[PATCH] llvm.noalias - don't prevent loop vectorization

[hfinkel at anl.gov]

Hi chandlerc, reames, aschwaighofer,

This is part of the series started by D9375, and teaches the loop vectorizer enough about llvm.noalias that it should not interfere with vectorization when it happens to appear inside a loop we might otherwise vectorize.

http://reviews.llvm.org/D9382

Files:
  include/llvm/Analysis/TargetTransformInfoImpl.h
  include/llvm/Transforms/Utils/VectorUtils.h
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/noalias.ll

Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -149,6 +149,7 @@
     case Intrinsic::invariant_end:
     case Intrinsic::lifetime_start:
     case Intrinsic::lifetime_end:
+    case Intrinsic::noalias:
     case Intrinsic::objectsize:
     case Intrinsic::ptr_annotation:
     case Intrinsic::var_annotation:
Index: include/llvm/Transforms/Utils/VectorUtils.h
===================================================================
--- include/llvm/Transforms/Utils/VectorUtils.h
+++ include/llvm/Transforms/Utils/VectorUtils.h
@@ -101,7 +101,8 @@
   if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
     Intrinsic::ID ID = II->getIntrinsicID();
     if (isTriviallyVectorizable(ID) || ID == Intrinsic::lifetime_start ||
-        ID == Intrinsic::lifetime_end || ID == Intrinsic::assume)
+        ID == Intrinsic::lifetime_end || ID == Intrinsic::assume ||
+        ID == Intrinsic::noalias)
       return ID;
     else
       return Intrinsic::not_intrinsic;
Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3144,20 +3144,21 @@
       Module *M = BB->getParent()->getParent();
       CallInst *CI = cast<CallInst>(it);
 
+      Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI);
+      if (ID &&
+          (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end ||
+           ID == Intrinsic::lifetime_start || ID == Intrinsic::noalias)) {
+        scalarizeInstruction(it);
+        break;
+      }
+
       StringRef FnName = CI->getCalledFunction()->getName();
       Function *F = CI->getCalledFunction();
       Type *RetTy = ToVectorTy(CI->getType(), VF);
       SmallVector<Type *, 4> Tys;
       for (unsigned i = 0, ie = CI->getNumArgOperands(); i != ie; ++i)
         Tys.push_back(ToVectorTy(CI->getArgOperand(i)->getType(), VF));
 
-      Intrinsic::ID ID = getIntrinsicIDForCall(CI, TLI);
-      if (ID &&
-          (ID == Intrinsic::assume || ID == Intrinsic::lifetime_end ||
-           ID == Intrinsic::lifetime_start)) {
-        scalarizeInstruction(it);
-        break;
-      }
       // The flag shows whether we use Intrinsic or a usual Call for vectorized
       // version of the instruction.
       // Is it beneficial to perform intrinsic call compared to lib call?
Index: test/Transforms/LoopVectorize/noalias.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoopVectorize/noalias.ll
@@ -0,0 +1,34 @@
+; RUN: opt -S -loop-vectorize -force-vector-width=2 -force-vector-interleave=1 < %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"
+
+; Make sure we can vectorize loops which contain lifetime markers.
+
+; CHECK-LABEL: @test(
+; CHECK: @llvm.noalias.p0i32
+; CHECK: store <2 x i32>
+
+define void @test(i32 *%d) {
+entry:
+  br label %for.body
+
+for.body:
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %d2 = call i32* @llvm.noalias.p0i32(i32* %d, metadata !1)
+  %arrayidx = getelementptr inbounds i32, i32* %d2, i64 %indvars.iv
+  %v1 = load i32, i32* %arrayidx, align 8
+  store i32 100, i32* %arrayidx, align 8
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp ne i32 %lftr.wideiv, 128
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.end:
+  ret void
+}
+
+declare i32* @llvm.noalias.p0i32(i32*, metadata) nounwind
+
+!0 = !{!0, !"some domain"}
+!1 = !{!1, !0, !"some scope"}
+

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