[llvm] r369118 - [ARM] MVE sext of a load is free

[David Green via llvm-commits]

Author: dmgreen
Date: Fri Aug 16 08:13:37 2019
New Revision: 369118

URL: http://llvm.org/viewvc/llvm-project?rev=369118&view=rev
Log:
[ARM] MVE sext of a load is free

MVE also has some sext of loads, which will be free just as scalar
instructions are.

Differential Revision: https://reviews.llvm.org/D66008

Modified:
    llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp
    llvm/trunk/test/Analysis/CostModel/ARM/cast.ll

Modified: llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp?rev=369118&r1=369117&r2=369118&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp Fri Aug 16 08:13:37 2019
@@ -186,6 +186,21 @@ int ARMTTIImpl::getCastInstrCost(unsigne
     if (const auto *Entry = ConvertCostTableLookup(
             LoadConversionTbl, ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
       return Entry->Cost;
+
+    static const TypeConversionCostTblEntry MVELoadConversionTbl[] = {
+        {ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 0},
+        {ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 0},
+        {ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i8, 0},
+        {ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i8, 0},
+        {ISD::SIGN_EXTEND, MVT::v8i16, MVT::v8i8, 0},
+        {ISD::ZERO_EXTEND, MVT::v8i16, MVT::v8i8, 0},
+    };
+    if (SrcTy.isVector() && ST->hasMVEIntegerOps()) {
+      if (const auto *Entry =
+              ConvertCostTableLookup(MVELoadConversionTbl, ISD,
+                                     DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
+        return Entry->Cost;
+    }
   }
 
   // Some arithmetic, load and store operations have specific instructions

Modified: llvm/trunk/test/Analysis/CostModel/ARM/cast.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CostModel/ARM/cast.ll?rev=369118&r1=369117&r2=369118&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/CostModel/ARM/cast.ll (original)
+++ llvm/trunk/test/Analysis/CostModel/ARM/cast.ll Fri Aug 16 08:13:37 2019
@@ -862,14 +862,14 @@ define i32 @load_extends() {
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %r9 = zext i16 %loadi16 to i64
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %r10 = sext i32 %loadi32 to i64
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 1 for instruction: %r11 = zext i32 %loadi32 to i64
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v0 = sext <8 x i8> %loadv8i8 to <8 x i16>
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v1 = zext <8 x i8> %loadv8i8 to <8 x i16>
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v2 = sext <4 x i8> %loadv4i8 to <4 x i32>
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v3 = zext <4 x i8> %loadv4i8 to <4 x i32>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v0 = sext <8 x i8> %loadv8i8 to <8 x i16>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v1 = zext <8 x i8> %loadv8i8 to <8 x i16>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v2 = sext <4 x i8> %loadv4i8 to <4 x i32>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v3 = zext <4 x i8> %loadv4i8 to <4 x i32>
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v4 = sext <2 x i8> %loadv2i8 to <2 x i64>
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v5 = zext <2 x i8> %loadv2i8 to <2 x i64>
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v6 = sext <4 x i16> %loadv4i16 to <4 x i32>
-; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v7 = zext <4 x i16> %loadv4i16 to <4 x i32>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v6 = sext <4 x i16> %loadv4i16 to <4 x i32>
+; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: %v7 = zext <4 x i16> %loadv4i16 to <4 x i32>
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v8 = sext <2 x i16> %loadv2i16 to <2 x i64>
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %v9 = zext <2 x i16> %loadv2i16 to <2 x i64>
 ; CHECK-MVE-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %v10 = sext <2 x i32> %loadv2i32 to <2 x i64>