[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
Fri Sep 9 15:37:28 PDT 2016
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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