[llvm-commits] [llvm] r167035 - in /llvm/trunk: lib/Transforms/Vectorize/LoopVectorize.cpp test/Transforms/LoopVectorize/write-only.ll

[Nadav Rotem]

Author: nadav
Date: Tue Oct 30 13:36:45 2012
New Revision: 167035

URL: http://llvm.org/viewvc/llvm-project?rev=167035&view=rev
Log:
LoopVectorize: Add support for write-only loops when the write destination is a single pointer.
Speedup SciMark by 1%


Added:
    llvm/trunk/test/Transforms/LoopVectorize/write-only.ll
Modified:
    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp

Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=167035&r1=167034&r2=167035&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Tue Oct 30 13:36:45 2012
@@ -1348,6 +1348,13 @@
       Reads.push_back(Ptr);
   }
 
+  // If we write (or read-write) to a single destination and there are no
+  // other reads in this loop then is it safe to vectorize.
+  if (ReadWrites.size() == 1 && Reads.size() == 0) {
+    DEBUG(dbgs() << "LV: Found a write-only loop!\n");
+    return true;
+  }
+
   // Now that the pointers are in two lists (Reads and ReadWrites), we
   // can check that there are no conflicts between each of the writes and
   // between the writes to the reads.

Added: llvm/trunk/test/Transforms/LoopVectorize/write-only.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/write-only.ll?rev=167035&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/write-only.ll (added)
+++ llvm/trunk/test/Transforms/LoopVectorize/write-only.ll Tue Oct 30 13:36:45 2012
@@ -0,0 +1,26 @@
+; 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-macosx10.8.0"
+
+;CHECK: @read_mod_write_single_ptr
+;CHECK: load <4 x float>
+;CHECK: ret i32
+define i32 @read_mod_write_single_ptr(float* nocapture %a, i32 %n) nounwind uwtable 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 float* %a, i64 %indvars.iv
+  %3 = load float* %2, align 4
+  %4 = fmul float %3, 3.000000e+00
+  store float %4, float* %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 i32 undef
+}