Canonicalize sext(i1) to i1?-1:0, and update various instcombine
optimizations accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58457 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 4ec36ad..70b5aef 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2012,6 +2012,14 @@
KnownZero, KnownOne))
return &I;
}
+
+ // zext(i1) - 1 -> select i1, 0, -1
+ if (ZExtInst *ZI = dyn_cast<ZExtInst>(LHS))
+ if (CI->isAllOnesValue() &&
+ ZI->getOperand(0)->getType() == Type::Int1Ty)
+ return SelectInst::Create(ZI->getOperand(0),
+ Constant::getNullValue(I.getType()),
+ ConstantInt::getAllOnesValue(I.getType()));
}
if (isa<PHINode>(LHS))
@@ -4338,24 +4346,55 @@
}
}
- // (A & sext(C0)) | (B & ~sext(C0) -> C0 ? A : B
- if (isa<SExtInst>(C) &&
- cast<User>(C)->getOperand(0)->getType() == Type::Int1Ty) {
+ // (A & (C0?-1:0)) | (B & ~(C0?-1:0)) -> C0 ? A : B, and commuted variants
+ if (match(A, m_Select(m_Value(), m_ConstantInt(-1), m_ConstantInt(0)))) {
+ if (match(D, m_Not(m_Value(A))))
+ return SelectInst::Create(cast<User>(A)->getOperand(0), C, B);
+ if (match(B, m_Not(m_Value(A))))
+ return SelectInst::Create(cast<User>(A)->getOperand(0), C, D);
+ }
+ if (match(B, m_Select(m_Value(), m_ConstantInt(-1), m_ConstantInt(0)))) {
+ if (match(C, m_Not(m_Value(B))))
+ return SelectInst::Create(cast<User>(B)->getOperand(0), A, D);
+ if (match(A, m_Not(m_Value(B))))
+ return SelectInst::Create(cast<User>(B)->getOperand(0), C, D);
+ }
+ if (match(C, m_Select(m_Value(), m_ConstantInt(-1), m_ConstantInt(0)))) {
if (match(D, m_Not(m_Value(C))))
return SelectInst::Create(cast<User>(C)->getOperand(0), A, B);
- // And commutes, try both ways.
if (match(B, m_Not(m_Value(C))))
return SelectInst::Create(cast<User>(C)->getOperand(0), A, D);
}
- // Or commutes, try both ways.
- if (isa<SExtInst>(D) &&
- cast<User>(D)->getOperand(0)->getType() == Type::Int1Ty) {
+ if (match(D, m_Select(m_Value(), m_ConstantInt(-1), m_ConstantInt(0)))) {
if (match(C, m_Not(m_Value(D))))
return SelectInst::Create(cast<User>(D)->getOperand(0), A, B);
- // And commutes, try both ways.
if (match(A, m_Not(m_Value(D))))
return SelectInst::Create(cast<User>(D)->getOperand(0), C, B);
}
+ if (match(A, m_Select(m_Value(), m_ConstantInt(0), m_ConstantInt(-1)))) {
+ if (match(D, m_Not(m_Value(A))))
+ return SelectInst::Create(cast<User>(A)->getOperand(0), B, C);
+ if (match(B, m_Not(m_Value(A))))
+ return SelectInst::Create(cast<User>(A)->getOperand(0), D, C);
+ }
+ if (match(B, m_Select(m_Value(), m_ConstantInt(0), m_ConstantInt(-1)))) {
+ if (match(C, m_Not(m_Value(B))))
+ return SelectInst::Create(cast<User>(B)->getOperand(0), D, A);
+ if (match(A, m_Not(m_Value(B))))
+ return SelectInst::Create(cast<User>(B)->getOperand(0), D, C);
+ }
+ if (match(C, m_Select(m_Value(), m_ConstantInt(0), m_ConstantInt(-1)))) {
+ if (match(D, m_Not(m_Value(C))))
+ return SelectInst::Create(cast<User>(C)->getOperand(0), B, A);
+ if (match(B, m_Not(m_Value(C))))
+ return SelectInst::Create(cast<User>(C)->getOperand(0), D, A);
+ }
+ if (match(D, m_Select(m_Value(), m_ConstantInt(0), m_ConstantInt(-1)))) {
+ if (match(C, m_Not(m_Value(D))))
+ return SelectInst::Create(cast<User>(D)->getOperand(0), B, A);
+ if (match(A, m_Not(m_Value(D))))
+ return SelectInst::Create(cast<User>(D)->getOperand(0), B, C);
+ }
}
// (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
@@ -7965,37 +8004,11 @@
Value *Src = CI.getOperand(0);
- // sext (x <s 0) -> ashr x, 31 -> all ones if signed
- // sext (x >s -1) -> ashr x, 31 -> all ones if not signed
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(Src)) {
- // If we are just checking for a icmp eq of a single bit and zext'ing it
- // to an integer, then shift the bit to the appropriate place and then
- // cast to integer to avoid the comparison.
- if (ConstantInt *Op1C = dyn_cast<ConstantInt>(ICI->getOperand(1))) {
- const APInt &Op1CV = Op1C->getValue();
-
- // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
- // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
- if ((ICI->getPredicate() == ICmpInst::ICMP_SLT && Op1CV == 0) ||
- (ICI->getPredicate() == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())){
- Value *In = ICI->getOperand(0);
- Value *Sh = ConstantInt::get(In->getType(),
- In->getType()->getPrimitiveSizeInBits()-1);
- In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
- In->getName()+".lobit"),
- CI);
- if (In->getType() != CI.getType())
- In = CastInst::CreateIntegerCast(In, CI.getType(),
- true/*SExt*/, "tmp", &CI);
-
- if (ICI->getPredicate() == ICmpInst::ICMP_SGT)
- In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
- In->getName()+".not"), CI);
-
- return ReplaceInstUsesWith(CI, In);
- }
- }
- }
+ // Canonicalize sign-extend from i1 to a select.
+ if (Src->getType() == Type::Int1Ty)
+ return SelectInst::Create(Src,
+ ConstantInt::getAllOnesValue(CI.getType()),
+ Constant::getNullValue(CI.getType()));
// See if the value being truncated is already sign extended. If so, just
// eliminate the trunc/sext pair.
@@ -8468,7 +8481,7 @@
// can be adjusted to fit the min/max idiom. We may edit ICI in
// place here, so make sure the select is the only user.
if (ICI->hasOneUse())
- if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS))
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_ULT:
@@ -8513,6 +8526,44 @@
}
}
+ // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
+ // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
+ CmpInst::Predicate Pred = ICI->getPredicate();
+ if (match(TrueVal, m_ConstantInt(0)) &&
+ match(FalseVal, m_ConstantInt(-1)))
+ Pred = CmpInst::getInversePredicate(Pred);
+ else if (!match(TrueVal, m_ConstantInt(-1)) ||
+ !match(FalseVal, m_ConstantInt(0)))
+ Pred = CmpInst::BAD_ICMP_PREDICATE;
+ if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
+ // If we are just checking for a icmp eq of a single bit and zext'ing it
+ // to an integer, then shift the bit to the appropriate place and then
+ // cast to integer to avoid the comparison.
+ const APInt &Op1CV = CI->getValue();
+
+ // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
+ // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
+ if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
+ (Pred == ICmpInst::ICMP_SGT &&Op1CV.isAllOnesValue())) {
+ Value *In = ICI->getOperand(0);
+ Value *Sh = ConstantInt::get(In->getType(),
+ In->getType()->getPrimitiveSizeInBits()-1);
+ In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
+ In->getName()+".lobit"),
+ *ICI);
+ if (In->getType() != CI->getType())
+ In = CastInst::CreateIntegerCast(In, CI->getType(),
+ true/*SExt*/, "tmp", ICI);
+
+ if (Pred == ICmpInst::ICMP_SGT)
+ In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
+ In->getName()+".not"), *ICI);
+
+ return ReplaceInstUsesWith(SI, In);
+ }
+ }
+ }
+
if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
// Transform (X == Y) ? X : Y -> Y
if (Pred == ICmpInst::ICMP_EQ)