[LoopInterchange] Skip zext instructions when looking for induction var.

Summary:
SimplifyIndVar may introduce zext instructions to widen arguments of the
loop exit check. They should not prevent us from splitting the loop at
the induction variable, but maybe the check should be more conservative,
e.g. making sure it only extends arguments used by a comparison?

Reviewers: karthikthecool, mcrosier, mzolotukhin

Reviewed By: mcrosier

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D34879

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311783 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopInterchange.cpp b/lib/Transforms/Scalar/LoopInterchange.cpp
index 2f05ec2b329b0551c8f640e24247a218383e41ee..1559e80f06f66ccd32ac1623c2974ed329700dfb 100644 (file)
--- a/lib/Transforms/Scalar/LoopInterchange.cpp
+++ b/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -908,7 +908,8 @@ bool LoopInterchangeLegality::currentLimitations() {
 
   bool FoundInduction = false;
   for (const Instruction &I : reverse(*InnerLoopLatch)) {
-    if (isa<BranchInst>(I) || isa<CmpInst>(I) || isa<TruncInst>(I))
+    if (isa<BranchInst>(I) || isa<CmpInst>(I) || isa<TruncInst>(I) ||
+        isa<ZExtInst>(I))
       continue;
 
     // We found an instruction. If this is not induction variable then it is not

diff --git a/test/Transforms/LoopInterchange/interchange-insts-between-indvar.ll b/test/Transforms/LoopInterchange/interchange-insts-between-indvar.ll
new file mode 100644 (file)
index 0000000..b609490
--- /dev/null
+++ b/test/Transforms/LoopInterchange/interchange-insts-between-indvar.ll
@@ -0,0 +1,80 @@
+; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
+
+@A10 = local_unnamed_addr global [3 x [3 x i32]] zeroinitializer, align 16
+
+;; Test to make sure we can handle zext intructions introduced by
+;; IndVarSimplify.
+;;
+;;  for (int i = 0; i < 2; ++i)
+;;    for(int j = 0; j < n; ++j) {
+;;      A[j][i] = i;
+;;    }
+
+@A11 = local_unnamed_addr global [3 x [3 x i32]] zeroinitializer, align 16
+
+define void @interchange_11(i32 %n) {
+entry:
+  br label %for.cond1.preheader
+
+for.cond.loopexit:                                ; preds = %for.body4
+  %exitcond28 = icmp ne i64 %indvars.iv.next27, 2
+  br i1 %exitcond28, label %for.cond1.preheader, label %for.cond.cleanup
+
+for.cond1.preheader:                              ; preds = %for.cond.loopexit, %entry
+  %indvars.iv26 = phi i64 [ 0, %entry ], [ %indvars.iv.next27, %for.cond.loopexit ]
+  %indvars.iv.next27 = add nuw nsw i64 %indvars.iv26, 1
+  br label %for.body4
+
+for.cond.cleanup:                                 ; preds = %for.cond.loopexit
+  ret void
+
+for.body4:                                        ; preds = %for.body4, %for.cond1.preheader
+  %indvars.iv = phi i64 [ 0, %for.cond1.preheader ], [ %indvars.iv.next, %for.body4 ]
+  %arrayidx6 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv26
+  %tmp = trunc i64 %indvars.iv26 to i32
+  store i32 %tmp, i32* %arrayidx6, align 4
+  %arrayidx10 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv.next27
+  %tmp1 = trunc i64 %indvars.iv to i32
+  store i32 %tmp1, i32* %arrayidx10, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %n.wide = zext i32 %n to i64
+  %exitcond = icmp ne i64 %indvars.iv.next, %n.wide
+  br i1 %exitcond, label %for.body4, label %for.cond.loopexit
+}
+
+; CHECK-LABEL: @interchange_11
+; CHECK: entry:
+; CHECK:   br label %for.body4.preheader
+
+; CHECK: for.cond1.preheader.preheader:
+; CHECK:   br label %for.cond1.preheader
+
+; CHECK: for.cond.loopexit:
+; CHECK:   %exitcond28 = icmp ne i64 %indvars.iv.next27, 2
+; CHECK:   br i1 %exitcond28, label %for.cond1.preheader, label %for.body4.split
+
+; CHECK: for.cond1.preheader:
+; CHECK:   %indvars.iv26 = phi i64 [ %indvars.iv.next27, %for.cond.loopexit ], [ 0, %for.cond1.preheader.preheader ]
+; CHECK:   %indvars.iv.next27 = add nuw nsw i64 %indvars.iv26, 1
+; CHECK:   br label %for.body4.split1
+
+; CHECK: for.body4.preheader:
+; CHECK:   br label %for.body4
+
+; CHECK: for.cond.cleanup:
+; CHECK:   ret void
+
+; CHECK: for.body4:
+; CHECK:   %indvars.iv = phi i64 [ %indvars.iv.next, %for.body4.split ], [ 0, %for.body4.preheader ]
+; CHECK:   br label %for.cond1.preheader.preheader
+
+; CHECK: for.body4.split1:
+; CHECK:   %arrayidx6 = getelementptr inbounds [3 x [3 x i32]], [3 x [3 x i32]]* @A10, i64 0, i64 %indvars.iv, i64 %indvars.iv26
+; CHECK:   %tmp = trunc i64 %indvars.iv26 to i32
+; CHECK:   store i32 %tmp, i32* %arrayidx6, align 4
+; CHECK:   br label %for.cond.loopexit
+
+; CHECK: for.body4.split:
+; CHECK:   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK:   %exitcond = icmp ne i64 %indvars.iv.next, %n.wide
+; CHECK:   br i1 %exitcond, label %for.body4, label %for.cond.cleanup