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InstSimplify: Simplify trivial and/or of icmps

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Some ICmpInsts when anded/ored with another ICmpInst trivially reduces
to true or false depending on whether or not all integers or no integers
satisfy the intersected/unioned range.

This sort of trivial looking code can come about when InstCombine
performs a range reduction-type operation on sdiv and the like.

This fixes PR20916.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217750 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2014-09-15 08:15:28 +00:00
parent 740506d9ca
commit c3e70ca886
2 changed files with 234 additions and 0 deletions
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114
lib/Analysis/InstructionSimplify.cpp
View File

@ -1414,6 +1414,54 @@ Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
RecursionLimit);
}
// Simplify (and (icmp ...) (icmp ...)) to true when we can tell that the range
// of possible values cannot be satisfied.
static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
ConstantInt *CI1, *CI2;
Value *V;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
m_ConstantInt(CI2))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
return nullptr;
Type *ITy = Op0->getType();
auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
bool isNSW = AddInst->hasNoSignedWrap();
bool isNUW = AddInst->hasNoUnsignedWrap();
const APInt &CI1V = CI1->getValue();
const APInt &CI2V = CI2->getValue();
const APInt Delta = CI2V - CI1V;
if (CI1V.isStrictlyPositive()) {
if (Delta == 2) {
if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
return getFalse(ITy);
if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
return getFalse(ITy);
}
if (Delta == 1) {
if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
return getFalse(ITy);
if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
return getFalse(ITy);
}
}
if (CI1V.getBoolValue() && isNUW) {
if (Delta == 2)
if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Delta == 1)
if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
return getFalse(ITy);
}
return nullptr;
}
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
@ -1470,6 +1518,15 @@ static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
return Op1;
}
if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
return V;
if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
return V;
}
}
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
MaxRecurse))
@ -1510,6 +1567,54 @@ Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout *DL,
RecursionLimit);
}
// Simplify (or (icmp ...) (icmp ...)) to true when we can tell that the union
// contains all possible values.
static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
ConstantInt *CI1, *CI2;
Value *V;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
m_ConstantInt(CI2))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
return nullptr;
Type *ITy = Op0->getType();
auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
bool isNSW = AddInst->hasNoSignedWrap();
bool isNUW = AddInst->hasNoUnsignedWrap();
const APInt &CI1V = CI1->getValue();
const APInt &CI2V = CI2->getValue();
const APInt Delta = CI2V - CI1V;
if (CI1V.isStrictlyPositive()) {
if (Delta == 2) {
if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
return getTrue(ITy);
if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
return getTrue(ITy);
}
if (Delta == 1) {
if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
return getTrue(ITy);
if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
return getTrue(ITy);
}
}
if (CI1V.getBoolValue() && isNUW) {
if (Delta == 2)
if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
return getTrue(ITy);
if (Delta == 1)
if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
return nullptr;
}
/// SimplifyOrInst - Given operands for an Or, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
@ -1567,6 +1672,15 @@ static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
(A == Op0 || B == Op0))
return Constant::getAllOnesValue(Op0->getType());
if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
return V;
if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
return V;
}
}
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
MaxRecurse))

120
test/Transforms/InstSimplify/AndOrXor.ll
View File

@ -28,3 +28,123 @@ define i32 @sub_neg_nuw(i32 %x, i32 %y) {
ret i32 %sub
; CHECK: ret i32 %x
}
define i1 @and_of_icmps0(i32 %b) {
; CHECK-LABEL: @and_of_icmps0(
%1 = add i32 %b, 2
%2 = icmp ult i32 %1, 4
%cmp3 = icmp sgt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @and_of_icmps1(i32 %b) {
; CHECK-LABEL: @and_of_icmps1(
%1 = add nsw i32 %b, 2
%2 = icmp slt i32 %1, 4
%cmp3 = icmp sgt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @and_of_icmps2(i32 %b) {
; CHECK-LABEL: @and_of_icmps2(
%1 = add i32 %b, 2
%2 = icmp ule i32 %1, 3
%cmp3 = icmp sgt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @and_of_icmps3(i32 %b) {
; CHECK-LABEL: @and_of_icmps3(
%1 = add nsw i32 %b, 2
%2 = icmp sle i32 %1, 3
%cmp3 = icmp sgt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @and_of_icmps4(i32 %b) {
; CHECK-LABEL: @and_of_icmps4(
%1 = add nuw i32 %b, 2
%2 = icmp ult i32 %1, 4
%cmp3 = icmp ugt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @and_of_icmps5(i32 %b) {
; CHECK-LABEL: @and_of_icmps5(
%1 = add nuw i32 %b, 2
%2 = icmp ule i32 %1, 3
%cmp3 = icmp ugt i32 %b, 2
%cmp = and i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 false
}
define i1 @or_of_icmps0(i32 %b) {
; CHECK-LABEL: @or_of_icmps0(
%1 = add i32 %b, 2
%2 = icmp uge i32 %1, 4
%cmp3 = icmp sle i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}
define i1 @or_of_icmps1(i32 %b) {
; CHECK-LABEL: @or_of_icmps1(
%1 = add nsw i32 %b, 2
%2 = icmp sge i32 %1, 4
%cmp3 = icmp sle i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}
define i1 @or_of_icmps2(i32 %b) {
; CHECK-LABEL: @or_of_icmps2(
%1 = add i32 %b, 2
%2 = icmp ugt i32 %1, 3
%cmp3 = icmp sle i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}
define i1 @or_of_icmps3(i32 %b) {
; CHECK-LABEL: @or_of_icmps3(
%1 = add nsw i32 %b, 2
%2 = icmp sgt i32 %1, 3
%cmp3 = icmp sle i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}
define i1 @or_of_icmps4(i32 %b) {
; CHECK-LABEL: @or_of_icmps4(
%1 = add nuw i32 %b, 2
%2 = icmp uge i32 %1, 4
%cmp3 = icmp ule i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}
define i1 @or_of_icmps5(i32 %b) {
; CHECK-LABEL: @or_of_icmps5(
%1 = add nuw i32 %b, 2
%2 = icmp ugt i32 %1, 3
%cmp3 = icmp ule i32 %b, 2
%cmp = or i1 %2, %cmp3
ret i1 %cmp
; CHECK: ret i1 true
}