Do not ignore iv uses outside the loop.

This one slipped through cracks very well.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56284 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/LoopIndexSplit.cpp

@@ -111,6 +111,10 @@ namespace {
     /// instruction then loop body is executed only for one iteration. In
     /// such case eliminate loop structure surrounding this loop body. For
     bool processOneIterationLoop(SplitInfo &SD);
+    
+    /// isOneIterationLoop - Return true if split condition is EQ and 
+    /// the IV is not used outside the loop.
+    bool isOneIterationLoop(ICmpInst *CI);
 
     void updateLoopBounds(ICmpInst *CI);
     /// updateLoopIterationSpace - Current loop body is covered by an AND
@@ -248,7 +252,7 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
         SI = SplitData.erase(Delete_SI);
       }
     }
-    else if (CI && CI->getPredicate() == ICmpInst::ICMP_EQ) {
+    else if (isOneIterationLoop(CI)) {
       Changed = processOneIterationLoop(SD);
       if (Changed) {
         ++NumIndexSplit;
@@ -276,6 +280,22 @@ bool LoopIndexSplit::runOnLoop(Loop *IncomingLoop, LPPassManager &LPM_Ref) {
   return Changed;
 }
 
+/// isOneIterationLoop - Return true if split condition is EQ and 
+/// the IV is not used outside the loop.
+bool LoopIndexSplit::isOneIterationLoop(ICmpInst *CI) {
+  if (!CI)
+    return false;
+  if (CI->getPredicate() != ICmpInst::ICMP_EQ)
+    return false;
+
+  Value *Incr = IndVar->getIncomingValueForBlock(L->getLoopLatch());
+  for (Value::use_iterator UI = Incr->use_begin(), E = Incr->use_end(); 
+       UI != E; ++UI)
+    if (!L->contains(cast<Instruction>(*UI)->getParent()))
+      return false;
+
+  return true;
+}
 /// Return true if V is a induction variable or induction variable's
 /// increment for loop L.
 void LoopIndexSplit::findIndVar(Value *V, Loop *L) {

test/Transforms/LoopIndexSplit/2008-05-19-IndVar.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as < %s | opt -loop-index-split | llvm-dis | grep tmp8 | count 3
-; count 3 = increment + phi + store
+; RUN: llvm-as < %s | opt -loop-index-split -stats -disable-output | not grep "loop-index-split"
 ;PR2294
 @g_2 = external global i16		; <i16*> [#uses=4]
 @g_5 = external global i32		; <i32*> [#uses=1]

test/Transforms/LoopIndexSplit/2008-09-17-IVUse.ll

@@ -0,0 +1,78 @@
+; RUN: llvm-as < %s | opt -loop-index-split -stats -disable-output | not grep "loop-index-split"
+; PR 2791
+@g_40 = common global i32 0		; <i32*> [#uses=1]
+@g_192 = common global i32 0		; <i32*> [#uses=2]
+@"\01LC" = internal constant [4 x i8] c"%d\0A\00"		; <[4 x i8]*> [#uses=1]
+
+define void @func_29() nounwind {
+entry:
+	%0 = load i32* @g_40, align 4		; <i32> [#uses=1]
+	%1 = icmp eq i32 %0, 0		; <i1> [#uses=1]
+	%g_192.promoted = load i32* @g_192		; <i32> [#uses=0]
+	br i1 %1, label %entry.split.us, label %entry.split
+
+entry.split.us:		; preds = %entry
+	br label %bb.us
+
+bb.us:		; preds = %bb5.us, %entry.split.us
+	%i.0.reg2mem.0.us = phi i32 [ 0, %entry.split.us ], [ %3, %bb5.us ]		; <i32> [#uses=2]
+	%2 = icmp eq i32 %i.0.reg2mem.0.us, 0		; <i1> [#uses=1]
+	br i1 %2, label %bb1.us, label %bb5.us
+
+bb5.us:		; preds = %bb1.us, %bb4.us, %bb.us
+	%iftmp.0.0.us = phi i32 [ 0, %bb4.us ], [ 1, %bb.us ], [ 1, %bb1.us ]		; <i32> [#uses=1]
+	%3 = add i32 %i.0.reg2mem.0.us, 1		; <i32> [#uses=3]
+	%4 = icmp ult i32 %3, 10		; <i1> [#uses=1]
+	br i1 %4, label %bb.us, label %bb8.us
+
+bb4.us:		; preds = %bb1.us
+	br label %bb5.us
+
+bb1.us:		; preds = %bb.us
+	br i1 true, label %bb4.us, label %bb5.us
+
+bb8.us:		; preds = %bb5.us
+	%iftmp.0.0.lcssa.us = phi i32 [ %iftmp.0.0.us, %bb5.us ]		; <i32> [#uses=1]
+	%.lcssa.us = phi i32 [ %3, %bb5.us ]		; <i32> [#uses=1]
+	br label %bb8.split
+
+entry.split:		; preds = %entry
+	br label %bb
+
+bb:		; preds = %bb5, %entry.split
+	%i.0.reg2mem.0 = phi i32 [ 0, %entry.split ], [ %6, %bb5 ]		; <i32> [#uses=2]
+	%5 = icmp eq i32 %i.0.reg2mem.0, 0		; <i1> [#uses=1]
+	br i1 %5, label %bb1, label %bb5
+
+bb1:		; preds = %bb
+	br i1 false, label %bb4, label %bb5
+
+bb4:		; preds = %bb1
+	br label %bb5
+
+bb5:		; preds = %bb1, %bb, %bb4
+	%iftmp.0.0 = phi i32 [ 0, %bb4 ], [ 1, %bb ], [ 1, %bb1 ]		; <i32> [#uses=1]
+	%6 = add i32 %i.0.reg2mem.0, 1		; <i32> [#uses=3]
+	%7 = icmp ult i32 %6, 10		; <i1> [#uses=1]
+	br i1 %7, label %bb, label %bb8
+
+bb8:		; preds = %bb5
+	%iftmp.0.0.lcssa = phi i32 [ %iftmp.0.0, %bb5 ]		; <i32> [#uses=1]
+	%.lcssa = phi i32 [ %6, %bb5 ]		; <i32> [#uses=1]
+	br label %bb8.split
+
+bb8.split:		; preds = %bb8.us, %bb8
+	%iftmp.0.0.lcssa.us-lcssa = phi i32 [ %iftmp.0.0.lcssa, %bb8 ], [ %iftmp.0.0.lcssa.us, %bb8.us ]		; <i32> [#uses=1]
+	%.lcssa.us-lcssa = phi i32 [ %.lcssa, %bb8 ], [ %.lcssa.us, %bb8.us ]		; <i32> [#uses=1]
+	store i32 %iftmp.0.0.lcssa.us-lcssa, i32* @g_192
+	%8 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @"\01LC", i32 0, i32 0), i32 %.lcssa.us-lcssa ) nounwind		; <i32> [#uses=0]
+	ret void
+}
+
+declare i32 @printf(i8*, ...) nounwind
+
+define i32 @main() nounwind {
+entry:
+	call void @func_29( ) nounwind
+	ret i32 0
+}

test/Transforms/LoopIndexSplit/OneIterLoop3-2007-08-17.ll

@@ -1,6 +1,5 @@
 ; Loop is elimianted. Save last value assignments, including induction variable.
-; RUN: llvm-as < %s | opt -loop-index-split -disable-output -stats |& \
-; RUN: grep "loop-index-split" | count 1
+; RUN: llvm-as < %s | opt -loop-index-split -disable-output -stats | not grep "loop-index-split"
 
 declare i32 @foo(i32)
 declare i32 @bar(i32, i32)