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[IR] Make {extract,insert}element accept an index of any integer type.

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Given the following C code llvm currently generates suboptimal code for
x86-64:

__m128 bss4( const __m128 *ptr, size_t i, size_t j )
{
    float f = ptr[i][j];
    return (__m128) { f, f, f, f };
}

=================================================

define <4 x float> @_Z4bss4PKDv4_fmm(<4 x float>* nocapture readonly %ptr, i64 %i, i64 %j) #0 {
  %a1 = getelementptr inbounds <4 x float>* %ptr, i64 %i
  %a2 = load <4 x float>* %a1, align 16, !tbaa !1
  %a3 = trunc i64 %j to i32
  %a4 = extractelement <4 x float> %a2, i32 %a3
  %a5 = insertelement <4 x float> undef, float %a4, i32 0
  %a6 = insertelement <4 x float> %a5, float %a4, i32 1
  %a7 = insertelement <4 x float> %a6, float %a4, i32 2
  %a8 = insertelement <4 x float> %a7, float %a4, i32 3
  ret <4 x float> %a8
}

=================================================

        shlq    $4, %rsi
        addq    %rdi, %rsi
        movslq  %edx, %rax
        vbroadcastss    (%rsi,%rax,4), %xmm0
        retq

=================================================

The movslq is uneeded, but is present because of the trunc to i32 and then
sext back to i64 that the backend adds for vbroadcastss.

We can't remove it because it changes the meaning. The IR that clang
generates is already suboptimal. What clang really should emit is:

  %a4 = extractelement <4 x float> %a2, i64 %j

This patch makes that legal. A separate patch will teach clang to do it.

Differential Revision: http://reviews.llvm.org/D3519

llvm-svn: 207801
This commit is contained in:
Michael J. Spencer 2014-05-01 22:12:39 +00:00
parent 8e6ddf2de1
commit eeeb060307
7 changed files with 57 additions and 19 deletions
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8
docs/LangRef.rst
View File

@ -4470,7 +4470,7 @@ Syntax:
::
<result> = extractelement <n x <ty>> <val>, i32 <idx> ; yields <ty>
<result> = extractelement <n x <ty>> <val>, <ty2> <idx> ; yields <ty>
Overview:
"""""""""
@ -4484,7 +4484,7 @@ Arguments:
The first operand of an '``extractelement``' instruction is a value of
:ref:`vector <t_vector>` type. The second operand is an index indicating
the position from which to extract the element. The index may be a
variable.
variable of any integer type.
Semantics:
""""""""""
@ -4510,7 +4510,7 @@ Syntax:
::
<result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> ; yields <n x <ty>>
<result> = insertelement <n x <ty>> <val>, <ty> <elt>, <ty2> <idx> ; yields <n x <ty>>
Overview:
"""""""""
@ -4525,7 +4525,7 @@ The first operand of an '``insertelement``' instruction is a value of
:ref:`vector <t_vector>` type. The second operand is a scalar value whose
type must equal the element type of the first operand. The third operand
is an index indicating the position at which to insert the value. The
index may be a variable.
index may be a variable of any integer type.
Semantics:
""""""""""

34
lib/Bitcode/Reader/BitcodeReader.cpp
View File

@ -1418,7 +1418,8 @@ error_code BitcodeReader::ParseConstants() {
ValueList.getConstantFwdRef(Record[2],CurTy));
break;
}
case bitc::CST_CODE_CE_EXTRACTELT: { // CE_EXTRACTELT: [opty, opval, opval]
case bitc::CST_CODE_CE_EXTRACTELT
: { // CE_EXTRACTELT: [opty, opval, opty, opval]
if (Record.size() < 3)
return Error(InvalidRecord);
VectorType *OpTy =
@ -1426,20 +1427,37 @@ error_code BitcodeReader::ParseConstants() {
if (!OpTy)
return Error(InvalidRecord);
Constant *Op0 = ValueList.getConstantFwdRef(Record[1], OpTy);
Constant *Op1 = ValueList.getConstantFwdRef(Record[2],
Type::getInt32Ty(Context));
Constant *Op1 = nullptr;
if (Record.size() == 4) {
Type *IdxTy = getTypeByID(Record[2]);
if (!IdxTy)
return Error(InvalidRecord);
Op1 = ValueList.getConstantFwdRef(Record[3], IdxTy);
} else // TODO: Remove with llvm 4.0
Op1 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
if (!Op1)
return Error(InvalidRecord);
V = ConstantExpr::getExtractElement(Op0, Op1);
break;
}
case bitc::CST_CODE_CE_INSERTELT: { // CE_INSERTELT: [opval, opval, opval]
case bitc::CST_CODE_CE_INSERTELT
: { // CE_INSERTELT: [opval, opval, opty, opval]
VectorType *OpTy = dyn_cast<VectorType>(CurTy);
if (Record.size() < 3 || !OpTy)
return Error(InvalidRecord);
Constant *Op0 = ValueList.getConstantFwdRef(Record[0], OpTy);
Constant *Op1 = ValueList.getConstantFwdRef(Record[1],
OpTy->getElementType());
Constant *Op2 = ValueList.getConstantFwdRef(Record[2],
Type::getInt32Ty(Context));
Constant *Op2 = nullptr;
if (Record.size() == 4) {
Type *IdxTy = getTypeByID(Record[2]);
if (!IdxTy)
return Error(InvalidRecord);
Op2 = ValueList.getConstantFwdRef(Record[3], IdxTy);
} else // TODO: Remove with llvm 4.0
Op2 = ValueList.getConstantFwdRef(Record[2], Type::getInt32Ty(Context));
if (!Op2)
return Error(InvalidRecord);
V = ConstantExpr::getInsertElement(Op0, Op1, Op2);
break;
}
@ -2460,7 +2478,7 @@ error_code BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Vec, *Idx;
if (getValueTypePair(Record, OpNum, NextValueNo, Vec) ||
popValue(Record, OpNum, NextValueNo, Type::getInt32Ty(Context), Idx))
getValueTypePair(Record, OpNum, NextValueNo, Idx))
return Error(InvalidRecord);
I = ExtractElementInst::Create(Vec, Idx);
InstructionList.push_back(I);
@ -2473,7 +2491,7 @@ error_code BitcodeReader::ParseFunctionBody(Function *F) {
if (getValueTypePair(Record, OpNum, NextValueNo, Vec) ||
popValue(Record, OpNum, NextValueNo,
cast<VectorType>(Vec->getType())->getElementType(), Elt) ||
popValue(Record, OpNum, NextValueNo, Type::getInt32Ty(Context), Idx))
getValueTypePair(Record, OpNum, NextValueNo, Idx))
return Error(InvalidRecord);
I = InsertElementInst::Create(Vec, Elt, Idx);
InstructionList.push_back(I);

6
lib/Bitcode/Writer/BitcodeWriter.cpp
View File

@ -1087,12 +1087,14 @@ static void WriteConstants(unsigned FirstVal, unsigned LastVal,
Code = bitc::CST_CODE_CE_EXTRACTELT;
Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
Record.push_back(VE.getValueID(C->getOperand(0)));
Record.push_back(VE.getTypeID(C->getOperand(1)->getType()));
Record.push_back(VE.getValueID(C->getOperand(1)));
break;
case Instruction::InsertElement:
Code = bitc::CST_CODE_CE_INSERTELT;
Record.push_back(VE.getValueID(C->getOperand(0)));
Record.push_back(VE.getValueID(C->getOperand(1)));
Record.push_back(VE.getTypeID(C->getOperand(2)->getType()));
Record.push_back(VE.getValueID(C->getOperand(2)));
break;
case Instruction::ShuffleVector:
@ -1253,13 +1255,13 @@ static void WriteInstruction(const Instruction &I, unsigned InstID,
case Instruction::ExtractElement:
Code = bitc::FUNC_CODE_INST_EXTRACTELT;
PushValueAndType(I.getOperand(0), InstID, Vals, VE);
pushValue(I.getOperand(1), InstID, Vals, VE);
PushValueAndType(I.getOperand(1), InstID, Vals, VE);
break;
case Instruction::InsertElement:
Code = bitc::FUNC_CODE_INST_INSERTELT;
PushValueAndType(I.getOperand(0), InstID, Vals, VE);
pushValue(I.getOperand(1), InstID, Vals, VE);
pushValue(I.getOperand(2), InstID, Vals, VE);
PushValueAndType(I.getOperand(2), InstID, Vals, VE);
break;
case Instruction::ShuffleVector:
Code = bitc::FUNC_CODE_INST_SHUFFLEVEC;

6
lib/IR/Constants.cpp
View File

@ -1937,8 +1937,8 @@ ConstantExpr::getFCmp(unsigned short pred, Constant *LHS, Constant *RHS) {
Constant *ConstantExpr::getExtractElement(Constant *Val, Constant *Idx) {
assert(Val->getType()->isVectorTy() &&
"Tried to create extractelement operation on non-vector type!");
assert(Idx->getType()->isIntegerTy(32) &&
"Extractelement index must be i32 type!");
assert(Idx->getType()->isIntegerTy() &&
"Extractelement index must be an integer type!");
if (Constant *FC = ConstantFoldExtractElementInstruction(Val, Idx))
return FC; // Fold a few common cases.
@ -1958,7 +1958,7 @@ Constant *ConstantExpr::getInsertElement(Constant *Val, Constant *Elt,
"Tried to create insertelement operation on non-vector type!");
assert(Elt->getType() == Val->getType()->getVectorElementType() &&
"Insertelement types must match!");
assert(Idx->getType()->isIntegerTy(32) &&
assert(Idx->getType()->isIntegerTy() &&
"Insertelement index must be i32 type!");
if (Constant *FC = ConstantFoldInsertElementInstruction(Val, Elt, Idx))

4
lib/IR/Instructions.cpp
View File

@ -1479,7 +1479,7 @@ ExtractElementInst::ExtractElementInst(Value *Val, Value *Index,
bool ExtractElementInst::isValidOperands(const Value *Val, const Value *Index) {
if (!Val->getType()->isVectorTy() || !Index->getType()->isIntegerTy(32))
if (!Val->getType()->isVectorTy() || !Index->getType()->isIntegerTy())
return false;
return true;
}
@ -1526,7 +1526,7 @@ bool InsertElementInst::isValidOperands(const Value *Vec, const Value *Elt,
if (Elt->getType() != cast<VectorType>(Vec->getType())->getElementType())
return false;// Second operand of insertelement must be vector element type.
if (!Index->getType()->isIntegerTy(32))
if (!Index->getType()->isIntegerTy())
return false; // Third operand of insertelement must be i32.
return true;
}

16
test/CodeGen/X86/vec_splat.ll
View File

@ -32,3 +32,19 @@ define void @test_v2sd(<2 x double>* %P, <2 x double>* %Q, double %X) nounwind {
; SSE3-LABEL: test_v2sd:
; SSE3: movddup
}
; Fold extract of a load into the load's address computation. This avoids spilling to the stack.
define <4 x float> @load_extract_splat(<4 x float>* nocapture readonly %ptr, i64 %i, i64 %j) nounwind {
%1 = getelementptr inbounds <4 x float>* %ptr, i64 %i
%2 = load <4 x float>* %1, align 16
%3 = extractelement <4 x float> %2, i64 %j
%4 = insertelement <4 x float> undef, float %3, i32 0
%5 = insertelement <4 x float> %4, float %3, i32 1
%6 = insertelement <4 x float> %5, float %3, i32 2
%7 = insertelement <4 x float> %6, float %3, i32 3
ret <4 x float> %7
; AVX-LABEL: load_extract_splat
; AVX-NOT: movs
; AVX: vbroadcastss
}

2
test/Feature/instructions.ll
View File

@ -4,11 +4,13 @@
define i32 @test_extractelement(<4 x i32> %V) {
%R = extractelement <4 x i32> %V, i32 1 ; <i32> [#uses=1]
%S = extractelement <4 x i32> %V, i64 1 ; <i32> [#uses=0]
ret i32 %R
}
define <4 x i32> @test_insertelement(<4 x i32> %V) {
%R = insertelement <4 x i32> %V, i32 0, i32 0 ; <<4 x i32>> [#uses=1]
%S = insertelement <4 x i32> %V, i32 0, i64 0 ; <<4 x i32>> [#uses=0]
ret <4 x i32> %R
}