SLPVectorizer: Only vectorize intrinsics whose operands are widened e…

…qually

The vectorizer only knows how to vectorize intrinics by widening all operands by
the same factor.

Patch by Tyler Nowicki!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205855 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/Utils/VectorUtils.h

@@ -0,0 +1,54 @@
+//===- llvm/Transforms/Utils/VectorUtils.h - Vector utilities -*- C++ -*-=====//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines some vectorizer utilities.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_VECTORUTILS_H
+#define LLVM_TRANSFORMS_UTILS_VECTORUTILS_H
+
+namespace llvm {
+
+/// \brief Identify if the intrinsic is trivially vectorizable.
+///
+/// This method returns true if the intrinsic's argument types are all
+/// scalars for the scalar form of the intrinsic and all vectors for
+/// the vector form of the intrinsic.
+static inline bool isTriviallyVectorizable(Intrinsic::ID ID) {
+  switch (ID) {
+  case Intrinsic::sqrt:
+  case Intrinsic::sin:
+  case Intrinsic::cos:
+  case Intrinsic::exp:
+  case Intrinsic::exp2:
+  case Intrinsic::log:
+  case Intrinsic::log10:
+  case Intrinsic::log2:
+  case Intrinsic::fabs:
+  case Intrinsic::copysign:
+  case Intrinsic::floor:
+  case Intrinsic::ceil:
+  case Intrinsic::trunc:
+  case Intrinsic::rint:
+  case Intrinsic::nearbyint:
+  case Intrinsic::round:
+  case Intrinsic::ctpop:
+  case Intrinsic::pow:
+  case Intrinsic::fma:
+  case Intrinsic::fmuladd:
+    return true;
+  default:
+    return false;
+  }
+}
+
+} // llvm namespace
+
+#endif

lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -91,6 +91,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/VectorUtils.h"
 #include <algorithm>
 #include <map>
 
@@ -2266,32 +2267,12 @@ static Intrinsic::ID
 getIntrinsicIDForCall(CallInst *CI, const TargetLibraryInfo *TLI) {
   // If we have an intrinsic call, check if it is trivially vectorizable.
   if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
-    switch (II->getIntrinsicID()) {
-    case Intrinsic::sqrt:
-    case Intrinsic::sin:
-    case Intrinsic::cos:
-    case Intrinsic::exp:
-    case Intrinsic::exp2:
-    case Intrinsic::log:
-    case Intrinsic::log10:
-    case Intrinsic::log2:
-    case Intrinsic::fabs:
-    case Intrinsic::copysign:
-    case Intrinsic::floor:
-    case Intrinsic::ceil:
-    case Intrinsic::trunc:
-    case Intrinsic::rint:
-    case Intrinsic::nearbyint:
-    case Intrinsic::round:
-    case Intrinsic::pow:
-    case Intrinsic::fma:
-    case Intrinsic::fmuladd:
-    case Intrinsic::lifetime_start:
-    case Intrinsic::lifetime_end:
-      return II->getIntrinsicID();
-    default:
+    Intrinsic::ID ID = II->getIntrinsicID();
+    if (isTriviallyVectorizable(ID) || ID == Intrinsic::lifetime_start ||
+        ID == Intrinsic::lifetime_end)
+      return ID;
+    else
       return Intrinsic::not_intrinsic;
-    }
   }
 
   if (!TLI)

lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -41,6 +41,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/VectorUtils.h"
 #include <algorithm>
 #include <map>
 
@@ -949,7 +950,9 @@ void BoUpSLP::buildTree_rec(ArrayRef<Value *> VL, unsigned Depth) {
     case Instruction::Call: {
       // Check if the calls are all to the same vectorizable intrinsic.
       IntrinsicInst *II = dyn_cast<IntrinsicInst>(VL[0]);
-      if (II==NULL) {
+      Intrinsic::ID ID = II ? II->getIntrinsicID() : Intrinsic::not_intrinsic;
+
+      if (!isTriviallyVectorizable(ID)) {
         newTreeEntry(VL, false);
         DEBUG(dbgs() << "SLP: Non-vectorizable call.\n");
         return;

test/Transforms/SLPVectorizer/X86/non-vectorizable-intrinsic.ll

@@ -0,0 +1,36 @@
+; RUN: opt < %s -slp-vectorizer -o - -S -slp-threshold=-1000
+
+target datalayout = "e-p:32:32-i64:64-v16:16-v32:32-n16:32:64"
+target triple = "nvptx--nvidiacl"
+
+; CTLZ cannot be vectorized currently because the second argument is a scalar
+; for both the scalar and vector forms of the intrinsic. In the future it
+; should be possible to vectorize such functions.
+; Test causes an assert if LLVM tries to vectorize CTLZ.
+
+define <2 x i8> @cltz_test(<2 x i8> %x) #0 {
+entry:
+  %0 = extractelement <2 x i8> %x, i32 0
+  %call.i = call i8 @llvm.ctlz.i8(i8 %0, i1 false)
+  %vecinit = insertelement <2 x i8> undef, i8 %call.i, i32 0
+  %1 = extractelement <2 x i8> %x, i32 1
+  %call.i4 = call i8 @llvm.ctlz.i8(i8 %1, i1 false)
+  %vecinit2 = insertelement <2 x i8> %vecinit, i8 %call.i4, i32 1
+  ret <2 x i8> %vecinit2
+}
+
+define <2 x i8> @cltz_test2(<2 x i8> %x) #1 {
+entry:
+  %0 = extractelement <2 x i8> %x, i32 0
+  %1 = extractelement <2 x i8> %x, i32 1
+  %call.i = call i8 @llvm.ctlz.i8(i8 %0, i1 false)
+  %call.i4 = call i8 @llvm.ctlz.i8(i8 %1, i1 false)
+  %vecinit = insertelement <2 x i8> undef, i8 %call.i, i32 0
+  %vecinit2 = insertelement <2 x i8> %vecinit, i8 %call.i4, i32 1
+  ret <2 x i8> %vecinit2
+}
+
+declare i8 @llvm.ctlz.i8(i8, i1) #3
+
+attributes #0 = { alwaysinline nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }