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ARM cost model: Increase the cost for vector casts that use the stack

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Increase the cost of v8/v16-i8 to v8/v16-i32 casts and truncates as the backend
currently lowers those using stack accesses.

This was responsible for a significant degradation on
MultiSource/Benchmarks/Trimaran/enc-pc1/enc-pc1
where we vectorize one loop to a vector factor of 16. After this patch we select
a vector factor of 4 which will generate reasonable code.

unsigned char cle[32];

void test(short c) {
  unsigned short compte;
  for (compte = 0; compte <= 31; compte++) {
    cle[compte] = cle[compte] ^ c;
  }
}

radar://13220512

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176898 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Arnold Schwaighofer 2013-03-12 21:19:22 +00:00
parent 9e999adb48
commit b6f4872d29
2 changed files with 22 additions and 0 deletions
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8
lib/Target/ARM/ARMTargetTransformInfo.cpp
View File

@ -194,6 +194,14 @@ unsigned ARMTTI::getCastInstrCost(unsigned Opcode, Type *Dst,
{ ISD::TRUNCATE, MVT::v4i32, MVT::v4i64, 0 },
{ ISD::TRUNCATE, MVT::v4i16, MVT::v4i32, 1 },
// Operations that we legalize using load/stores to the stack.
{ ISD::SIGN_EXTEND, MVT::v16i32, MVT::v16i8, 16*2 + 4*4 },
{ ISD::ZERO_EXTEND, MVT::v16i32, MVT::v16i8, 16*2 + 4*3 },
{ ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i8, 8*2 + 2*4 },
{ ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i8, 8*2 + 2*3 },
{ ISD::TRUNCATE, MVT::v16i8, MVT::v16i32, 4*1 + 16*2 + 2*1 },
{ ISD::TRUNCATE, MVT::v8i8, MVT::v8i32, 2*1 + 8*2 + 1 },
// Vector float <-> i32 conversions.
{ ISD::SINT_TO_FP, MVT::v4f32, MVT::v4i32, 1 },
{ ISD::UINT_TO_FP, MVT::v4f32, MVT::v4i32, 1 },

14
test/Analysis/CostModel/ARM/cast.ll
View File

@ -152,6 +152,20 @@ define i32 @casts() {
; CHECK: cost of 10 {{.*}} uitofp
%r69 = uitofp i64 undef to double
; Vector cast cost of instructions lowering the cast to the stack.
; CHECK: cost of 24 {{.*}} sext
%r70 = sext <8 x i8> undef to <8 x i32>
; CHECK: cost of 48 {{.*}} sext
%r71 = sext <16 x i8> undef to <16 x i32>
; CHECK: cost of 22 {{.*}} zext
%r72 = zext <8 x i8> undef to <8 x i32>
; CHECK: cost of 44 {{.*}} zext
%r73 = zext <16 x i8> undef to <16 x i32>
; CHECK: cost of 19 {{.*}} trunc
%r74 = trunc <8 x i32> undef to <8 x i8>
; CHECK: cost of 38 {{.*}} trunc
%r75 = trunc <16 x i32> undef to <16 x i8>
;CHECK: cost of 0 {{.*}} ret
ret i32 undef
}