 [ %{{[^,]*}}, %{{[^,]*}} ]

 ; CHECK-NEXT: br label %for.end
 
 
 ; CHECK-NEXT: br label %for.end
 
 

diff --git a/test/Transforms/LoopRotate/simplifylatch.ll b/test/Transforms/LoopRotate/simplifylatch.ll
index d646cb9d6cb2608fdc15b3a747b7ce1ba2dd5880..62e5b1ae11d5f4bbf60f37aa027c6f1efd91a174 100644 (file)
--- a/test/Transforms/LoopRotate/simplifylatch.ll
+++ b/test/Transforms/LoopRotate/simplifylatch.ll
@@ -4,7 +4,7 @@
 @mode_table = global [4 x i32] zeroinitializer         ; <[4 x i32]*> [#uses=1]
 
 ; CHECK-LABEL: @f(
 @mode_table = global [4 x i32] zeroinitializer         ; <[4 x i32]*> [#uses=1]
 
 ; CHECK-LABEL: @f(

-; CHECK-NOT: bb4
+; CHECK-NOT: bb:

 define i8 @f() {
 entry:
        tail call i32 @fegetround( )            ; <i32>:0 [#uses=1]
 define i8 @f() {
 entry:
        tail call i32 @fegetround( )            ; <i32>:0 [#uses=1]