Index: llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp =================================================================== --- llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp +++ llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.cpp @@ -1715,38 +1715,47 @@ else if (MI->getParent() != CmpInstr.getParent()) return false; else if (Value != 0) { - // The record-form instructions set CR bit based on signed comparison against 0. - // We try to convert a compare against 1 or -1 into a compare against 0. - bool Success = false; - if (!equalityOnly && MRI->hasOneUse(CRReg)) { - MachineInstr *UseMI = &*MRI->use_instr_begin(CRReg); - if (UseMI->getOpcode() == PPC::BCC) { - PPC::Predicate Pred = (PPC::Predicate)UseMI->getOperand(0).getImm(); - unsigned PredCond = PPC::getPredicateCondition(Pred); - unsigned PredHint = PPC::getPredicateHint(Pred); - int16_t Immed = (int16_t)Value; + // The record-form instructions set CR bit based on signed comparison + // against 0. We try to convert a compare against 1 or -1 into a compare + // against 0 to exploit record-form instructions. For example, we change + // the condition "greater than -1" into "greater than or equal to 0" + // and "less than 1" into "less than or equal to 0". + + // Since we optimize comparison based on a specific branch condition, + // we don't optimize if condition code is used by more than once. + if (equalityOnly || !MRI->hasOneUse(CRReg)) + return false; - // When modyfing the condition in the predicate, we propagate hint bits - // from the original predicate to the new one. - if (Immed == -1 && PredCond == PPC::PRED_GT) { - // We convert "greater than -1" into "greater than or equal to 0", - // since we are assuming signed comparison by !equalityOnly - PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)), - PPC::getPredicate(PPC::PRED_GE, PredHint))); - Success = true; - } - else if (Immed == 1 && PredCond == PPC::PRED_LT) { - // We convert "less than 1" into "less than or equal to 0". - PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)), - PPC::getPredicate(PPC::PRED_LE, PredHint))); - Success = true; - } - } - } + MachineInstr *UseMI = &*MRI->use_instr_begin(CRReg); + if (UseMI->getOpcode() != PPC::BCC) + return false; - // PPC does not have a record-form SUBri. - if (!Success) + PPC::Predicate Pred = (PPC::Predicate)UseMI->getOperand(0).getImm(); + PPC::Predicate NewPred = Pred; + unsigned PredCond = PPC::getPredicateCondition(Pred); + unsigned PredHint = PPC::getPredicateHint(Pred); + int16_t Immed = (int16_t)Value; + + // When modyfing the condition in the predicate, we propagate hint bits + // from the original predicate to the new one. + if (Immed == -1 && PredCond == PPC::PRED_GT) + // We convert "greater than -1" into "greater than or equal to 0", + // since we are assuming signed comparison by !equalityOnly + NewPred = PPC::getPredicate(PPC::PRED_GE, PredHint); + else if (Immed == -1 && PredCond == PPC::PRED_LE) + // We convert "less than or equal to -1" into "less than 0". + NewPred = PPC::getPredicate(PPC::PRED_LT, PredHint); + else if (Immed == 1 && PredCond == PPC::PRED_LT) + // We convert "less than 1" into "less than or equal to 0". + NewPred = PPC::getPredicate(PPC::PRED_LE, PredHint); + else if (Immed == 1 && PredCond == PPC::PRED_GE) + // We convert "greater than or equal to 1" into "greater than 0". + NewPred = PPC::getPredicate(PPC::PRED_GT, PredHint); + else return false; + + PredsToUpdate.push_back(std::make_pair(&(UseMI->getOperand(0)), + NewPred)); } // Search for Sub. Index: llvm/trunk/test/CodeGen/PowerPC/opt-cmp-inst-cr0-live.ll =================================================================== --- llvm/trunk/test/CodeGen/PowerPC/opt-cmp-inst-cr0-live.ll +++ llvm/trunk/test/CodeGen/PowerPC/opt-cmp-inst-cr0-live.ll @@ -1,4 +1,5 @@ ; RUN: llc -verify-machineinstrs -print-before=peephole-opt -print-after=peephole-opt -mtriple=powerpc64-unknown-linux-gnu -o /dev/null 2>&1 < %s | FileCheck %s +; RUN: llc -verify-machineinstrs -print-before=peephole-opt -print-after=peephole-opt -mtriple=powerpc64le-unknown-linux-gnu -o /dev/null 2>&1 < %s | FileCheck %s ; CHECK-LABEL: fn1 define signext i32 @fn1(i32 %baz) { @@ -99,3 +100,38 @@ bar: ret i32 0 } + +; This test confirms record-form instructions are emitted for comparison +; against a non-zero value. + +; CHECK-LABEL: fn6 +define i8* @fn6(i8* readonly %p) { +; CHECK: LBZU +; CHECK: EXTSBo +; CHECK-NOT: CMP +; CHECK: BCC +; CHECK: LBZU +; CHECK: EXTSBo +; CHECK-NOT: CMP +; CHECK: BCC + +entry: + %incdec.ptr = getelementptr inbounds i8, i8* %p, i64 -1 + %0 = load i8, i8* %incdec.ptr + %cmp = icmp sgt i8 %0, -1 + br i1 %cmp, label %out, label %if.end + +if.end: + %incdec.ptr2 = getelementptr inbounds i8, i8* %p, i64 -2 + %1 = load i8, i8* %incdec.ptr2 + %cmp4 = icmp sgt i8 %1, -1 + br i1 %cmp4, label %out, label %cleanup + +out: + %p.addr.0 = phi i8* [ %incdec.ptr, %entry ], [ %incdec.ptr2, %if.end ] + br label %cleanup + +cleanup: + %retval.0 = phi i8* [ %p.addr.0, %out ], [ null, %if.end ] + ret i8* %retval.0 +}