Fix MachineLICM to actually visit inner loops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108001 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineLICM.cpp

@@ -199,9 +199,14 @@ FunctionPass *llvm::createMachineLICMPass(bool PreRegAlloc) {
 /// LoopIsOuterMostWithPredecessor - Test if the given loop is the outer-most
 /// loop that has a unique predecessor.
 static bool LoopIsOuterMostWithPredecessor(MachineLoop *CurLoop) {
+  // Check whether this loop even has a unique predecessor.
+  if (!CurLoop->getLoopPredecessor())
+    return false;
+  // Ok, now check to see if any of its outer loops do.
   for (MachineLoop *L = CurLoop->getParentLoop(); L; L = L->getParentLoop())
     if (L->getLoopPredecessor())
       return false;
+  // None of them did, so this is the outermost with a unique predecessor.
   return true;
 }
 
@@ -224,14 +229,17 @@ bool MachineLICM::runOnMachineFunction(MachineFunction &MF) {
   DT  = &getAnalysis<MachineDominatorTree>();
   AA  = &getAnalysis<AliasAnalysis>();
 
-  for (MachineLoopInfo::iterator I = MLI->begin(), E = MLI->end(); I != E; ++I){
+  SmallVector<MachineLoop *, 8> Worklist(MLI->begin(), MLI->end());
-    CurLoop = *I;
+  while (!Worklist.empty()) {
+    CurLoop = Worklist.pop_back_val();
     CurPreheader = 0;
 
     // If this is done before regalloc, only visit outer-most preheader-sporting
     // loops.
-    if (PreRegAlloc && !LoopIsOuterMostWithPredecessor(CurLoop))
+    if (PreRegAlloc && !LoopIsOuterMostWithPredecessor(CurLoop)) {
+      Worklist.append(CurLoop->begin(), CurLoop->end());
       continue;
+    }
 
     if (!PreRegAlloc)
       HoistRegionPostRA();

test/CodeGen/X86/licm-nested.ll

@@ -0,0 +1,89 @@
+; RUN: llc -march=x86-64 < %s -stats -info-output-file - | grep machine-licm | grep 2
+
+; MachineLICM should be able to hoist the symbolic addresses out of
+; the inner loops.
+
+@main.flags = internal global [8193 x i8] zeroinitializer, align 16 ; <[8193 x i8]*> [#uses=3]
+@.str = private constant [11 x i8] c"Count: %d\0A\00" ; <[11 x i8]*> [#uses=1]
+
+define i32 @main(i32 %argc, i8** nocapture %argv) nounwind ssp {
+entry:
+  %cmp = icmp eq i32 %argc, 2                     ; <i1> [#uses=1]
+  br i1 %cmp, label %while.cond.preheader, label %bb.nph53
+
+while.cond.preheader:                             ; preds = %entry
+  %arrayidx = getelementptr inbounds i8** %argv, i64 1 ; <i8**> [#uses=1]
+  %tmp2 = load i8** %arrayidx                     ; <i8*> [#uses=1]
+  %call = tail call i32 @atoi(i8* %tmp2) nounwind ; <i32> [#uses=2]
+  %tobool51 = icmp eq i32 %call, 0                ; <i1> [#uses=1]
+  br i1 %tobool51, label %while.end, label %bb.nph53
+
+while.cond.loopexit:                              ; preds = %for.inc35
+  %indvar.next77 = add i32 %indvar76, 1           ; <i32> [#uses=2]
+  %exitcond78 = icmp eq i32 %indvar.next77, %NUM.0.ph80 ; <i1> [#uses=1]
+  br i1 %exitcond78, label %while.end, label %bb.nph
+
+bb.nph53:                                         ; preds = %entry, %while.cond.preheader
+  %NUM.0.ph80 = phi i32 [ %call, %while.cond.preheader ], [ 17000, %entry ] ; <i32> [#uses=1]
+  br label %bb.nph
+
+bb.nph:                                           ; preds = %while.cond.loopexit, %bb.nph53
+  %indvar76 = phi i32 [ 0, %bb.nph53 ], [ %indvar.next77, %while.cond.loopexit ] ; <i32> [#uses=1]
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %bb.nph
+  %indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %for.body ] ; <i64> [#uses=2]
+  %tmp = add i64 %indvar, 2                       ; <i64> [#uses=1]
+  %arrayidx10 = getelementptr [8193 x i8]* @main.flags, i64 0, i64 %tmp ; <i8*> [#uses=1]
+  store i8 1, i8* %arrayidx10
+  %indvar.next = add i64 %indvar, 1               ; <i64> [#uses=2]
+  %exitcond = icmp eq i64 %indvar.next, 8191      ; <i1> [#uses=1]
+  br i1 %exitcond, label %for.body15, label %for.body
+
+for.body15:                                       ; preds = %for.body, %for.inc35
+  %indvar57 = phi i64 [ %indvar.next58, %for.inc35 ], [ 0, %for.body ] ; <i64> [#uses=4]
+  %count.248 = phi i32 [ %count.1, %for.inc35 ], [ 0, %for.body ] ; <i32> [#uses=2]
+  %tmp68 = add i64 %indvar57, 2                   ; <i64> [#uses=2]
+  %tmp70 = mul i64 %indvar57, 3                   ; <i64> [#uses=1]
+  %tmp71 = add i64 %tmp70, 6                      ; <i64> [#uses=1]
+  %tmp73 = shl i64 %indvar57, 1                   ; <i64> [#uses=1]
+  %add = add i64 %tmp73, 4                        ; <i64> [#uses=2]
+  %arrayidx17 = getelementptr [8193 x i8]* @main.flags, i64 0, i64 %tmp68 ; <i8*> [#uses=1]
+  %tmp18 = load i8* %arrayidx17                   ; <i8> [#uses=1]
+  %tobool19 = icmp eq i8 %tmp18, 0                ; <i1> [#uses=1]
+  br i1 %tobool19, label %for.inc35, label %if.then
+
+if.then:                                          ; preds = %for.body15
+  %cmp2443 = icmp slt i64 %add, 8193              ; <i1> [#uses=1]
+  br i1 %cmp2443, label %for.body25, label %for.end32
+
+for.body25:                                       ; preds = %if.then, %for.body25
+  %indvar55 = phi i64 [ %indvar.next56, %for.body25 ], [ 0, %if.then ] ; <i64> [#uses=2]
+  %tmp60 = mul i64 %tmp68, %indvar55              ; <i64> [#uses=2]
+  %tmp75 = add i64 %add, %tmp60                   ; <i64> [#uses=1]
+  %arrayidx27 = getelementptr [8193 x i8]* @main.flags, i64 0, i64 %tmp75 ; <i8*> [#uses=1]
+  store i8 0, i8* %arrayidx27
+  %add31 = add i64 %tmp71, %tmp60                 ; <i64> [#uses=1]
+  %cmp24 = icmp slt i64 %add31, 8193              ; <i1> [#uses=1]
+  %indvar.next56 = add i64 %indvar55, 1           ; <i64> [#uses=1]
+  br i1 %cmp24, label %for.body25, label %for.end32
+
+for.end32:                                        ; preds = %for.body25, %if.then
+  %inc34 = add nsw i32 %count.248, 1              ; <i32> [#uses=1]
+  br label %for.inc35
+
+for.inc35:                                        ; preds = %for.body15, %for.end32
+  %count.1 = phi i32 [ %inc34, %for.end32 ], [ %count.248, %for.body15 ] ; <i32> [#uses=2]
+  %indvar.next58 = add i64 %indvar57, 1           ; <i64> [#uses=2]
+  %exitcond67 = icmp eq i64 %indvar.next58, 8191  ; <i1> [#uses=1]
+  br i1 %exitcond67, label %while.cond.loopexit, label %for.body15
+
+while.end:                                        ; preds = %while.cond.loopexit, %while.cond.preheader
+  %count.0.lcssa = phi i32 [ 0, %while.cond.preheader ], [ %count.1, %while.cond.loopexit ] ; <i32> [#uses=1]
+  %call40 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([11 x i8]* @.str, i64 0, i64 0), i32 %count.0.lcssa) nounwind ; <i32> [#uses=0]
+  ret i32 0
+}
+
+declare i32 @atoi(i8* nocapture) nounwind readonly
+
+declare i32 @printf(i8* nocapture, ...) nounwind