diff options
| author | Benjamin Kramer <benny.kra@googlemail.com> | 2010-12-22 23:12:15 +0000 |
|---|---|---|
| committer | Benjamin Kramer <benny.kra@googlemail.com> | 2010-12-22 23:12:15 +0000 |
| commit | 8ef5001b277a72a3c84e60acc698f7f28bf3caa0 (patch) | |
| tree | 7c2009a947d31ded93b8feeb17ebe9f1bd9e6ab3 | |
| parent | 7f8e7681adce83f3abe0a2f2cfccb41788b73bd9 (diff) | |
| download | bcm5719-llvm-8ef5001b277a72a3c84e60acc698f7f28bf3caa0.tar.gz bcm5719-llvm-8ef5001b277a72a3c84e60acc698f7f28bf3caa0.zip | |
InstCombine: creating selects from -1 and 0 is fine, they combine into a sext from i1.
llvm-svn: 122453
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/select.ll | 12 |
2 files changed, 18 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp index 82ce31128c8..c15378bc742 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -195,7 +195,10 @@ static bool isSelect01(Constant *C1, Constant *C2) { ConstantInt *C2I = dyn_cast<ConstantInt>(C2); if (!C2I) return false; - return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne()); + if (!C1I->isZero() && !C2I->isZero()) // One side must be zero. + return false; + return C1I->isOne() || C1I->isAllOnesValue() || + C2I->isOne() || C2I->isAllOnesValue(); } /// FoldSelectIntoOp - Try fold the select into one of the operands to @@ -219,7 +222,7 @@ Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal, Constant *C = GetSelectFoldableConstant(TVI); Value *OOp = TVI->getOperand(2-OpToFold); // Avoid creating select between 2 constants unless it's selecting - // between 0 and 1. + // between 0, 1 and -1. if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C); InsertNewInstBefore(NewSel, SI); @@ -248,7 +251,7 @@ Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal, Constant *C = GetSelectFoldableConstant(FVI); Value *OOp = FVI->getOperand(2-OpToFold); // Avoid creating select between 2 constants unless it's selecting - // between 0 and 1. + // between 0, 1 and -1. if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) { Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp); InsertNewInstBefore(NewSel, SI); diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll index 772299c29f9..fd3937d3da2 100644 --- a/llvm/test/Transforms/InstCombine/select.ll +++ b/llvm/test/Transforms/InstCombine/select.ll @@ -584,3 +584,15 @@ define i32 @test41(i1 %cond, i32 %x, i32 %y) { ; CHECK-NEXT: and i32 %x, %y ; CHECK-NEXT: ret i32 } + +define i32 @test42(i32 %x, i32 %y) { + %b = add i32 %y, -1 + %cond = icmp eq i32 %x, 0 + %c = select i1 %cond, i32 %b, i32 %y + ret i32 %c +; CHECK: @test42 +; CHECK-NEXT: %cond = icmp eq i32 %x, 0 +; CHECK-NEXT: %b = sext i1 %cond to i32 +; CHECK-NEXT: %c = add i32 %b, %y +; CHECK-NEXT: ret i32 %c +} |
