If all of the write objects are identified then we can vectorize the loop even if the read objects are unidentified.

PR14719.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171124 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 58 insertions, 1 deletions

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index d64295c7f7..7fb9bbada0 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1704,6 +1704,7 @@ bool LoopVectorizationLegality::canVectorizeMemory() {
 
   // Check that the read-writes do not conflict with other read-write
   // pointers.
+  bool AllWritesIdentified = true;
   for (I = ReadWrites.begin(), IE = ReadWrites.end(); I != IE; ++I) {
     GetUnderlyingObjects(*I, TempObjects, DL);
     for (ValueVector::iterator it=TempObjects.begin(), e=TempObjects.end();
@@ -1711,6 +1712,7 @@ bool LoopVectorizationLegality::canVectorizeMemory() {
       if (!isIdentifiedObject(*it)) {
         DEBUG(dbgs() << "LV: Found an unidentified write ptr:"<< **it <<"\n");
         NeedRTCheck = true;
+        AllWritesIdentified = false;
       }
       if (!WriteObjects.insert(*it)) {
         DEBUG(dbgs() << "LV: Found a possible write-write reorder:"
@@ -1726,7 +1728,9 @@ bool LoopVectorizationLegality::canVectorizeMemory() {
     GetUnderlyingObjects(*I, TempObjects, DL);
     for (ValueVector::iterator it=TempObjects.begin(), e=TempObjects.end();
          it != e; ++it) {
-      if (!isIdentifiedObject(*it)) {
+      // If all of the writes are identified then we don't care if the read
+      // pointer is identified or not.
+      if (!AllWritesIdentified && !isIdentifiedObject(*it)) {
         DEBUG(dbgs() << "LV: Found an unidentified read ptr:"<< **it <<"\n");
         NeedRTCheck = true;
       }
diff --git a/test/Transforms/LoopVectorize/calloc.ll b/test/Transforms/LoopVectorize/calloc.ll
new file mode 100644
index 0000000000..378c546988
--- /dev/null
+++ b/test/Transforms/LoopVectorize/calloc.ll
@@ -0,0 +1,53 @@
+; RUN: opt < %s  -loop-vectorize -force-vector-width=4 -dce -instcombine -licm -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+;CHECK: hexit
+;CHECK: zext <4 x i8>
+;CHECK: ret
+
+define noalias i8* @hexit(i8* nocapture %bytes, i64 %length) nounwind uwtable ssp {
+entry:
+  %shl = shl i64 %length, 1
+  %add28 = or i64 %shl, 1
+  %call = tail call i8* @calloc(i64 1, i64 %add28) nounwind
+  %cmp29 = icmp eq i64 %shl, 0
+  br i1 %cmp29, label %for.end, label %for.body.lr.ph
+
+for.body.lr.ph:                                   ; preds = %entry
+  %0 = shl i64 %length, 1
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %for.body.lr.ph
+  %i.030 = phi i64 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
+  %shr = lshr i64 %i.030, 1
+  %arrayidx = getelementptr inbounds i8* %bytes, i64 %shr
+  %1 = load i8* %arrayidx, align 1, !tbaa !0
+  %conv = zext i8 %1 to i32
+  %and = shl i64 %i.030, 2
+  %neg = and i64 %and, 4
+  %and3 = xor i64 %neg, 4
+  %sh_prom = trunc i64 %and3 to i32
+  %shl4 = shl i32 15, %sh_prom
+  %and5 = and i32 %conv, %shl4
+  %shr11 = lshr i32 %and5, %sh_prom
+  %conv13 = and i32 %shr11, 254
+  %cmp15 = icmp ugt i32 %conv13, 9
+  %cond = select i1 %cmp15, i32 87, i32 48
+  %add17 = add nsw i32 %cond, %shr11
+  %conv18 = trunc i32 %add17 to i8
+  %arrayidx19 = getelementptr inbounds i8* %call, i64 %i.030
+  store i8 %conv18, i8* %arrayidx19, align 1, !tbaa !0
+  %inc = add i64 %i.030, 1
+  %exitcond = icmp eq i64 %inc, %0
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %entry
+  ret i8* %call
+}
+
+declare noalias i8* @calloc(i64, i64) nounwind
+
+!0 = metadata !{metadata !"omnipotent char", metadata !1}
+!1 = metadata !{metadata !"Simple C/C++ TBAA"}