[llvm] r281113 - X86: Fold tail calls into conditional branches also for 64-bit (PR26302)
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Mon Sep 12 10:19:30 PDT 2016
Thanks for fixing, and sorry for the breakage. Your fix looks good to me.
Cheers,
Hans
On Mon, Sep 12, 2016 at 9:16 AM, Ahmed Bougacha via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Hey Hans,
>
> In r281223, I fixed an issue where the new TCRETURNdi64cc didn't get
> the parameter register implicit-uses. I'd appreciate a second look!
>
> Thanks,
> -Ahmed
>
>
> On Fri, Sep 9, 2016 at 3:37 PM, Hans Wennborg via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Author: hans
>> Date: Fri Sep 9 17:37:27 2016
>> New Revision: 281113
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=281113&view=rev
>> Log:
>> X86: Fold tail calls into conditional branches also for 64-bit (PR26302)
>>
>> This extends the optimization in r280832 to also work for 64-bit. The only
>> quirk is that we can't do this for 64-bit Windows (yet).
>>
>> Differential Revision: https://reviews.llvm.org/D24423
>>
>> Modified:
>> llvm/trunk/lib/Target/X86/X86ExpandPseudo.cpp
>> llvm/trunk/lib/Target/X86/X86InstrControl.td
>> llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
>> llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
>> llvm/trunk/test/CodeGen/X86/conditional-tailcall.ll
>> llvm/trunk/test/CodeGen/X86/shrink-compare.ll
>>
>> Modified: llvm/trunk/lib/Target/X86/X86ExpandPseudo.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ExpandPseudo.cpp?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86ExpandPseudo.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86ExpandPseudo.cpp Fri Sep 9 17:37:27 2016
>> @@ -81,6 +81,7 @@ bool X86ExpandPseudo::ExpandMI(MachineBa
>> case X86::TCRETURNri:
>> case X86::TCRETURNmi:
>> case X86::TCRETURNdi64:
>> + case X86::TCRETURNdi64cc:
>> case X86::TCRETURNri64:
>> case X86::TCRETURNmi64: {
>> bool isMem = Opcode == X86::TCRETURNmi || Opcode == X86::TCRETURNmi64;
>> @@ -98,7 +99,7 @@ bool X86ExpandPseudo::ExpandMI(MachineBa
>> Offset = StackAdj - MaxTCDelta;
>> assert(Offset >= 0 && "Offset should never be negative");
>>
>> - if (Opcode == X86::TCRETURNdicc) {
>> + if (Opcode == X86::TCRETURNdicc || Opcode == X86::TCRETURNdi64cc) {
>> assert(Offset == 0 && "Conditional tail call cannot adjust the stack.");
>> }
>>
>> @@ -111,7 +112,7 @@ bool X86ExpandPseudo::ExpandMI(MachineBa
>> // Jump to label or value in register.
>> bool IsWin64 = STI->isTargetWin64();
>> if (Opcode == X86::TCRETURNdi || Opcode == X86::TCRETURNdicc ||
>> - Opcode == X86::TCRETURNdi64) {
>> + Opcode == X86::TCRETURNdi64 || Opcode == X86::TCRETURNdi64cc) {
>> unsigned Op;
>> switch (Opcode) {
>> case X86::TCRETURNdi:
>> @@ -120,6 +121,11 @@ bool X86ExpandPseudo::ExpandMI(MachineBa
>> case X86::TCRETURNdicc:
>> Op = X86::TAILJMPd_CC;
>> break;
>> + case X86::TCRETURNdi64cc:
>> + assert(!IsWin64 && "Conditional tail calls confuse the Win64 unwinder.");
>> + // TODO: We could do it for Win64 "leaf" functions though; PR30337.
>> + Op = X86::TAILJMPd64_CC;
>> + break;
>> default:
>> // Note: Win64 uses REX prefixes indirect jumps out of functions, but
>> // not direct ones.
>> @@ -135,7 +141,7 @@ bool X86ExpandPseudo::ExpandMI(MachineBa
>> MIB.addExternalSymbol(JumpTarget.getSymbolName(),
>> JumpTarget.getTargetFlags());
>> }
>> - if (Op == X86::TAILJMPd_CC) {
>> + if (Op == X86::TAILJMPd_CC || Op == X86::TAILJMPd64_CC) {
>> MIB.addImm(MBBI->getOperand(2).getImm());
>> }
>>
>>
>> Modified: llvm/trunk/lib/Target/X86/X86InstrControl.td
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrControl.td?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86InstrControl.td (original)
>> +++ llvm/trunk/lib/Target/X86/X86InstrControl.td Fri Sep 9 17:37:27 2016
>> @@ -305,17 +305,27 @@ let isCall = 1, Uses = [RSP], SchedRW =
>> let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1,
>> isCodeGenOnly = 1, Uses = [RSP], usesCustomInserter = 1,
>> SchedRW = [WriteJump] in {
>> - def TCRETURNdi64 : PseudoI<(outs),
>> - (ins i64i32imm_pcrel:$dst, i32imm:$offset),
>> - []>;
>> - def TCRETURNri64 : PseudoI<(outs),
>> - (ins ptr_rc_tailcall:$dst, i32imm:$offset), []>;
>> + def TCRETURNdi64 : PseudoI<(outs),
>> + (ins i64i32imm_pcrel:$dst, i32imm:$offset),
>> + []>;
>> + def TCRETURNdi64cc : PseudoI<(outs),
>> + (ins i64i32imm_pcrel:$dst, i32imm:$offset,
>> + i32imm:$cond), []>;
>> + def TCRETURNri64 : PseudoI<(outs),
>> + (ins ptr_rc_tailcall:$dst, i32imm:$offset), []>;
>> let mayLoad = 1 in
>> - def TCRETURNmi64 : PseudoI<(outs),
>> - (ins i64mem_TC:$dst, i32imm:$offset), []>;
>> + def TCRETURNmi64 : PseudoI<(outs),
>> + (ins i64mem_TC:$dst, i32imm:$offset), []>;
>>
>> def TAILJMPd64 : Ii32PCRel<0xE9, RawFrm, (outs), (ins i64i32imm_pcrel:$dst),
>> "jmp\t$dst", [], IIC_JMP_REL>;
>> +
>> + // This gets substituted to a conditional jump instruction in MC lowering.
>> + def TAILJMPd64_CC : Ii32PCRel<0x80, RawFrm, (outs),
>> + (ins i64i32imm_pcrel:$dst, i32imm:$cond),
>> + "",
>> + [], IIC_JMP_REL>;
>> +
>> def TAILJMPr64 : I<0xFF, MRM4r, (outs), (ins ptr_rc_tailcall:$dst),
>> "jmp{q}\t{*}$dst", [], IIC_JMP_MEM>;
>>
>>
>> Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.cpp?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Fri Sep 9 17:37:27 2016
>> @@ -4101,11 +4101,18 @@ bool X86InstrInfo::isUnconditionalTailCa
>> bool X86InstrInfo::canMakeTailCallConditional(
>> SmallVectorImpl<MachineOperand> &BranchCond,
>> const MachineInstr &TailCall) const {
>> - if (TailCall.getOpcode() != X86::TCRETURNdi) {
>> + if (TailCall.getOpcode() != X86::TCRETURNdi &&
>> + TailCall.getOpcode() != X86::TCRETURNdi64) {
>> // Only direct calls can be done with a conditional branch.
>> return false;
>> }
>>
>> + if (Subtarget.isTargetWin64()) {
>> + // Conditional tail calls confuse the Win64 unwinder.
>> + // TODO: Allow them for "leaf" functions; PR30337.
>> + return false;
>> + }
>> +
>> assert(BranchCond.size() == 1);
>> if (BranchCond[0].getImm() > X86::LAST_VALID_COND) {
>> // Can't make a conditional tail call with this condition.
>> @@ -4144,7 +4151,10 @@ void X86InstrInfo::replaceBranchWithTail
>> break;
>> }
>>
>> - auto MIB = BuildMI(MBB, I, MBB.findDebugLoc(I), get(X86::TCRETURNdicc));
>> + unsigned Opc = TailCall.getOpcode() == X86::TCRETURNdi ? X86::TCRETURNdicc
>> + : X86::TCRETURNdi64cc;
>> +
>> + auto MIB = BuildMI(MBB, I, MBB.findDebugLoc(I), get(Opc));
>> MIB->addOperand(TailCall.getOperand(0)); // Destination.
>> MIB.addImm(0); // Stack offset (not used).
>> MIB->addOperand(BranchCond[0]); // Condition.
>>
>> Modified: llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86MCInstLower.cpp?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86MCInstLower.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86MCInstLower.cpp Fri Sep 9 17:37:27 2016
>> @@ -505,6 +505,7 @@ ReSimplify:
>> case X86::TAILJMPd:
>> case X86::TAILJMPd64: Opcode = X86::JMP_1; goto SetTailJmpOpcode;
>> case X86::TAILJMPd_CC:
>> + case X86::TAILJMPd64_CC:
>> Opcode = X86::GetCondBranchFromCond(
>> static_cast<X86::CondCode>(MI->getOperand(1).getImm()));
>> goto SetTailJmpOpcode;
>> @@ -1309,6 +1310,7 @@ void X86AsmPrinter::EmitInstruction(cons
>> case X86::TAILJMPr64:
>> case X86::TAILJMPm64:
>> case X86::TAILJMPd64:
>> + case X86::TAILJMPd64_CC:
>> case X86::TAILJMPr64_REX:
>> case X86::TAILJMPm64_REX:
>> // Lower these as normal, but add some comments.
>>
>> Modified: llvm/trunk/test/CodeGen/X86/conditional-tailcall.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/conditional-tailcall.ll?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/conditional-tailcall.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/conditional-tailcall.ll Fri Sep 9 17:37:27 2016
>> @@ -1,4 +1,5 @@
>> ; RUN: llc < %s -mtriple=i686-linux -show-mc-encoding | FileCheck %s
>> +; RUN: llc < %s -mtriple=x86_64-linux -show-mc-encoding | FileCheck %s
>>
>> declare void @foo()
>> declare void @bar()
>>
>> Modified: llvm/trunk/test/CodeGen/X86/shrink-compare.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/shrink-compare.ll?rev=281113&r1=281112&r2=281113&view=diff
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/shrink-compare.ll (original)
>> +++ llvm/trunk/test/CodeGen/X86/shrink-compare.ll Fri Sep 9 17:37:27 2016
>> @@ -1,4 +1,4 @@
>> -; RUN: llc < %s -march=x86-64 | FileCheck %s
>> +; RUN: llc < %s -mtriple=x86_64-linux | FileCheck %s
>>
>> declare void @bar()
>>
>> @@ -93,7 +93,7 @@ if.end:
>> ; CHECK-LABEL: test2_1:
>> ; CHECK: movzbl
>> ; CHECK: cmpl $256
>> -; CHECK: jne
>> +; CHECK: je bar
>> define void @test2_1(i32 %X) nounwind minsize {
>> entry:
>> %and = and i32 %X, 255
>> @@ -223,7 +223,7 @@ if.end:
>> ; CHECK-LABEL: test_sext_i8_icmp_255:
>> ; CHECK: movb $1,
>> ; CHECK: testb
>> -; CHECK: jne
>> +; CHECK: je bar
>> define void @test_sext_i8_icmp_255(i8 %x) nounwind minsize {
>> entry:
>> %sext = sext i8 %x to i32
>>
>>
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