The cost of splitting a large vector instruction is not being taken into account by the getUserCost function. This was leading to some loops being over unrolled. The cost of a vector instruction is now being multiplied by the cost of the type legalization. This will return a more accurate cost.

Committing on behalf on Brad Nemanich (brad.nemanich@ibm.com)

Differential Revision: https://reviews.llvm.org/D38961

llvm-svn: 316174

3 files changed, 87 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index d3295a9d22e..52c5b688d35 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -189,6 +189,17 @@ int PPCTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
   return PPCTTIImpl::getIntImmCost(Imm, Ty);
 }
 
+unsigned PPCTTIImpl::getUserCost(const User *U,
+                                 ArrayRef<const Value *> Operands) {
+  if (U->getType()->isVectorTy()) {
+    // Instructions that need to be split should cost more.
+    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, U->getType());
+    return LT.first * BaseT::getUserCost(U, Operands);
+  }
+  
+  return BaseT::getUserCost(U, Operands);
+}
+
 void PPCTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                          TTI::UnrollingPreferences &UP) {
   if (ST->getDarwinDirective() == PPC::DIR_A2) {
diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
index b6b93ba9379..60dea0b0226 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.h
@@ -51,6 +51,8 @@ public:
   int getIntImmCost(Intrinsic::ID IID, unsigned Idx, const APInt &Imm,
                     Type *Ty);
 
+  unsigned getUserCost(const User *U, ArrayRef<const Value *> Operands);
+
   TTI::PopcntSupportKind getPopcntSupport(unsigned TyWidth);
   void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                TTI::UnrollingPreferences &UP);
diff --git a/llvm/test/Transforms/LoopUnroll/PowerPC/p8-unrolling-legalize-vectors.ll b/llvm/test/Transforms/LoopUnroll/PowerPC/p8-unrolling-legalize-vectors.ll
new file mode 100644
index 00000000000..27998230abe
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/PowerPC/p8-unrolling-legalize-vectors.ll
@@ -0,0 +1,74 @@
+; RUN: opt < %s -S -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 -loop-unroll | FileCheck %s
+; RUN: opt < %s -S -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr9 -loop-unroll | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le-unknown-linux-gnu"
+
+; Function Attrs: norecurse nounwind
+define i8* @f(i8* returned %s, i32 zeroext %x, i32 signext %k) local_unnamed_addr #0 {
+entry:
+  %cmp10 = icmp sgt i32 %k, 0
+  br i1 %cmp10, label %for.body.lr.ph, label %for.end
+
+for.body.lr.ph:                                   ; preds = %entry
+  %wide.trip.count = zext i32 %k to i64
+  %min.iters.check = icmp ult i32 %k, 16
+  br i1 %min.iters.check, label %for.body.preheader, label %vector.ph
+
+vector.ph:                                        ; preds = %for.body.lr.ph
+  %n.vec = and i64 %wide.trip.count, 4294967280
+  %broadcast.splatinsert = insertelement <16 x i32> undef, i32 %x, i32 0
+  %broadcast.splat = shufflevector <16 x i32> %broadcast.splatinsert, <16 x i32> undef, <16 x i32> zeroinitializer
+  br label %vector.body
+
+vector.body:                                      ; preds = %vector.body, %vector.ph
+  %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
+  %vec.ind12 = phi <16 x i32> [ <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7, i32 8, i32 9, i32 10, i32 11, i32 12, i32 13, i32 14, i32 15>, %vector.ph ], [ %vec.ind.next13, %vector.body ]
+  %0 = shl <16 x i32> <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>, %vec.ind12
+  %1 = and <16 x i32> %0, %broadcast.splat
+  %2 = icmp eq <16 x i32> %1, zeroinitializer
+  %3 = select <16 x i1> %2, <16 x i8> <i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48, i8 48>, <16 x i8> <i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49, i8 49>
+  %4 = getelementptr inbounds i8, i8* %s, i64 %index
+  %5 = bitcast i8* %4 to <16 x i8>*
+  store <16 x i8> %3, <16 x i8>* %5, align 1
+  %index.next = add i64 %index, 16
+  %vec.ind.next13 = add <16 x i32> %vec.ind12, <i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16, i32 16>
+  %6 = icmp eq i64 %index.next, %n.vec
+  br i1 %6, label %middle.block, label %vector.body
+
+middle.block:                                     ; preds = %vector.body
+  %cmp.n = icmp eq i64 %n.vec, %wide.trip.count
+  br i1 %cmp.n, label %for.end, label %for.body.preheader
+
+for.body.preheader:                               ; preds = %middle.block, %for.body.lr.ph
+  %indvars.iv.ph = phi i64 [ 0, %for.body.lr.ph ], [ %n.vec, %middle.block ]
+  br label %for.body
+
+for.body:                                         ; preds = %for.body.preheader, %for.body
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ %indvars.iv.ph, %for.body.preheader ]
+  %7 = trunc i64 %indvars.iv to i32
+  %shl = shl i32 1, %7
+  %and = and i32 %shl, %x
+  %tobool = icmp eq i32 %and, 0
+  %conv = select i1 %tobool, i8 48, i8 49
+  %arrayidx = getelementptr inbounds i8, i8* %s, i64 %indvars.iv
+  store i8 %conv, i8* %arrayidx, align 1
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, %wide.trip.count
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %middle.block, %entry
+  %idxprom1 = sext i32 %k to i64
+  %arrayidx2 = getelementptr inbounds i8, i8* %s, i64 %idxprom1
+  store i8 0, i8* %arrayidx2, align 1
+  ret i8* %s
+}
+
+
+; CHECK-LABEL: vector.body
+; CHECK:      shl
+; CHECK-NEXT: and
+; CHECK: shl
+; CHECK-NEXT: and
+; CHECK: label %vector.body
+