[InstCombine] Generalize sub of selects optimization to all BinaryOperators

This exposes further optimization opportunities if the selects are
correlated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242235 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
2015-07-14 22:39:23 +00:00
parent d640af829c
commit 137ad1ded9
3 changed files with 37 additions and 26 deletions

View File

@@ -623,6 +623,33 @@ Value *InstCombiner::SimplifyUsingDistributiveLaws(BinaryOperator &I) {
}
}
// (op (select (a, c, b)), (select (a, d, b))) -> (select (a, (op c, d), 0))
// (op (select (a, b, c)), (select (a, b, d))) -> (select (a, 0, (op c, d)))
if (auto *SI0 = dyn_cast<SelectInst>(LHS)) {
if (auto *SI1 = dyn_cast<SelectInst>(RHS)) {
if (SI0->getCondition() == SI1->getCondition()) {
Value *SI = nullptr;
if (Value *V = SimplifyBinOp(TopLevelOpcode, SI0->getFalseValue(),
SI1->getFalseValue(), DL, TLI, DT, AC))
SI = Builder->CreateSelect(SI0->getCondition(),
Builder->CreateBinOp(TopLevelOpcode,
SI0->getTrueValue(),
SI1->getTrueValue()),
V);
if (Value *V = SimplifyBinOp(TopLevelOpcode, SI0->getTrueValue(),
SI1->getTrueValue(), DL, TLI, DT, AC))
SI = Builder->CreateSelect(
SI0->getCondition(), V,
Builder->CreateBinOp(TopLevelOpcode, SI0->getFalseValue(),
SI1->getFalseValue()));
if (SI) {
SI->takeName(&I);
return SI;
}
}
}
}
return nullptr;
}