LoopVectorize: Look for consecutive acces in GEPs with trailing zero indices

If we have a pointer to a single-element struct we can still build wide loads
and stores to it (if there is no padding).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193860 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 42 insertions, 0 deletions

diff --git a/test/Transforms/LoopVectorize/struct_access.ll b/test/Transforms/LoopVectorize/struct_access.ll
index 0cfaabe177..75beae82f1 100644
--- a/test/Transforms/LoopVectorize/struct_access.ll
+++ b/test/Transforms/LoopVectorize/struct_access.ll
@@ -44,3 +44,45 @@ for.end:                                          ; preds = %for.body, %entry
   %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
   ret i32 %sum.0.lcssa
 }
+
+%struct.lit = type { i32 }
+
+; Verify that we still vectorize the access if the struct has the same size as
+; the loaded element.
+; struct lit {
+;  int x;
+; };
+;
+;
+; int bar(struct lit *A, int n) {
+;
+;   int sum = 0;
+;   for (int i = 0; i < n; ++i)
+;     sum += A[i].x;
+;
+;   return sum;
+; }
+
+;CHECK-LABEL: @bar(
+;CHECK: load <4 x i32>
+;CHECK: ret
+define i32 @bar(%struct.lit* nocapture %A, i32 %n) nounwind uwtable readonly ssp {
+entry:
+  %cmp4 = icmp sgt i32 %n, 0
+  br i1 %cmp4, label %for.body, label %for.end
+
+for.body:                                         ; preds = %entry, %for.body
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
+  %sum.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+  %x = getelementptr inbounds %struct.lit* %A, i64 %indvars.iv, i32 0
+  %0 = load i32* %x, align 4
+  %add = add nsw i32 %0, %sum.05
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %entry
+  %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  ret i32 %sum.0.lcssa
+}