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MC/X86: Implement custom lowering to make sure we match things like

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X86::ADC32ri $0, %eax
to
  X86::ADC32i32 $0

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104030 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2010-05-18 17:22:24 +00:00
parent 3538c808f8
commit 3f40b31256
2 changed files with 94 additions and 0 deletions
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68
lib/Target/X86/AsmPrinter/X86MCInstLower.cpp
View File

@ -224,6 +224,26 @@ static void LowerUnaryToTwoAddr(MCInst &OutMI, unsigned NewOpc) {
OutMI.addOperand(OutMI.getOperand(0)); OutMI.addOperand(OutMI.getOperand(0));
} }
/// \brief Simplify FOO $imm, %{al,ax,eax,rax} to FOO $imm, for instruction with
/// a short fixed-register form.
static void SimplifyShortImmForm(MCInst &Inst, unsigned Opcode) {
unsigned ImmOp = Inst.getNumOperands() - 1;
assert(Inst.getOperand(0).isReg() && Inst.getOperand(ImmOp).isImm() &&
((Inst.getNumOperands() == 3 && Inst.getOperand(1).isReg() &&
Inst.getOperand(0).getReg() == Inst.getOperand(1).getReg()) ||
Inst.getNumOperands() == 2) && "Unexpected instruction!");
// Check whether the destination register can be fixed.
unsigned Reg = Inst.getOperand(0).getReg();
if (Reg != X86::AL && Reg != X86::AX && Reg != X86::EAX && Reg != X86::RAX)
return;
// If so, rewrite the instruction.
MCInst New;
New.setOpcode(Opcode);
New.addOperand(Inst.getOperand(ImmOp));
Inst = New;
}
void X86MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const { void X86MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
OutMI.setOpcode(MI->getOpcode()); OutMI.setOpcode(MI->getOpcode());
@ -332,6 +352,54 @@ void X86MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
case X86::JGE_4: OutMI.setOpcode(X86::JGE_1); break; case X86::JGE_4: OutMI.setOpcode(X86::JGE_1); break;
case X86::JLE_4: OutMI.setOpcode(X86::JLE_1); break; case X86::JLE_4: OutMI.setOpcode(X86::JLE_1); break;
case X86::JG_4: OutMI.setOpcode(X86::JG_1); break; case X86::JG_4: OutMI.setOpcode(X86::JG_1); break;
// We don't currently select the correct instruction form for instructions
// which have a short %eax, etc. form. Handle this by custom lowering, for
// now.
//
// Note, we are currently not handling the following instructions:
// MOV8ao8, MOV8o8a
// MOV16ao16, MOV16o16a
// MOV32ao32, MOV32o32a
// MOV64ao64, MOV64ao8
// MOV64o64a, MOV64o8a
// XCHG16ar, XCHG32ar, XCHG64ar
case X86::ADC8ri: SimplifyShortImmForm(OutMI, X86::ADC8i8); break;
case X86::ADC16ri: SimplifyShortImmForm(OutMI, X86::ADC16i16); break;
case X86::ADC32ri: SimplifyShortImmForm(OutMI, X86::ADC32i32); break;
case X86::ADC64ri32: SimplifyShortImmForm(OutMI, X86::ADC64i32); break;
case X86::ADD8ri: SimplifyShortImmForm(OutMI, X86::ADD8i8); break;
case X86::ADD16ri: SimplifyShortImmForm(OutMI, X86::ADD16i16); break;
case X86::ADD32ri: SimplifyShortImmForm(OutMI, X86::ADD32i32); break;
case X86::ADD64ri32: SimplifyShortImmForm(OutMI, X86::ADD64i32); break;
case X86::AND8ri: SimplifyShortImmForm(OutMI, X86::AND8i8); break;
case X86::AND16ri: SimplifyShortImmForm(OutMI, X86::AND16i16); break;
case X86::AND32ri: SimplifyShortImmForm(OutMI, X86::AND32i32); break;
case X86::AND64ri32: SimplifyShortImmForm(OutMI, X86::AND64i32); break;
case X86::CMP8ri: SimplifyShortImmForm(OutMI, X86::CMP8i8); break;
case X86::CMP16ri: SimplifyShortImmForm(OutMI, X86::CMP16i16); break;
case X86::CMP32ri: SimplifyShortImmForm(OutMI, X86::CMP32i32); break;
case X86::CMP64ri32: SimplifyShortImmForm(OutMI, X86::CMP64i32); break;
case X86::OR8ri: SimplifyShortImmForm(OutMI, X86::OR8i8); break;
case X86::OR16ri: SimplifyShortImmForm(OutMI, X86::OR16i16); break;
case X86::OR32ri: SimplifyShortImmForm(OutMI, X86::OR32i32); break;
case X86::OR64ri32: SimplifyShortImmForm(OutMI, X86::OR64i32); break;
case X86::SBB8ri: SimplifyShortImmForm(OutMI, X86::SBB8i8); break;
case X86::SBB16ri: SimplifyShortImmForm(OutMI, X86::SBB16i16); break;
case X86::SBB32ri: SimplifyShortImmForm(OutMI, X86::SBB32i32); break;
case X86::SBB64ri32: SimplifyShortImmForm(OutMI, X86::SBB64i32); break;
case X86::SUB8ri: SimplifyShortImmForm(OutMI, X86::SUB8i8); break;
case X86::SUB16ri: SimplifyShortImmForm(OutMI, X86::SUB16i16); break;
case X86::SUB32ri: SimplifyShortImmForm(OutMI, X86::SUB32i32); break;
case X86::SUB64ri32: SimplifyShortImmForm(OutMI, X86::SUB64i32); break;
case X86::TEST8ri: SimplifyShortImmForm(OutMI, X86::TEST8i8); break;
case X86::TEST16ri: SimplifyShortImmForm(OutMI, X86::TEST16i16); break;
case X86::TEST32ri: SimplifyShortImmForm(OutMI, X86::TEST32i32); break;
case X86::TEST64ri32: SimplifyShortImmForm(OutMI, X86::TEST64i32); break;
case X86::XOR8ri: SimplifyShortImmForm(OutMI, X86::XOR8i8); break;
case X86::XOR16ri: SimplifyShortImmForm(OutMI, X86::XOR16i16); break;
case X86::XOR32ri: SimplifyShortImmForm(OutMI, X86::XOR32i32); break;
case X86::XOR64ri32: SimplifyShortImmForm(OutMI, X86::XOR64i32); break;
} }
} }

26
test/CodeGen/X86/mcinst-lowering.ll Normal file
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@ -0,0 +1,26 @@
; RUN: llc --show-mc-encoding < %s | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-darwin10.0.0"
define i32 @f0(i32* nocapture %x) nounwind readonly ssp {
entry:
%tmp1 = load i32* %x ; <i32> [#uses=2]
%tobool = icmp eq i32 %tmp1, 0 ; <i1> [#uses=1]
br i1 %tobool, label %if.end, label %return
if.end: ; preds = %entry
; Check that we lower to the short form of cmpl, which has a fixed %eax
; register.
;
; CHECK: cmpl $16777216, %eax
; CHECK: # encoding: [0x3d,0x00,0x00,0x00,0x01]
%cmp = icmp eq i32 %tmp1, 16777216 ; <i1> [#uses=1]
%conv = zext i1 %cmp to i32 ; <i32> [#uses=1]
ret i32 %conv
return: ; preds = %entry
ret i32 0
}