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Implement (A&((~A)|B)) -> A&B transformation in the instruction combiner. This

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takes care of all permutations of this pattern.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60290 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2008-11-30 13:08:13 +00:00
parent 7c7048ecc6
commit 7f0ef6b325
3 changed files with 55 additions and 10 deletions
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10
lib/Target/README.txt
View File

@ -1086,16 +1086,6 @@ produces better code on X86.
//===---------------------------------------------------------------------===//
From GCC Bug 33512:
int f(int y, int x)
{
return x & ((~x) | y);
}
Should combine to x & y. Currently not optimized with "clang
-emit-llvm-bc | opt -std-compile-opts".
//===---------------------------------------------------------------------===//
From GCC Bug 15784:
#define abs(x) x>0?x:-x
int f(int x, int y)

19
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -3993,6 +3993,7 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
std::swap(Op0, Op1);
}
}
if (Op1->hasOneUse() &&
match(Op1, m_Xor(m_Value(A), m_Value(B)))) {
if (B == Op0) { // B&(A^B) -> B&(B^A)
@ -4005,6 +4006,24 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
return BinaryOperator::CreateAnd(A, NotB);
}
}
// (A&((~A)|B)) -> A&B
if (match(Op0, m_Or(m_Not(m_Value(A)), m_Value(B)))) {
if (A == Op1)
return BinaryOperator::CreateAnd(A, B);
}
if (match(Op0, m_Or(m_Value(A), m_Not(m_Value(B))))) {
if (B == Op1)
return BinaryOperator::CreateAnd(A, B);
}
if (match(Op1, m_Or(m_Not(m_Value(A)), m_Value(B)))) {
if (A == Op0)
return BinaryOperator::CreateAnd(A, B);
}
if (match(Op1, m_Or(m_Value(A), m_Not(m_Value(B))))) {
if (B == Op0)
return BinaryOperator::CreateAnd(A, B);
}
}
if (ICmpInst *RHS = dyn_cast<ICmpInst>(Op1)) {

36
test/Transforms/InstCombine/and-not-or.ll Normal file
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@ -0,0 +1,36 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {and i32 %y, %x} | count 2
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {and i32 %x, %y} | count 2
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {xor}
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {or}
define i32 @func1(i32 %x, i32 %y) nounwind {
entry:
%n = xor i32 %y, -1
%o = or i32 %n, %x
%a = and i32 %o, %y
ret i32 %a
}
define i32 @func2(i32 %x, i32 %y) nounwind {
entry:
%n = xor i32 %y, -1
%o = or i32 %x, %n
%a = and i32 %o, %y
ret i32 %a
}
define i32 @func3(i32 %x, i32 %y) nounwind {
entry:
%n = xor i32 %y, -1
%o = or i32 %n, %x
%a = and i32 %y, %o
ret i32 %a
}
define i32 @func4(i32 %x, i32 %y) nounwind {
entry:
%n = xor i32 %y, -1
%o = or i32 %x, %n
%a = and i32 %y, %o
ret i32 %a
}