diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 6 | ||||
| -rw-r--r-- | test/CodeGen/X86/2008-12-22-dagcombine-5.ll | 14 |
2 files changed, 20 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 783bfce9cc..e3525df181 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1184,6 +1184,12 @@ SDValue DAGCombiner::visitSUB(SDNode *N) { N0.getOperand(1).getOperand(0) == N1) return DAG.getNode(ISD::SUB, VT, N0.getOperand(0), N0.getOperand(1).getOperand(1)); + // fold ((A-(B-C))-C) -> A-B + if (N0.getOpcode() == ISD::SUB && + N0.getOperand(1).getOpcode() == ISD::SUB && + N0.getOperand(1).getOperand(1) == N1) + return DAG.getNode(ISD::SUB, VT, N0.getOperand(0), + N0.getOperand(1).getOperand(0)); // fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c)) if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) { SDValue Result = combineSelectAndUse(N, N1, N0, DAG, TLI, LegalOperations); diff --git a/test/CodeGen/X86/2008-12-22-dagcombine-5.ll b/test/CodeGen/X86/2008-12-22-dagcombine-5.ll new file mode 100644 index 0000000000..24be521842 --- /dev/null +++ b/test/CodeGen/X86/2008-12-22-dagcombine-5.ll @@ -0,0 +1,14 @@ +; RUN: llvm-as < %s | llc -march=x86 | grep "(%esp)" | count 2 +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" +target triple = "i386-apple-darwin9.5" +; -(-a) - a should be found and removed, leaving refs to only L and P +define i32 @test(i32 %a, i32 %L, i32 %P) nounwind { +entry: + %0 = sub i32 %L, %a + %1 = sub i32 %P, %0 + %2 = sub i32 %1, %a + br label %return + +return: ; preds = %bb3 + ret i32 %2 +} |