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[CodeGenPrepare] Teach the addressing mode matcher how to promote zext.

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I.e., teach it about 'sext (zext a to ty) to ty2' => zext a to ty2.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217629 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2014-09-11 21:22:14 +00:00
parent 85d436d90a
commit dcc0e7eaa1
2 changed files with 71 additions and 13 deletions
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69
lib/CodeGen/CodeGenPrepare.cpp
View File

@ -1297,6 +1297,29 @@ class TypePromotionTransaction {
}
};
/// \brief Build a zero extension instruction.
class ZExtBuilder : public TypePromotionAction {
public:
/// \brief Build a zero extension instruction of \p Opnd producing a \p Ty
/// result.
/// zext Opnd to Ty.
ZExtBuilder(Instruction *InsertPt, Value *Opnd, Type *Ty)
: TypePromotionAction(Inst) {
IRBuilder<> Builder(InsertPt);
Inst = cast<Instruction>(Builder.CreateZExt(Opnd, Ty, "promoted"));
DEBUG(dbgs() << "Do: ZExtBuilder: " << *Inst << "\n");
}
/// \brief Get the built instruction.
Instruction *getBuiltInstruction() { return Inst; }
/// \brief Remove the built instruction.
void undo() override {
DEBUG(dbgs() << "Undo: ZExtBuilder: " << *Inst << "\n");
Inst->eraseFromParent();
}
};
/// \brief Mutate an instruction to another type.
class TypeMutator : public TypePromotionAction {
/// Record the original type.
@ -1425,6 +1448,8 @@ public:
Instruction *createTrunc(Instruction *Opnd, Type *Ty);
/// Same as IRBuilder::createSExt.
Instruction *createSExt(Instruction *Inst, Value *Opnd, Type *Ty);
/// Same as IRBuilder::createZExt.
Instruction *createZExt(Instruction *Inst, Value *Opnd, Type *Ty);
/// Same as Instruction::moveBefore.
void moveBefore(Instruction *Inst, Instruction *Before);
/// @}
@ -1472,6 +1497,14 @@ Instruction *TypePromotionTransaction::createSExt(Instruction *Inst,
return I;
}
Instruction *TypePromotionTransaction::createZExt(Instruction *Inst,
Value *Opnd, Type *Ty) {
std::unique_ptr<ZExtBuilder> Ptr(new ZExtBuilder(Inst, Opnd, Ty));
Instruction *I = Ptr->getBuiltInstruction();
Actions.push_back(std::move(Ptr));
return I;
}
void TypePromotionTransaction::moveBefore(Instruction *Inst,
Instruction *Before) {
Actions.push_back(
@ -1684,16 +1717,16 @@ class TypePromotionHelper {
}
/// \brief Utility function to promote the operand of \p SExt when this
/// operand is a promotable trunc or sext.
/// operand is a promotable trunc or sext or zext.
/// \p PromotedInsts maps the instructions to their type before promotion.
/// \p CreatedInsts[out] contains how many non-free instructions have been
/// created to promote the operand of SExt.
/// Should never be called directly.
/// \return The promoted value which is used instead of SExt.
static Value *promoteOperandForTruncAndSExt(Instruction *SExt,
TypePromotionTransaction &TPT,
InstrToOrigTy &PromotedInsts,
unsigned &CreatedInsts);
static Value *promoteOperandForTruncAndAnyExt(Instruction *SExt,
TypePromotionTransaction &TPT,
InstrToOrigTy &PromotedInsts,
unsigned &CreatedInsts);
/// \brief Utility function to promote the operand of \p SExt when this
/// operand is promotable and is not a supported trunc or sext.
@ -1729,8 +1762,8 @@ public:
bool TypePromotionHelper::canGetThrough(const Instruction *Inst,
Type *ConsideredSExtType,
const InstrToOrigTy &PromotedInsts) {
// We can always get through sext.
if (isa<SExtInst>(Inst))
// We can always get through sext or zext.
if (isa<SExtInst>(Inst) || isa<ZExtInst>(Inst))
return true;
// We can get through binary operator, if it is legal. In other words, the
@ -1798,8 +1831,9 @@ TypePromotionHelper::Action TypePromotionHelper::getAction(
// SExt or Trunc instructions.
// Return the related handler.
if (isa<SExtInst>(SExtOpnd) || isa<TruncInst>(SExtOpnd))
return promoteOperandForTruncAndSExt;
if (isa<SExtInst>(SExtOpnd) || isa<TruncInst>(SExtOpnd) ||
isa<ZExtInst>(SExtOpnd))
return promoteOperandForTruncAndAnyExt;
// Regular instruction.
// Abort early if we will have to insert non-free instructions.
@ -1809,15 +1843,24 @@ TypePromotionHelper::Action TypePromotionHelper::getAction(
return promoteOperandForOther;
}
Value *TypePromotionHelper::promoteOperandForTruncAndSExt(
Value *TypePromotionHelper::promoteOperandForTruncAndAnyExt(
llvm::Instruction *SExt, TypePromotionTransaction &TPT,
InstrToOrigTy &PromotedInsts, unsigned &CreatedInsts) {
// By construction, the operand of SExt is an instruction. Otherwise we cannot
// get through it and this method should not be called.
Instruction *SExtOpnd = cast<Instruction>(SExt->getOperand(0));
// Replace sext(trunc(opnd)) or sext(sext(opnd))
// => sext(opnd).
TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
if (isa<ZExtInst>(SExtOpnd)) {
// Replace sext(zext(opnd))
// => zext(opnd).
Instruction *ZExt =
TPT.createZExt(SExt, SExtOpnd->getOperand(0), SExt->getType());
TPT.replaceAllUsesWith(SExt, ZExt);
TPT.eraseInstruction(SExt);
} else {
// Replace sext(trunc(opnd)) or sext(sext(opnd))
// => sext(opnd).
TPT.setOperand(SExt, 0, SExtOpnd->getOperand(0));
}
CreatedInsts = 0;
// Remove dead code.

15
test/CodeGen/X86/codegen-prepare-addrmode-sext.ll
View File

@ -67,6 +67,21 @@ define i8 @oneArgPromotion(i32 %arg1, i8* %base) {
ret i8 %res
}
; Check that we are able to merge a sign extension with a zero extension.
; CHECK-LABEL: @oneArgPromotionZExt
; CHECK: [[ARG1ZEXT:%[a-zA-Z_0-9-]+]] = zext i8 %arg1 to i64
; CHECK: [[PROMOTED:%[a-zA-Z_0-9-]+]] = add nsw i64 [[ARG1ZEXT]], 1
; CHECK: getelementptr inbounds i8* %base, i64 [[PROMOTED]]
; CHECK: ret
define i8 @oneArgPromotionZExt(i8 %arg1, i8* %base) {
%zext = zext i8 %arg1 to i32
%add = add nsw i32 %zext, 1
%sextadd = sext i32 %add to i64
%arrayidx = getelementptr inbounds i8* %base, i64 %sextadd
%res = load i8* %arrayidx
ret i8 %res
}
; Check that we do not promote truncate when we cannot determine the
; bits that are dropped.
; CHECK-LABEL: @oneArgPromotionBlockTrunc1