Vectorizer: Add support for loop reductions.

For example:

  for (i=0; i<n; i++)
   sum += A[i] +  B[i] + i;



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166351 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 123 insertions, 37 deletions

diff --git a/test/Transforms/LoopVectorize/gcc-examples.ll b/test/Transforms/LoopVectorize/gcc-examples.ll
index 4e9e6f940e..6fb1792b2c 100644
--- a/test/Transforms/LoopVectorize/gcc-examples.ll
+++ b/test/Transforms/LoopVectorize/gcc-examples.ll
@@ -202,9 +202,8 @@ define void @example8(i32 %x) nounwind uwtable ssp {
   ret void
 }
 
-; We can't vectorize because it has a reduction variable.
 ;CHECK: @example9
-;CHECK-NOT: <4 x i32>
+;CHECK: phi <4 x i32>
 ;CHECK: ret i32
 define i32 @example9() nounwind uwtable readonly ssp {
   br label %1
diff --git a/test/Transforms/LoopVectorize/increment.ll b/test/Transforms/LoopVectorize/increment.ll
deleted file mode 100644
index e944a9af92..0000000000
--- a/test/Transforms/LoopVectorize/increment.ll
+++ /dev/null
@@ -1,35 +0,0 @@
-; RUN: opt < %s  -loop-vectorize -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-macosx10.8.0"
-
-@a = common global [2048 x i32] zeroinitializer, align 16
-
-; This is the loop.
-;  for (i=0; i<n; i++){
-;    a[i] += i;
-;  }
-;CHECK: @inc
-;CHECK: load <4 x i32>
-;CHECK: add <4 x i32>
-;CHECK: store <4 x i32>
-;CHECK: ret void
-define void @inc(i32 %n) nounwind uwtable noinline ssp {
-  %1 = icmp sgt i32 %n, 0
-  br i1 %1, label %.lr.ph, label %._crit_edge
-
-.lr.ph:                                           ; preds = %0, %.lr.ph
-  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
-  %2 = getelementptr inbounds [2048 x i32]* @a, i64 0, i64 %indvars.iv
-  %3 = load i32* %2, align 4
-  %4 = trunc i64 %indvars.iv to i32
-  %5 = add nsw i32 %3, %4
-  store i32 %5, i32* %2, align 4
-  %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 %._crit_edge, label %.lr.ph
-
-._crit_edge:                                      ; preds = %.lr.ph, %0
-  ret void
-}
diff --git a/test/Transforms/LoopVectorize/reduction.ll b/test/Transforms/LoopVectorize/reduction.ll
new file mode 100644
index 0000000000..257f661a63
--- /dev/null
+++ b/test/Transforms/LoopVectorize/reduction.ll
@@ -0,0 +1,122 @@
+; RUN: opt < %s  -loop-vectorize -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-macosx10.8.0"
+
+;CHECK: @reduction_sum
+;CHECK: phi <4 x i32>
+;CHECK: load <4 x i32>
+;CHECK: add <4 x i32>
+;CHECK: ret i32
+define i32 @reduction_sum(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
+  %2 = getelementptr inbounds i32* %A, i64 %indvars.iv
+  %3 = load i32* %2, align 4
+  %4 = getelementptr inbounds i32* %B, i64 %indvars.iv
+  %5 = load i32* %4, align 4
+  %6 = trunc i64 %indvars.iv to i32
+  %7 = add i32 %sum.02, %6
+  %8 = add i32 %7, %3
+  %9 = add i32 %8, %5
+  %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 %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
+  ret i32 %sum.0.lcssa
+}
+
+;CHECK: @reduction_prod
+;CHECK: phi <4 x i32>
+;CHECK: load <4 x i32>
+;CHECK: mul <4 x i32>
+;CHECK: ret i32
+define i32 @reduction_prod(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %prod.02 = phi i32 [ %9, %.lr.ph ], [ 1, %0 ]
+  %2 = getelementptr inbounds i32* %A, i64 %indvars.iv
+  %3 = load i32* %2, align 4
+  %4 = getelementptr inbounds i32* %B, i64 %indvars.iv
+  %5 = load i32* %4, align 4
+  %6 = trunc i64 %indvars.iv to i32
+  %7 = mul i32 %prod.02, %6
+  %8 = mul i32 %7, %3
+  %9 = mul i32 %8, %5
+  %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 %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %prod.0.lcssa = phi i32 [ 1, %0 ], [ %9, %.lr.ph ]
+  ret i32 %prod.0.lcssa
+}
+
+;CHECK: @reduction_mix
+;CHECK: phi <4 x i32>
+;CHECK: load <4 x i32>
+;CHECK: mul <4 x i32>
+;CHECK: ret i32
+define i32 @reduction_mix(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
+  %2 = getelementptr inbounds i32* %A, i64 %indvars.iv
+  %3 = load i32* %2, align 4
+  %4 = getelementptr inbounds i32* %B, i64 %indvars.iv
+  %5 = load i32* %4, align 4
+  %6 = mul nsw i32 %5, %3
+  %7 = trunc i64 %indvars.iv to i32
+  %8 = add i32 %sum.02, %7
+  %9 = add i32 %8, %6
+  %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 %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
+  ret i32 %sum.0.lcssa
+}
+
+;CHECK: @reduction_bad
+;CHECK-NOT: <4 x i32>
+;CHECK: ret i32
+define i32 @reduction_bad(i32 %n, i32* noalias nocapture %A, i32* noalias nocapture %B) nounwind uwtable readonly noinline ssp {
+  %1 = icmp sgt i32 %n, 0
+  br i1 %1, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %0, %.lr.ph
+  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %0 ]
+  %sum.02 = phi i32 [ %9, %.lr.ph ], [ 0, %0 ]
+  %2 = getelementptr inbounds i32* %A, i64 %indvars.iv
+  %3 = load i32* %2, align 4
+  %4 = getelementptr inbounds i32* %B, i64 %indvars.iv
+  %5 = load i32* %4, align 4
+  %6 = trunc i64 %indvars.iv to i32
+  %7 = add i32 %3, %6
+  %8 = add i32 %7, %5
+  %9 = mul i32 %8, %sum.02
+  %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 %._crit_edge, label %.lr.ph
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %sum.0.lcssa = phi i32 [ 0, %0 ], [ %9, %.lr.ph ]
+  ret i32 %sum.0.lcssa
+}