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[ARM] sext of a load is free 

This teaches the cost model that the sext or zext of a load is going to be
free.

Differential Revision: https://reviews.llvm.org/D66006

llvm-svn: 368593
This commit is contained in:
David Green 2019-08-12 17:39:56 +00:00
parent 4c9c98f36b
commit 86876422ef
2 changed files with 35 additions and 14 deletions
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21
llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
View File

@ -167,6 +167,27 @@ int ARMTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
if (!SrcTy.isSimple() || !DstTy.isSimple()) if (!SrcTy.isSimple() || !DstTy.isSimple())
return BaseT::getCastInstrCost(Opcode, Dst, Src); return BaseT::getCastInstrCost(Opcode, Dst, Src);
// The extend of a load is free
if (I && isa<LoadInst>(I->getOperand(0))) {
static const TypeConversionCostTblEntry LoadConversionTbl[] = {
{ISD::SIGN_EXTEND, MVT::i32, MVT::i16, 0},
{ISD::ZERO_EXTEND, MVT::i32, MVT::i16, 0},
{ISD::SIGN_EXTEND, MVT::i32, MVT::i8, 0},
{ISD::ZERO_EXTEND, MVT::i32, MVT::i8, 0},
{ISD::SIGN_EXTEND, MVT::i16, MVT::i8, 0},
{ISD::ZERO_EXTEND, MVT::i16, MVT::i8, 0},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i32, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i32, 1},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i16, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i16, 1},
{ISD::SIGN_EXTEND, MVT::i64, MVT::i8, 1},
{ISD::ZERO_EXTEND, MVT::i64, MVT::i8, 1},
};
if (const auto *Entry = ConvertCostTableLookup(
LoadConversionTbl, ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT()))
return Entry->Cost;
}
// Some arithmetic, load and store operations have specific instructions // Some arithmetic, load and store operations have specific instructions
// to cast up/down their types automatically at no extra cost. // to cast up/down their types automatically at no extra cost.
// TODO: Get these tables to know at least what the related operations are. // TODO: Get these tables to know at least what the related operations are.

28
llvm/test/Analysis/CostModel/ARM/cast.ll
View File

@ -814,15 +814,15 @@ define i32 @load_extends() {
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i16 = load <2 x i16>, <2 x i16>* undef ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i16 = load <2 x i16>, <2 x i16>* undef
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv4i16 = load <4 x i16>, <4 x i16>* undef ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv4i16 = load <4 x i16>, <4 x i16>* undef
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i32 = load <2 x i32>, <2 x i32>* undef ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i32 = load <2 x i32>, <2 x i32>* undef
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r0 = sext i8 %loadi8 to i16 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r0 = sext i8 %loadi8 to i16
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r1 = zext i8 %loadi8 to i16 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r1 = zext i8 %loadi8 to i16
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r2 = sext i8 %loadi8 to i32 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r2 = sext i8 %loadi8 to i32
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r3 = zext i8 %loadi8 to i32 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r3 = zext i8 %loadi8 to i32
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r4 = sext i8 %loadi8 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r4 = sext i8 %loadi8 to i64
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r5 = zext i8 %loadi8 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r5 = zext i8 %loadi8 to i64
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r6 = sext i16 %loadi16 to i32 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r6 = sext i16 %loadi16 to i32
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r7 = zext i16 %loadi16 to i32 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r7 = zext i16 %loadi16 to i32
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %r8 = sext i16 %loadi16 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r8 = sext i16 %loadi16 to i64
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r9 = zext i16 %loadi16 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r9 = zext i16 %loadi16 to i64
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r10 = sext i32 %loadi32 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r10 = sext i32 %loadi32 to i64
; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r11 = zext i32 %loadi32 to i64 ; CHECK-NEON-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r11 = zext i32 %loadi32 to i64
@ -850,15 +850,15 @@ define i32 @load_extends() {
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i16 = load <2 x i16>, <2 x i16>* undef ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i16 = load <2 x i16>, <2 x i16>* undef
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv4i16 = load <4 x i16>, <4 x i16>* undef ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv4i16 = load <4 x i16>, <4 x i16>* undef
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i32 = load <2 x i32>, <2 x i32>* undef ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %loadv2i32 = load <2 x i32>, <2 x i32>* undef
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r0 = sext i8 %loadi8 to i16 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r0 = sext i8 %loadi8 to i16
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r1 = zext i8 %loadi8 to i16 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r1 = zext i8 %loadi8 to i16
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r2 = sext i8 %loadi8 to i32 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r2 = sext i8 %loadi8 to i32
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r3 = zext i8 %loadi8 to i32 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r3 = zext i8 %loadi8 to i32
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r4 = sext i8 %loadi8 to i64 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r4 = sext i8 %loadi8 to i64
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r5 = zext i8 %loadi8 to i64 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r5 = zext i8 %loadi8 to i64
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r6 = sext i16 %loadi16 to i32 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r6 = sext i16 %loadi16 to i32
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r7 = zext i16 %loadi16 to i32 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 0 for instruction: %r7 = zext i16 %loadi16 to i32
; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 2 for instruction: %r8 = sext i16 %loadi16 to i64 ; CHECK-MVE-NEXT: Cost Model: Found an estimated cost of 1 for instruction: %r8 = sext i16 %loadi16 to i64
; 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: %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: %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 1 for instruction: %r11 = zext i32 %loadi32 to i64