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Implement add.ll:test29. Codegening:

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struct S { unsigned int i : 6, j : 11, k : 15; } b;
void plus1 (unsigned int x) {
  b.i += x;
}

as:
_plus1:
        lis r2, ha16(L_b$non_lazy_ptr)
        lwz r2, lo16(L_b$non_lazy_ptr)(r2)
        lwz r4, 0(r2)
        add r3, r4, r3
        rlwimi r3, r4, 0, 0, 25
        stw r3, 0(r2)
        blr

instead of:

_plus1:
        lis r2, ha16(L_b$non_lazy_ptr)
        lwz r2, lo16(L_b$non_lazy_ptr)(r2)
        lwz r4, 0(r2)
        rlwinm r5, r4, 0, 26, 31
        add r3, r5, r3
        rlwimi r3, r4, 0, 0, 25
        stw r3, 0(r2)
        blr

llvm-svn: 23379
This commit is contained in:
Chris Lattner 2005-09-18 04:24:45 +00:00
parent dd10722054
commit fa22870351
1 changed files with 66 additions and 0 deletions
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66
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -222,6 +222,9 @@ namespace {
Instruction *OptAndOp(Instruction *Op, ConstantIntegral *OpRHS,
ConstantIntegral *AndRHS, BinaryOperator &TheAnd);
Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantIntegral *Mask,
bool isSub, Instruction &I);
Instruction *InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
bool Inside, Instruction &IB);
@ -1570,6 +1573,46 @@ Instruction *InstCombiner::InsertRangeTest(Value *V, Constant *Lo, Constant *Hi,
return new SetCondInst(Instruction::SetGT, OffsetVal, AddCST);
}
/// FoldLogicalPlusAnd - We know that Mask is of the form 0+1+, and that this is
/// part of an expression (LHS +/- RHS) & Mask, where isSub determines whether
/// the operator is a sub. If we can fold one of the following xforms:
///
/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
///
/// return (A +/- B).
///
Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
ConstantIntegral *Mask, bool isSub,
Instruction &I) {
Instruction *LHSI = dyn_cast<Instruction>(LHS);
if (!LHSI || LHSI->getNumOperands() != 2 ||
!isa<ConstantInt>(LHSI->getOperand(1))) return 0;
ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
switch (LHSI->getOpcode()) {
default: return 0;
case Instruction::And:
if (ConstantExpr::getAnd(N, Mask) == Mask)
break;
return 0;
case Instruction::Or:
case Instruction::Xor:
if (ConstantExpr::getAnd(N, Mask)->isNullValue())
break;
return 0;
}
Instruction *New;
if (isSub)
New = BinaryOperator::createSub(LHSI->getOperand(0), RHS, "fold");
else
New = BinaryOperator::createAdd(LHSI->getOperand(0), RHS, "fold");
return InsertNewInstBefore(New, I);
}
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
@ -1640,6 +1683,29 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
MaskedValueIsZero(Op0RHS, AndRHS))
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
break;
case Instruction::Add:
// If the AndRHS is a power of two minus one (0+1+).
if ((AndRHS->getRawValue() & AndRHS->getRawValue()+1) == 0) {
// ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
// ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
// ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
return BinaryOperator::createAnd(V, AndRHS);
if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
return BinaryOperator::createAnd(V, AndRHS); // Add commutes
}
break;
case Instruction::Sub:
// If the AndRHS is a power of two minus one (0+1+).
if ((AndRHS->getRawValue() & AndRHS->getRawValue()+1) == 0) {
// ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
// ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
// ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
return BinaryOperator::createAnd(V, AndRHS);
}
break;
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))