[PATCH] D78547: [TTI] getUserCost to return getCastInstrCost

[Sam Parker via Phabricator via llvm-commits]

samparker created this revision.
samparker added reviewers: spatel, RKSimon, craig.topper.
Herald added a project: LLVM.

If the generic cost model, based on DataLayout, says that a cast is free then return zero. Otherwise we now return the cost provided by getCastInstrCost.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78547

Files:
  llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
  llvm/test/Analysis/CostModel/X86/size-cost.ll


Index: llvm/test/Analysis/CostModel/X86/size-cost.ll
===================================================================
--- llvm/test/Analysis/CostModel/X86/size-cost.ll
+++ llvm/test/Analysis/CostModel/X86/size-cost.ll
@@ -30,7 +30,7 @@
 
 define i64 @bitcast_f64_i64(double %x) {
 ; CHECK-LABEL: 'bitcast_f64_i64'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %r = bitcast double %x to i64
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %r = bitcast double %x to i64
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret i64 %r
 ;
   %r = bitcast double %x to i64
@@ -39,7 +39,7 @@
 
 define double @bitcast_i64_f64(i64 %x) {
 ; CHECK-LABEL: 'bitcast_i64_f64'
-; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %r = bitcast i64 %x to double
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %r = bitcast i64 %x to double
 ; CHECK-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: ret double %r
 ;
   %r = bitcast i64 %x to double
Index: llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -846,14 +846,11 @@
     case Instruction::IntToPtr:
     case Instruction::PtrToInt:
     case Instruction::Trunc:
-      if (getCastInstrCost(Opcode, Ty, OpTy, I) == TTI::TCC_Free ||
-          TargetTTI->getCastInstrCost(Opcode, Ty, OpTy, I) == TTI::TCC_Free)
-        return TTI::TCC_Free;
-      break;
     case Instruction::BitCast:
-      if (getCastInstrCost(Opcode, Ty, OpTy, I) == TTI::TCC_Free)
-        return TTI::TCC_Free;
-      break;
+      // Check if the operation is free according to the datalayout.
+      if (getCastInstrCost(Opcode, Ty, OpTy, I) == 0)
+        return 0;
+      return TargetTTI->getCastInstrCost(Opcode, Ty, OpTy, I);
     case Instruction::FPExt:
     case Instruction::SExt:
     case Instruction::ZExt:


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