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Win64: Don't use REX prefix for direct tail calls 

The REX prefix should be used on indirect jmps, but not direct ones.
For direct jumps, the unwinder looks at the offset to determine if
it's inside the current function.

Differential Revision: https://reviews.llvm.org/D24359

llvm-svn: 281003
This commit is contained in:
Hans Wennborg 2016-09-08 23:35:10 +00:00
parent f205a274c4
commit c39ef776fc
9 changed files with 8 additions and 12 deletions
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4
llvm/lib/Target/X86/X86ExpandPseudo.cpp
View File

@ -121,7 +121,9 @@ bool X86ExpandPseudo::ExpandMI(MachineBasicBlock &MBB,
Op = X86::TAILJMPd_CC;
break;
default:
Op = IsWin64 ? X86::TAILJMPd64_REX : X86::TAILJMPd64;
// Note: Win64 uses REX prefixes indirect jumps out of functions, but
// not direct ones.
Op = X86::TAILJMPd64;
break;
}
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(Op));

1
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -24521,7 +24521,6 @@ X86TargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
case X86::TAILJMPd64:
case X86::TAILJMPr64:
case X86::TAILJMPm64:
case X86::TAILJMPd64_REX:
case X86::TAILJMPr64_REX:
case X86::TAILJMPm64_REX:
llvm_unreachable("TAILJMP64 would not be touched here.");

5
llvm/lib/Target/X86/X86InstrControl.td
View File

@ -323,11 +323,8 @@ let isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1,
def TAILJMPm64 : I<0xFF, MRM4m, (outs), (ins i64mem_TC:$dst),
"jmp{q}\t{*}$dst", [], IIC_JMP_MEM>;
// Win64 wants jumps leaving the function to have a REX_W prefix.
// Win64 wants indirect jumps leaving the function to have a REX_W prefix.
let hasREX_WPrefix = 1 in {
def TAILJMPd64_REX : Ii32PCRel<0xE9, RawFrm, (outs),
(ins i64i32imm_pcrel:$dst),
"rex64 jmp\t$dst", [], IIC_JMP_REL>;
def TAILJMPr64_REX : I<0xFF, MRM4r, (outs), (ins ptr_rc_tailcall:$dst),
"rex64 jmp{q}\t{*}$dst", [], IIC_JMP_MEM>;

1
llvm/lib/Target/X86/X86InstrInfo.cpp
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@ -8286,7 +8286,6 @@ bool X86InstrInfo::isTailCall(const MachineInstr &Inst) const {
case X86::TAILJMPd64:
case X86::TAILJMPm64:
case X86::TAILJMPr64:
case X86::TAILJMPd64_REX:
case X86::TAILJMPm64_REX:
case X86::TAILJMPr64_REX:
return true;

1
llvm/lib/Target/X86/X86MCInstLower.cpp
View File

@ -1311,7 +1311,6 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
case X86::TAILJMPd64:
case X86::TAILJMPr64_REX:
case X86::TAILJMPm64_REX:
case X86::TAILJMPd64_REX:
// Lower these as normal, but add some comments.
OutStreamer->AddComment("TAILCALL");
break;

2
llvm/test/CodeGen/X86/seh-catchpad.ll
View File

@ -173,7 +173,7 @@ entry:
; CHECK: "?filt$0@0@main@@": # @"\01?filt$0@0@main@@"
; CHECK: .seh_proc "?filt$0@0@main@@"
; CHECK: .seh_endprologue
; CHECK: rex64 jmp filt # TAILCALL
; CHECK: jmp filt # TAILCALL
; CHECK: .seh_handlerdata
declare i32 @filt() #1

2
llvm/test/CodeGen/X86/tail-call-win64.ll
View File

@ -22,7 +22,7 @@ define void @tail_jmp_imm() {
}
; CHECK-LABEL: tail_jmp_imm:
; CHECK: rex64 jmp tail_tgt
; CHECK: jmp tail_tgt
@g_fptr = global void ()* @tail_tgt

2
llvm/test/CodeGen/X86/win64_sibcall.ll
View File

@ -21,7 +21,7 @@ entry:
; WIN_X64: xorl %r8d, %r8d
; WIN_X64: popq %rax
; WIN_X64: rex64 jmp C2 # TAILCALL
; WIN_X64: jmp C2 # TAILCALL
; LINUX: xorl %edx, %edx
; LINUX: jmp C2 # TAILCALL

2
llvm/test/DebugInfo/COFF/register-variables.ll
View File

@ -54,7 +54,7 @@
; ASM: addq $32, %rsp
; ASM: popq %rsi
; ASM: [[func_end:\.Ltmp.*]]:
; ASM: rex64 jmp putint # TAILCALL
; ASM: jmp putint # TAILCALL
; ASM: .short 4414 # Record kind: S_LOCAL
; ASM: .asciz "p"