[CostModel][X86] Add ICMP Predicate specific costs

First step towards PR40376, this patch adds support for getCmpSelInstrCost to use the (optional) Instruction CmpInst predicate to indicate the type of integer comparison we're performing and alter the costs accordingly.

Differential Revision: https://reviews.llvm.org/D57013

llvm-svn: 351810

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -1650,6 +1650,47 @@ int X86TTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
   int ISD = TLI->InstructionOpcodeToISD(Opcode);
   assert(ISD && "Invalid opcode");
 
+  unsigned ExtraCost = 0;
+  if (I && (Opcode == Instruction::ICmp || Opcode == Instruction::FCmp)) {
+    // Some vector comparison predicates cost extra instructions.
+    if (MTy.isVector() &&
+        !((ST->hasXOP() && (!ST->hasAVX2() || MTy.is128BitVector())) ||
+          (ST->hasAVX512() && 32 <= MTy.getScalarSizeInBits()) ||
+          ST->hasBWI())) {
+      switch (cast<CmpInst>(I)->getPredicate()) {
+      case CmpInst::Predicate::ICMP_NE:
+        // xor(cmpeq(x,y),-1)
+        ExtraCost = 1;
+        break;
+      case CmpInst::Predicate::ICMP_SGE:
+      case CmpInst::Predicate::ICMP_SLE:
+        // xor(cmpgt(x,y),-1)
+        ExtraCost = 1;
+        break;
+      case CmpInst::Predicate::ICMP_ULT:
+      case CmpInst::Predicate::ICMP_UGT:
+        // cmpgt(xor(x,signbit),xor(y,signbit))
+        // xor(cmpeq(pmaxu(x,y),x),-1)
+        ExtraCost = 2;
+        break;
+      case CmpInst::Predicate::ICMP_ULE:
+      case CmpInst::Predicate::ICMP_UGE:
+        if ((ST->hasSSE41() && MTy.getScalarSizeInBits() == 32) ||
+            (ST->hasSSE2() && MTy.getScalarSizeInBits() < 32)) {
+          // cmpeq(psubus(x,y),0)
+          // cmpeq(pminu(x,y),x)
+          ExtraCost = 1;
+        } else {
+          // xor(cmpgt(xor(x,signbit),xor(y,signbit)),-1)
+          ExtraCost = 3;
+        }
+        break;
+      default:
+        break;
+      }
+    }
+  }
+
   static const CostTblEntry AVX512BWCostTbl[] = {
     { ISD::SETCC,   MVT::v32i16,  1 },
     { ISD::SETCC,   MVT::v64i8,   1 },
@@ -1738,35 +1779,35 @@ int X86TTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
 
   if (ST->hasBWI())
     if (const auto *Entry = CostTableLookup(AVX512BWCostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasAVX512())
     if (const auto *Entry = CostTableLookup(AVX512CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasAVX2())
     if (const auto *Entry = CostTableLookup(AVX2CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasAVX())
     if (const auto *Entry = CostTableLookup(AVX1CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasSSE42())
     if (const auto *Entry = CostTableLookup(SSE42CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasSSE41())
     if (const auto *Entry = CostTableLookup(SSE41CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasSSE2())
     if (const auto *Entry = CostTableLookup(SSE2CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   if (ST->hasSSE1())
     if (const auto *Entry = CostTableLookup(SSE1CostTbl, ISD, MTy))
-      return LT.first * Entry->Cost;
+      return LT.first * (ExtraCost + Entry->Cost);
 
   return BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, I);
 }