Index: llvm/trunk/lib/Target/PowerPC/PPCPreEmitPeephole.cpp =================================================================== --- llvm/trunk/lib/Target/PowerPC/PPCPreEmitPeephole.cpp +++ llvm/trunk/lib/Target/PowerPC/PPCPreEmitPeephole.cpp @@ -18,6 +18,7 @@ #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/Statistic.h" #include "llvm/CodeGen/LivePhysRegs.h" +#include "llvm/CodeGen/MachineBasicBlock.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/CodeGen/MachineRegisterInfo.h" @@ -60,6 +61,7 @@ return false; bool Changed = false; const PPCInstrInfo *TII = MF.getSubtarget().getInstrInfo(); + const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo(); SmallVector InstrsToErase; for (MachineBasicBlock &MBB : MF) { for (MachineInstr &MI : MBB) { @@ -74,6 +76,75 @@ } } } + + // Eliminate conditional branch based on a constant CR bit by + // CRSET or CRUNSET. We eliminate the conditional branch or + // convert it into an unconditional branch. Also, if the CR bit + // is not used by other instructions, we eliminate CRSET as well. + auto I = MBB.getFirstInstrTerminator(); + if (I == MBB.instr_end()) + continue; + MachineInstr *Br = &*I; + if (Br->getOpcode() != PPC::BC && Br->getOpcode() != PPC::BCn) + continue; + MachineInstr *CRSetMI = nullptr; + unsigned CRBit = Br->getOperand(0).getReg(); + unsigned CRReg = getCRFromCRBit(CRBit); + bool SeenUse = false; + MachineBasicBlock::reverse_iterator It = Br, Er = MBB.rend(); + for (It++; It != Er; It++) { + if (It->modifiesRegister(CRBit, TRI)) { + if ((It->getOpcode() == PPC::CRUNSET || + It->getOpcode() == PPC::CRSET) && + It->getOperand(0).getReg() == CRBit) + CRSetMI = &*It; + break; + } + if (It->readsRegister(CRBit, TRI)) + SeenUse = true; + } + if (!CRSetMI) continue; + + unsigned CRSetOp = CRSetMI->getOpcode(); + if ((Br->getOpcode() == PPC::BCn && CRSetOp == PPC::CRSET) || + (Br->getOpcode() == PPC::BC && CRSetOp == PPC::CRUNSET)) { + // Remove this branch since it cannot be taken. + InstrsToErase.push_back(Br); + MBB.removeSuccessor(Br->getOperand(1).getMBB()); + } + else { + // This conditional branch is always taken. So, remove all branches + // and insert an unconditional branch to the destination of this. + MachineBasicBlock::iterator It = Br, Er = MBB.end(); + for (; It != Er && !SeenUse; It++) { + if (It->isDebugInstr()) continue; + assert(It->isTerminator() && "Non-terminator after a terminator"); + InstrsToErase.push_back(&*It); + } + if (!MBB.isLayoutSuccessor(Br->getOperand(1).getMBB())) { + ArrayRef NoCond; + TII->insertBranch(MBB, Br->getOperand(1).getMBB(), nullptr, + NoCond, Br->getDebugLoc()); + } + for (auto &Succ : MBB.successors()) + if (Succ != Br->getOperand(1).getMBB()) { + MBB.removeSuccessor(Succ); + break; + } + } + + // If the CRBit is not used by another instruction, we can eliminate + // CRSET/CRUNSET instruction. + if (!SeenUse) { + // We need to check use of the CRBit in successors. + for (auto &SuccMBB : MBB.successors()) + if (SuccMBB->isLiveIn(CRBit) || SuccMBB->isLiveIn(CRReg)) { + SeenUse = true; + break; + } + if (!SeenUse) + InstrsToErase.push_back(CRSetMI); + } } for (MachineInstr *MI : InstrsToErase) { LLVM_DEBUG(dbgs() << "PPC pre-emit peephole: erasing instruction: "); Index: llvm/trunk/test/CodeGen/PowerPC/setcr_bc.mir =================================================================== --- llvm/trunk/test/CodeGen/PowerPC/setcr_bc.mir +++ llvm/trunk/test/CodeGen/PowerPC/setcr_bc.mir @@ -0,0 +1,132 @@ +# RUN: llc -verify-machineinstrs -start-before=ppc-pre-emit-peephole %s -o - | FileCheck %s +--- | + target datalayout = "e-m:e-i64:64-n32:64" + target triple = "powerpc64le-unknown-linux-gnu" + + declare signext i32 @callee(i32 signext) local_unnamed_addr #1 + + define signext i32 @func(i32 signext %v) local_unnamed_addr #0 { + entry: + %call.i = tail call signext i32 @callee(i32 signext %v) + %tobool.i = icmp eq i32 %call.i, 0 + br i1 %tobool.i, label %if.else.i, label %if.then.i + + if.then.i: ; preds = %entry + %call2.i = tail call signext i32 @callee(i32 signext %call.i) + br label %_Z6calleei.exit + + if.else.i: ; preds = %entry + %phitmp = icmp sgt i32 %v, -1 + br label %_Z6calleei.exit + + _Z6calleei.exit: ; preds = %if.else.i, %if.then.i + %call2.i.sink = phi i32 [ %call2.i, %if.then.i ], [ %v, %if.else.i ] + %.sink = phi i1 [ false, %if.then.i ], [ %phitmp, %if.else.i ] + br i1 %.sink, label %if.end, label %if.then + + if.then: ; preds = %_Z6calleei.exit + %call1 = tail call signext i32 @callee(i32 signext 0) + br label %if.end + + if.end: ; preds = %if.then, %_Z6calleei.exit + ret i32 %call2.i.sink + } + + attributes #0 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="ppc64le" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+htm,+power8-vector,+vsx,-power9-vector,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" } + attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="ppc64le" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+htm,+power8-vector,+vsx,-power9-vector,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" } + +... +--- +name: func +alignment: 4 +exposesReturnsTwice: false +legalized: false +regBankSelected: false +selected: false +failedISel: false +tracksRegLiveness: true +registers: +liveins: + - { reg: '$x3', virtual-reg: '' } +frameInfo: + isFrameAddressTaken: false + isReturnAddressTaken: false + hasStackMap: false + hasPatchPoint: false + stackSize: 48 + offsetAdjustment: 0 + maxAlignment: 0 + adjustsStack: true + hasCalls: true + stackProtector: '' + maxCallFrameSize: 32 + hasOpaqueSPAdjustment: false + hasVAStart: false + hasMustTailInVarArgFunc: false + localFrameSize: 0 + savePoint: '' + restorePoint: '' +fixedStack: + - { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: 0, + callee-saved-register: '$x30', callee-saved-restored: true, debug-info-variable: '', + debug-info-expression: '', debug-info-location: '' } +stack: +constants: + +body: | + bb.0.entry: + successors: %bb.2(0x30000000), %bb.1(0x50000000) + liveins: $x3, $x30 + + ; bc and crxor (CRUNSET) should be removed. + ; CHECK-LABEL: func + ; CHECK: # %bb.1 + ; CHECK-NOT: crxor + ; CHECK-NOT: bc + ; CHECK: .LBB0_2 + + $x0 = MFLR8 implicit $lr8 + STD killed $x0, 16, $x1 + $x1 = STDU $x1, -48, $x1 + STD killed $x30, 32, $x1 :: (store 8 into %fixed-stack.0, align 16) + $x30 = OR8 $x3, $x3 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3 + renamable $cr0 = CMPLWI renamable $r3, 0 + BCC 76, killed renamable $cr0, %bb.2 + + bb.1.if.then.i: + successors: %bb.5(0x40000000), %bb.4(0x40000000) + liveins: $x3 + + renamable $x3 = EXTSW_32_64 killed renamable $r3, implicit $x3 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3 + renamable $cr0gt = CRUNSET implicit-def $cr0 + $x30 = OR8 killed $x3, $x3 + BC killed renamable $cr0gt, %bb.5 + + bb.4.if.then: + successors: %bb.5(0x80000000) + liveins: $x30 + + $x3 = LI8 0 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def dead $x3 + + bb.5.if.end: + liveins: $x30 + + renamable $x3 = EXTSW_32_64 killed renamable $r30, implicit $x30 + $x30 = LD 32, $x1 :: (load 8 from %fixed-stack.0, align 16) + $x1 = ADDI8 $x1, 48 + $x0 = LD 16, $x1 + MTLR8 killed $x0, implicit-def $lr8 + BLR8 implicit $lr8, implicit $rm, implicit killed $x3 + + bb.2.if.else.i: + successors: %bb.5(0x40000000), %bb.4(0x40000000) + liveins: $x30 + + renamable $cr0 = CMPWI renamable $r30, -1 + BCn killed renamable $cr0gt, %bb.4 + B %bb.5 + +... Index: llvm/trunk/test/CodeGen/PowerPC/setcr_bc2.mir =================================================================== --- llvm/trunk/test/CodeGen/PowerPC/setcr_bc2.mir +++ llvm/trunk/test/CodeGen/PowerPC/setcr_bc2.mir @@ -0,0 +1,132 @@ +# RUN: llc -verify-machineinstrs -start-before=ppc-pre-emit-peephole %s -o - | FileCheck %s +--- | + target datalayout = "e-m:e-i64:64-n32:64" + target triple = "powerpc64le-unknown-linux-gnu" + + declare signext i32 @callee(i32 signext) local_unnamed_addr #1 + + define signext i32 @func(i32 signext %v) local_unnamed_addr #0 { + entry: + %call.i = tail call signext i32 @callee(i32 signext %v) + %tobool.i = icmp eq i32 %call.i, 0 + br i1 %tobool.i, label %if.else.i, label %if.then.i + + if.then.i: ; preds = %entry + %call2.i = tail call signext i32 @callee(i32 signext %call.i) + br label %_Z6calleei.exit + + if.else.i: ; preds = %entry + %phitmp = icmp sgt i32 %v, -1 + br label %_Z6calleei.exit + + _Z6calleei.exit: ; preds = %if.else.i, %if.then.i + %call2.i.sink = phi i32 [ %call2.i, %if.then.i ], [ %v, %if.else.i ] + %.sink = phi i1 [ false, %if.then.i ], [ %phitmp, %if.else.i ] + br i1 %.sink, label %if.end, label %if.then + + if.then: ; preds = %_Z6calleei.exit + %call1 = tail call signext i32 @callee(i32 signext 0) + br label %if.end + + if.end: ; preds = %if.then, %_Z6calleei.exit + ret i32 %call2.i.sink + } + + attributes #0 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="ppc64le" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+htm,+power8-vector,+vsx,-power9-vector,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" } + attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="ppc64le" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+htm,+power8-vector,+vsx,-power9-vector,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" } + +... +--- +name: func +alignment: 4 +exposesReturnsTwice: false +legalized: false +regBankSelected: false +selected: false +failedISel: false +tracksRegLiveness: true +registers: +liveins: + - { reg: '$x3', virtual-reg: '' } +frameInfo: + isFrameAddressTaken: false + isReturnAddressTaken: false + hasStackMap: false + hasPatchPoint: false + stackSize: 48 + offsetAdjustment: 0 + maxAlignment: 0 + adjustsStack: true + hasCalls: true + stackProtector: '' + maxCallFrameSize: 32 + hasOpaqueSPAdjustment: false + hasVAStart: false + hasMustTailInVarArgFunc: false + localFrameSize: 0 + savePoint: '' + restorePoint: '' +fixedStack: + - { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: 0, + callee-saved-register: '$x30', callee-saved-restored: true, debug-info-variable: '', + debug-info-expression: '', debug-info-location: '' } +stack: +constants: + +body: | + bb.0.entry: + successors: %bb.2(0x30000000), %bb.1(0x50000000) + liveins: $x3, $x30 + + ; bc should be converted into b, but creqv (CRSET) should not be removed since it is used in a predecessor. + ; CHECK-LABEL: func + ; CHECK: # %bb.1 + ; CHECK: creqv + ; CHECK-NOT: bc + ; CHECK: .LBB0_2 + + $x0 = MFLR8 implicit $lr8 + STD killed $x0, 16, $x1 + $x1 = STDU $x1, -48, $x1 + STD killed $x30, 32, $x1 :: (store 8 into %fixed-stack.0, align 16) + $x30 = OR8 $x3, $x3 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3 + renamable $cr0 = CMPLWI renamable $r3, 0 + BCC 76, killed renamable $cr0, %bb.2 + + bb.1.if.then.i: + successors: %bb.5(0x40000000), %bb.4(0x40000000) + liveins: $x3 + + renamable $x3 = EXTSW_32_64 killed renamable $r3, implicit $x3 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def $x3 + renamable $cr0gt = CRSET implicit-def $cr0 + $x30 = OR8 killed $x3, $x3 + BC killed renamable $cr0gt, %bb.5 + + bb.4.if.then: + successors: %bb.5(0x80000000) + liveins: $x30 + + $x3 = LI8 0 + BL8_NOP @callee, csr_svr464_altivec, implicit-def dead $lr8, implicit $rm, implicit killed $x3, implicit $x2, implicit-def $r1, implicit-def dead $x3 + + bb.5.if.end: + liveins: $x30, $cr0gt + + renamable $x3 = EXTSW_32_64 killed renamable $r30, implicit $x30 + $x30 = LD 32, $x1 :: (load 8 from %fixed-stack.0, align 16) + $x1 = ADDI8 $x1, 48 + $x0 = LD 16, $x1 + MTLR8 killed $x0, implicit-def $lr8 + BLR8 implicit $lr8, implicit $rm, implicit killed $x3 + + bb.2.if.else.i: + successors: %bb.5(0x40000000), %bb.4(0x40000000) + liveins: $x30 + + renamable $cr0 = CMPWI renamable $r30, -1 + BCn killed renamable $cr0gt, %bb.4 + B %bb.5 + +...