[llvm] fef3eee - [CostModel][X86] Convert AVX2 SRA by uniform constant to cost table

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-08-26T16:14:13+01:00
New Revision: fef3eeef480b05457c4045846e255d8167938b84

URL: https://github.com/llvm/llvm-project/commit/fef3eeef480b05457c4045846e255d8167938b84
DIFF: https://github.com/llvm/llvm-project/commit/fef3eeef480b05457c4045846e255d8167938b84.diff

LOG: [CostModel][X86] Convert AVX2 SRA by uniform constant to cost table

When adding cost kind support it will be easier to maintain these if we're not calculating on the fly

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86TargetTransformInfo.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index 90b563cd7d5c..dbe8b19b086f 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -807,6 +807,16 @@ InstructionCost X86TTIImpl::getArithmeticInstrCost(
         return LT.first * KindCost.value();
   }
 
+  static const CostKindTblEntry AVX2UniformShiftCostTable[] = {
+    { ISD::SRA,  MVT::v4i64,  {   4 } }, // 2*psrad + shuffle.
+  };
+
+  if (ST->hasAVX2() && Op2Info.isUniform())
+    if (const auto *Entry =
+            CostTableLookup(AVX2UniformShiftCostTable, ISD, LT.second))
+      if (auto KindCost = Entry->Cost[CostKind])
+        return LT.first * KindCost.value();
+
   static const CostKindTblEntry SSE2UniformShiftCostTable[] = {
     // Uniform splats are cheaper for the following instructions.
     { ISD::SHL,  MVT::v16i16, { 2+2 } }, // 2*psllw + split.
@@ -823,16 +833,11 @@ InstructionCost X86TTIImpl::getArithmeticInstrCost(
     { ISD::SRA,  MVT::v4i64,  { 8+2 } }, // 2*(2*psrad + shuffle) + split.
   };
 
-  if (ST->hasSSE2() && Op2Info.isUniform()) {
-    // Handle AVX2 uniform v4i64 ISD::SRA, it's not worth a table.
-    if (ISD == ISD::SRA && LT.second == MVT::v4i64 && ST->hasAVX2())
-      return LT.first * 4; // 2*psrad + shuffle.
-
+  if (ST->hasSSE2() && Op2Info.isUniform())
     if (const auto *Entry =
             CostTableLookup(SSE2UniformShiftCostTable, ISD, LT.second))
       if (auto KindCost = Entry->Cost[CostKind])
         return LT.first * KindCost.value();
-  }
 
   if (ISD == ISD::SHL && !Op2Info.isUniform() && Op2Info.isConstant()) {
     MVT VT = LT.second;