This patch is to fix PR26529 caused by r259736.

IndVarSimplify assumes scAddRecExpr to be expanded in literal form instead of
canonical form by calling disableCanonicalMode after it creates SCEVExpander.
When CanonicalMode is disabled, SCEVExpander::expand should always return PHI
node for scAddRecExpr. r259736 broke the assumption.

The fix is to let SCEVExpander::expand skip the reuse Value logic if
CanonicalMode is false.

In addition, Besides IndVarSimplify, LSR pass also calls disableCanonicalMode
before doing rewrite. We can remove the original check of LSRMode in reuse
Value logic and use CanonicalMode instead.

llvm-svn: 260174

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 49cdcf7..45b0ada 100644 (file)
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1645,10 +1645,9 @@ Value *SCEVExpander::expand(const SCEV *S) {
   // Expand the expression into instructions.
   SetVector<Value *> *Set = SE.getSCEVValues(S);
   Value *V = nullptr;
-  // If the expansion is in LSRMode, and the SCEV contains any sub scAddRecExpr
-  // type SCEV, it will be expanded literally, to prevent LSR's transformed SCEV
-  // from being reverted.
-  if (!(LSRMode && SE.containsAddRecurrence(S))) {
+  // If the expansion is not in CanonicalMode, and the SCEV contains any
+  // sub scAddRecExpr type SCEV, it is required to expand the SCEV literally.
+  if (CanonicalMode || !SE.containsAddRecurrence(S)) {
     // If S is scConstant, it may be worse to reuse an existing Value.
     if (S->getSCEVType() != scConstant && Set) {
       // Choose a Value from the set which dominates the insertPt.

diff --git a/llvm/test/Analysis/ScalarEvolution/scev-canonical-mode.ll b/llvm/test/Analysis/ScalarEvolution/scev-canonical-mode.ll
new file mode 100644 (file)
index 0000000..0aa7ff0
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/scev-canonical-mode.ll
@@ -0,0 +1,32 @@
+; PR26529: Check the assumption of IndVarSimplify to do SCEV expansion in literal mode
+; instead of CanonicalMode is properly maintained in SCEVExpander::expand.
+; RUN: opt -indvars < %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: norecurse nounwind uwtable
+define void @ehF() #0 {
+entry:
+  br i1 undef, label %if.then.i, label %hup.exit
+
+if.then.i:                                        ; preds = %entry
+  br i1 undef, label %for.body.lr.ph.i, label %hup.exit
+
+for.body.lr.ph.i:                                 ; preds = %if.then.i
+  br label %for.body.i
+
+for.body.i:                                       ; preds = %for.body.i, %for.body.lr.ph.i
+  %i.03.i = phi i32 [ 0, %for.body.lr.ph.i ], [ %inc.i, %for.body.i ]
+  %k.02.i = phi i32 [ 1, %for.body.lr.ph.i ], [ %inc5.i, %for.body.i ]
+  %inc.i = add nsw i32 %i.03.i, 1
+  %idxprom.i = sext i32 %i.03.i to i64
+  %idxprom2.i = sext i32 %k.02.i to i64
+  %inc5.i = add nsw i32 %k.02.i, 1
+  br i1 false, label %for.body.i, label %hup.exit
+
+hup.exit:                                         ; preds = %for.body.i, %if.then.i, %entry
+  ret void
+}
+
+attributes #0 = { norecurse nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }