diff --git a/llvm/include/llvm/CodeGen/TargetLowering.h b/llvm/include/llvm/CodeGen/TargetLowering.h index 69ae4f80297d5..84c53e1e45452 100644 --- a/llvm/include/llvm/CodeGen/TargetLowering.h +++ b/llvm/include/llvm/CodeGen/TargetLowering.h @@ -5795,6 +5795,8 @@ class LLVM_ABI TargetLowering : public TargetLoweringBase { private: SDValue foldSetCCWithAnd(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond, const SDLoc &DL, DAGCombinerInfo &DCI) const; + SDValue foldSetCCWithOr(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond, + const SDLoc &DL, DAGCombinerInfo &DCI) const; SDValue foldSetCCWithBinOp(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond, const SDLoc &DL, DAGCombinerInfo &DCI) const; diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 977579e851e33..000f8cc6786a5 100644 --- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -21,6 +21,7 @@ #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineJumpTableInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/SDPatternMatch.h" #include "llvm/CodeGen/SelectionDAG.h" #include "llvm/CodeGen/TargetRegisterInfo.h" #include "llvm/IR/DataLayout.h" @@ -37,6 +38,7 @@ #include #include using namespace llvm; +using namespace llvm::SDPatternMatch; /// NOTE: The TargetMachine owns TLOF. TargetLowering::TargetLowering(const TargetMachine &tm) @@ -4227,6 +4229,42 @@ SDValue TargetLowering::foldSetCCWithAnd(EVT VT, SDValue N0, SDValue N1, return SDValue(); } +/// This helper function of SimplifySetCC tries to optimize the comparison when +/// either operand of the SetCC node is a bitwise-or instruction. +/// For now, this just transforms (X | Y) ==/!= Y into X & ~Y ==/!= 0. +SDValue TargetLowering::foldSetCCWithOr(EVT VT, SDValue N0, SDValue N1, + ISD::CondCode Cond, const SDLoc &DL, + DAGCombinerInfo &DCI) const { + if (N1.getOpcode() == ISD::OR && N0.getOpcode() != ISD::OR) + std::swap(N0, N1); + + SelectionDAG &DAG = DCI.DAG; + EVT OpVT = N0.getValueType(); + if (!N0.hasOneUse() || !OpVT.isInteger() || + (Cond != ISD::SETEQ && Cond != ISD::SETNE)) + return SDValue(); + + // (X | Y) == Y + // (X | Y) != Y + SDValue X; + if (sd_match(N0, m_Or(m_Value(X), m_Specific(N1))) && hasAndNotCompare(N1)) { + // If the target supports an 'and-not' or 'and-complement' logic operation, + // try to use that to make a comparison operation more efficient. + + // Bail out if the compare operand that we want to turn into a zero is + // already a zero (otherwise, infinite loop). + if (isNullConstant(N1)) + return SDValue(); + + // Transform this into: X & ~Y ==/!= 0. + SDValue NotY = DAG.getNOT(SDLoc(N1), N1, OpVT); + SDValue NewAnd = DAG.getNode(ISD::AND, SDLoc(N0), OpVT, X, NotY); + return DAG.getSetCC(DL, VT, NewAnd, DAG.getConstant(0, DL, OpVT), Cond); + } + + return SDValue(); +} + /// There are multiple IR patterns that could be checking whether certain /// truncation of a signed number would be lossy or not. The pattern which is /// best at IR level, may not lower optimally. Thus, we want to unfold it. @@ -5522,6 +5560,9 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1, if (SDValue V = foldSetCCWithAnd(VT, N0, N1, Cond, dl, DCI)) return V; + + if (SDValue V = foldSetCCWithOr(VT, N0, N1, Cond, dl, DCI)) + return V; } // Fold remainder of division by a constant. diff --git a/llvm/test/CodeGen/AArch64/aarch64-bitwisenot-fold.ll b/llvm/test/CodeGen/AArch64/aarch64-bitwisenot-fold.ll index 5fbf38b2560d4..d6401f347f277 100644 --- a/llvm/test/CodeGen/AArch64/aarch64-bitwisenot-fold.ll +++ b/llvm/test/CodeGen/AArch64/aarch64-bitwisenot-fold.ll @@ -96,3 +96,51 @@ define i64 @andnot_sub_with_neg_i64(i64 %a0, i64 %a1) { %and = and i64 %diff, %a0 ret i64 %and } + +define i32 @and_not_select_eq(i32 %a, i32 %b, i32 %c) { +; CHECK-LABEL: and_not_select_eq: +; CHECK: // %bb.0: +; CHECK-NEXT: bics wzr, w1, w0 +; CHECK-NEXT: csel w0, w0, w2, eq +; CHECK-NEXT: ret + %or = or i32 %b, %a + %cmp = icmp eq i32 %or, %a + %a.c = select i1 %cmp, i32 %a, i32 %c + ret i32 %a.c +} + +define i32 @and_not_select_ne(i32 %a, i32 %b, i32 %c) { +; CHECK-LABEL: and_not_select_ne: +; CHECK: // %bb.0: +; CHECK-NEXT: bics wzr, w1, w0 +; CHECK-NEXT: csel w0, w0, w2, ne +; CHECK-NEXT: ret + %or = or i32 %b, %a + %cmp = icmp ne i32 %or, %a + %a.c = select i1 %cmp, i32 %a, i32 %c + ret i32 %a.c +} + +define i32 @and_not_select_eq_swap(i32 %a, i32 %b, i32 %c) { +; CHECK-LABEL: and_not_select_eq_swap: +; CHECK: // %bb.0: +; CHECK-NEXT: bics wzr, w1, w0 +; CHECK-NEXT: csel w0, w0, w2, eq +; CHECK-NEXT: ret + %or = or i32 %b, %a + %cmp = icmp eq i32 %a, %or + %a.c = select i1 %cmp, i32 %a, i32 %c + ret i32 %a.c +} + +define i32 @and_not_select_ne_swap(i32 %a, i32 %b, i32 %c) { +; CHECK-LABEL: and_not_select_ne_swap: +; CHECK: // %bb.0: +; CHECK-NEXT: bics wzr, w1, w0 +; CHECK-NEXT: csel w0, w0, w2, ne +; CHECK-NEXT: ret + %or = or i32 %a, %b + %cmp = icmp ne i32 %a, %or + %a.c = select i1 %cmp, i32 %a, i32 %c + ret i32 %a.c +} diff --git a/llvm/test/CodeGen/AArch64/switch-cases-to-branch-and.ll b/llvm/test/CodeGen/AArch64/switch-cases-to-branch-and.ll index 4d36a003cbfe4..e99ba4843c452 100644 --- a/llvm/test/CodeGen/AArch64/switch-cases-to-branch-and.ll +++ b/llvm/test/CodeGen/AArch64/switch-cases-to-branch-and.ll @@ -569,8 +569,7 @@ define void @test_successor_with_loop_phi(ptr %A, ptr %B) { ; CHECK-NEXT: ldr w8, [x0] ; CHECK-NEXT: str wzr, [x0] ; CHECK-NEXT: mov x0, x1 -; CHECK-NEXT: orr w8, w8, #0x4 -; CHECK-NEXT: cmp w8, #4 +; CHECK-NEXT: tst w8, #0xfffffffb ; CHECK-NEXT: b.eq LBB7_1 ; CHECK-NEXT: ; %bb.2: ; %exit ; CHECK-NEXT: ret