X86 cost model: Add cost for vectorized gather/scather

radar://14351991

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186189 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86TargetTransformInfo.cpp b/lib/Target/X86/X86TargetTransformInfo.cpp
index 68e1a6724366bc2397dc5e66d4fd85d43caa3680..3bbddadca88df17b4fb68768fdff1f9b83c58e38 100644 (file)
--- a/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -100,6 +100,8 @@ public:
                                    unsigned Alignment,
                                    unsigned AddressSpace) const;
 
+  virtual unsigned getAddressComputationCost(Type *PtrTy, bool IsComplex) const;
+
   /// @}
 };
 
@@ -598,3 +600,16 @@ unsigned X86TTI::getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
 
   return Cost;
 }
+
+unsigned X86TTI::getAddressComputationCost(Type *Ty, bool IsComplex) const {
+  // Address computations in vectorized code with non-consecutive addresses will
+  // likely result in more instructions compared to scalar code where the
+  // computation can more often be merged into the index mode. The resulting
+  // extra micro-ops can significantly decrease throughput.
+  unsigned NumVectorInstToHideOverhead = 10;
+
+  if (Ty->isVectorTy() && IsComplex)
+    return NumVectorInstToHideOverhead;
+
+  return TargetTransformInfo::getAddressComputationCost(Ty, IsComplex);
+}

diff --git a/test/Transforms/LoopVectorize/X86/gather-cost.ll b/test/Transforms/LoopVectorize/X86/gather-cost.ll
new file mode 100644 (file)
index 0000000..09363d6
--- /dev/null
+++ b/test/Transforms/LoopVectorize/X86/gather-cost.ll
@@ -0,0 +1,86 @@
+; RUN: opt -loop-vectorize -mtriple=x86_64-apple-macosx -S -mcpu=corei7-avx < %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"
+
+@kernel = global [512 x float] zeroinitializer, align 16
+@kernel2 = global [512 x float] zeroinitializer, align 16
+@kernel3 = global [512 x float] zeroinitializer, align 16
+@kernel4 = global [512 x float] zeroinitializer, align 16
+@src_data = global [1536 x float] zeroinitializer, align 16
+@r_ = global i8 0, align 1
+@g_ = global i8 0, align 1
+@b_ = global i8 0, align 1
+
+; We don't want to vectorize most loops containing gathers because they are
+; expensive. This function represents a point where vectorization starts to
+; become beneficial.
+; Make sure we are conservative and don't vectorize it.
+; CHECK-NOT: x float>
+
+define void @_Z4testmm(i64 %size, i64 %offset) {
+entry:
+  %cmp53 = icmp eq i64 %size, 0
+  br i1 %cmp53, label %for.end, label %for.body.lr.ph
+
+for.body.lr.ph:
+  br label %for.body
+
+for.body:
+  %r.057 = phi float [ 0.000000e+00, %for.body.lr.ph ], [ %add10, %for.body ]
+  %g.056 = phi float [ 0.000000e+00, %for.body.lr.ph ], [ %add20, %for.body ]
+  %v.055 = phi i64 [ 0, %for.body.lr.ph ], [ %inc, %for.body ]
+  %b.054 = phi float [ 0.000000e+00, %for.body.lr.ph ], [ %add30, %for.body ]
+  %add = add i64 %v.055, %offset
+  %mul = mul i64 %add, 3
+  %arrayidx = getelementptr inbounds [1536 x float]* @src_data, i64 0, i64 %mul
+  %0 = load float* %arrayidx, align 4
+  %arrayidx2 = getelementptr inbounds [512 x float]* @kernel, i64 0, i64 %v.055
+  %1 = load float* %arrayidx2, align 4
+  %mul3 = fmul fast float %0, %1
+  %arrayidx4 = getelementptr inbounds [512 x float]* @kernel2, i64 0, i64 %v.055
+  %2 = load float* %arrayidx4, align 4
+  %mul5 = fmul fast float %mul3, %2
+  %arrayidx6 = getelementptr inbounds [512 x float]* @kernel3, i64 0, i64 %v.055
+  %3 = load float* %arrayidx6, align 4
+  %mul7 = fmul fast float %mul5, %3
+  %arrayidx8 = getelementptr inbounds [512 x float]* @kernel4, i64 0, i64 %v.055
+  %4 = load float* %arrayidx8, align 4
+  %mul9 = fmul fast float %mul7, %4
+  %add10 = fadd fast float %r.057, %mul9
+  %arrayidx.sum = add i64 %mul, 1
+  %arrayidx11 = getelementptr inbounds [1536 x float]* @src_data, i64 0, i64 %arrayidx.sum
+  %5 = load float* %arrayidx11, align 4
+  %mul13 = fmul fast float %1, %5
+  %mul15 = fmul fast float %2, %mul13
+  %mul17 = fmul fast float %3, %mul15
+  %mul19 = fmul fast float %4, %mul17
+  %add20 = fadd fast float %g.056, %mul19
+  %arrayidx.sum52 = add i64 %mul, 2
+  %arrayidx21 = getelementptr inbounds [1536 x float]* @src_data, i64 0, i64 %arrayidx.sum52
+  %6 = load float* %arrayidx21, align 4
+  %mul23 = fmul fast float %1, %6
+  %mul25 = fmul fast float %2, %mul23
+  %mul27 = fmul fast float %3, %mul25
+  %mul29 = fmul fast float %4, %mul27
+  %add30 = fadd fast float %b.054, %mul29
+  %inc = add i64 %v.055, 1
+  %exitcond = icmp ne i64 %inc, %size
+  br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
+
+for.cond.for.end_crit_edge:
+  %add30.lcssa = phi float [ %add30, %for.body ]
+  %add20.lcssa = phi float [ %add20, %for.body ]
+  %add10.lcssa = phi float [ %add10, %for.body ]
+  %phitmp = fptoui float %add10.lcssa to i8
+  %phitmp60 = fptoui float %add20.lcssa to i8
+  %phitmp61 = fptoui float %add30.lcssa to i8
+  br label %for.end
+
+for.end:
+  %r.0.lcssa = phi i8 [ %phitmp, %for.cond.for.end_crit_edge ], [ 0, %entry ]
+  %g.0.lcssa = phi i8 [ %phitmp60, %for.cond.for.end_crit_edge ], [ 0, %entry ]
+  %b.0.lcssa = phi i8 [ %phitmp61, %for.cond.for.end_crit_edge ], [ 0, %entry ]
+  store i8 %r.0.lcssa, i8* @r_, align 1
+  store i8 %g.0.lcssa, i8* @g_, align 1
+  store i8 %b.0.lcssa, i8* @b_, align 1
+  ret void
+}