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Implement ((A|B)&1)|(B&-2) -> (A&1) | B transformation. This also takes care of

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permutations of this pattern.

llvm-svn: 60312
This commit is contained in:
Bill Wendling 2008-12-01 01:07:11 +00:00
parent 401743c904
commit 23684a026c
3 changed files with 106 additions and 6 deletions
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6
lib/Target/README.txt
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@ -1147,12 +1147,6 @@ There's an unnecessary zext in the generated code with "clang
//===---------------------------------------------------------------------===//
int a(int a, int b) {return ((a|b)&1) | (b&-2);}
Should be combined to "(a&1)|b". Currently not optimized with "clang
-emit-llvm-bc | opt -std-compile-opts".
//===---------------------------------------------------------------------===//
int a(unsigned b) {return ((b << 31) | (b << 30)) >> 31;}
Should be combined to "((b >> 1) | b) & 1". Currently not optimized
with "clang -emit-llvm-bc | opt -std-compile-opts".

67
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4649,6 +4649,73 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
}
}
// ((A|B)&1)|(B&-2) -> (A&1) | B
if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
if (CI->getValue() == 1) {
Value *V1 = 0, *C2 = 0;
if (match(Op1, m_And(m_Value(V1), m_Value(C2)))) {
ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
if (!CI2) {
std::swap(V1, C2);
CI2 = dyn_cast<ConstantInt>(C2);
}
if (CI2) {
APInt NegTwo = -APInt(CI2->getValue().getBitWidth(), 2, true);
if (CI2->getValue().eq(NegTwo)) {
if (V1 == B) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI), I);
return BinaryOperator::CreateOr(NewOp, B);
}
if (V1 == A) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI), I);
return BinaryOperator::CreateOr(NewOp, A);
}
}
}
}
}
}
}
// (B&-2)|((A|B)&1) -> (A&1) | B
if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
if (CI->getValue() == 1) {
Value *V1 = 0, *C2 = 0;
if (match(Op0, m_And(m_Value(V1), m_Value(C2)))) {
ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
if (!CI2) {
std::swap(V1, C2);
CI2 = dyn_cast<ConstantInt>(C2);
}
if (CI2) {
APInt NegTwo = -APInt(CI2->getValue().getBitWidth(), 2, true);
if (CI2->getValue().eq(NegTwo)) {
if (V1 == B) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI), I);
return BinaryOperator::CreateOr(NewOp, B);
}
if (V1 == A) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI), I);
return BinaryOperator::CreateOr(NewOp, A);
}
}
}
}
}
}
}
if (match(Op0, m_Not(m_Value(A)))) { // ~A | Op1
if (A == Op1) // ~A | A == -1
return ReplaceInstUsesWith(I, Constant::getAllOnesValue(I.getType()));

39
test/Transforms/InstCombine/and-or.ll Normal file
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@ -0,0 +1,39 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {and i32 %a, 1} | count 4
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {or i32 %0, %b} | count 4
define i32 @func1(i32 %a, i32 %b) nounwind readnone {
entry:
%0 = or i32 %b, %a ; <i32> [#uses=1]
%1 = and i32 %0, 1 ; <i32> [#uses=1]
%2 = and i32 %b, -2 ; <i32> [#uses=1]
%3 = or i32 %1, %2 ; <i32> [#uses=1]
ret i32 %3
}
define i32 @func2(i32 %a, i32 %b) nounwind readnone {
entry:
%0 = or i32 %a, %b ; <i32> [#uses=1]
%1 = and i32 1, %0 ; <i32> [#uses=1]
%2 = and i32 -2, %b ; <i32> [#uses=1]
%3 = or i32 %1, %2 ; <i32> [#uses=1]
ret i32 %3
}
define i32 @func3(i32 %a, i32 %b) nounwind readnone {
entry:
%0 = or i32 %b, %a ; <i32> [#uses=1]
%1 = and i32 %0, 1 ; <i32> [#uses=1]
%2 = and i32 %b, -2 ; <i32> [#uses=1]
%3 = or i32 %2, %1 ; <i32> [#uses=1]
ret i32 %3
}
define i32 @func4(i32 %a, i32 %b) nounwind readnone {
entry:
%0 = or i32 %a, %b ; <i32> [#uses=1]
%1 = and i32 1, %0 ; <i32> [#uses=1]
%2 = and i32 -2, %b ; <i32> [#uses=1]
%3 = or i32 %2, %1 ; <i32> [#uses=1]
ret i32 %3
}