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clang-p2996/llvm/lib/Target/PowerPC/InstPrinter/PPCInstPrinter.cpp
Ulrich Weigand 1931b01a64 [PowerPC] Remove incorrect use of COPY_TO_REGCLASS in fast isel 
The fast isel pass currently emits a COPY_TO_REGCLASS node to convert
from a F4RC to a F8RC register class during conversion of a
floating-point number to integer. There is actually no support in the
common code instruction printers to emit COPY_TO_REGCLASS nodes, so the
PowerPC back-end has special code there to simply ignore
COPY_TO_REGCLASS.

This is correct *if and only if* the source and destination registers of
COPY_TO_REGCLASS are the same (except for the different register class).
But nothing guarantees this to be the case, and if the register
allocator does end up allocating source and destination to different
registers after all, the back-end simply generates incorrect code. I've
included a test case that shows such incorrect code generation.

However, it seems that COPY_TO_REGCLASS is actually not intended to be
used at the MI layer at all. It is used during SelectionDAG, but always
lowered to a plain COPY before emitting MI. Other back-end's fast isel
passes never emit COPY_TO_REGCLASS at all. I suspect it is simply wrong
for the PowerPC back-end to emit it here.

This patch changes the PowerPC back-end to directly emit COPY instead of
COPY_TO_REGCLASS and removes the special handling in the instruction
printers.

Differential Revision: http://reviews.llvm.org/D18605

llvm-svn: 265020
2016-03-31 14:44:50 +00:00

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//===-- PPCInstPrinter.cpp - Convert PPC MCInst to assembly syntax --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class prints an PPC MCInst to a .s file.
//
//===----------------------------------------------------------------------===//
#include "PPCInstPrinter.h"
#include "MCTargetDesc/PPCMCTargetDesc.h"
#include "MCTargetDesc/PPCPredicates.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetOpcodes.h"
using namespace llvm;
#define DEBUG_TYPE "asm-printer"
// FIXME: Once the integrated assembler supports full register names, tie this
// to the verbose-asm setting.
static cl::opt<bool>
FullRegNames("ppc-asm-full-reg-names", cl::Hidden, cl::init(false),
cl::desc("Use full register names when printing assembly"));
#define PRINT_ALIAS_INSTR
#include "PPCGenAsmWriter.inc"
void PPCInstPrinter::printRegName(raw_ostream &OS, unsigned RegNo) const {
const char *RegName = getRegisterName(RegNo);
if (RegName[0] == 'q' /* QPX */) {
// The system toolchain on the BG/Q does not understand QPX register names
// in .cfi_* directives, so print the name of the floating-point
// subregister instead.
std::string RN(RegName);
RN[0] = 'f';
OS << RN;
return;
}
OS << RegName;
}
void PPCInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
StringRef Annot, const MCSubtargetInfo &STI) {
// Check for slwi/srwi mnemonics.
if (MI->getOpcode() == PPC::RLWINM) {
unsigned char SH = MI->getOperand(2).getImm();
unsigned char MB = MI->getOperand(3).getImm();
unsigned char ME = MI->getOperand(4).getImm();
bool useSubstituteMnemonic = false;
if (SH <= 31 && MB == 0 && ME == (31-SH)) {
O << "\tslwi "; useSubstituteMnemonic = true;
}
if (SH <= 31 && MB == (32-SH) && ME == 31) {
O << "\tsrwi "; useSubstituteMnemonic = true;
SH = 32-SH;
}
if (useSubstituteMnemonic) {
printOperand(MI, 0, O);
O << ", ";
printOperand(MI, 1, O);
O << ", " << (unsigned int)SH;
printAnnotation(O, Annot);
return;
}
}
if ((MI->getOpcode() == PPC::OR || MI->getOpcode() == PPC::OR8) &&
MI->getOperand(1).getReg() == MI->getOperand(2).getReg()) {
O << "\tmr ";
printOperand(MI, 0, O);
O << ", ";
printOperand(MI, 1, O);
printAnnotation(O, Annot);
return;
}
if (MI->getOpcode() == PPC::RLDICR) {
unsigned char SH = MI->getOperand(2).getImm();
unsigned char ME = MI->getOperand(3).getImm();
// rldicr RA, RS, SH, 63-SH == sldi RA, RS, SH
if (63-SH == ME) {
O << "\tsldi ";
printOperand(MI, 0, O);
O << ", ";
printOperand(MI, 1, O);
O << ", " << (unsigned int)SH;
printAnnotation(O, Annot);
return;
}
}
// dcbt[st] is printed manually here because:
// 1. The assembly syntax is different between embedded and server targets
// 2. We must print the short mnemonics for TH == 0 because the
// embedded/server syntax default will not be stable across assemblers
// The syntax for dcbt is:
// dcbt ra, rb, th [server]
// dcbt th, ra, rb [embedded]
// where th can be omitted when it is 0. dcbtst is the same.
if (MI->getOpcode() == PPC::DCBT || MI->getOpcode() == PPC::DCBTST) {
unsigned char TH = MI->getOperand(0).getImm();
O << "\tdcbt";
if (MI->getOpcode() == PPC::DCBTST)
O << "st";
if (TH == 16)
O << "t";
O << " ";
bool IsBookE = STI.getFeatureBits()[PPC::FeatureBookE];
if (IsBookE && TH != 0 && TH != 16)
O << (unsigned int) TH << ", ";
printOperand(MI, 1, O);
O << ", ";
printOperand(MI, 2, O);
if (!IsBookE && TH != 0 && TH != 16)
O << ", " << (unsigned int) TH;
printAnnotation(O, Annot);
return;
}
if (!printAliasInstr(MI, O))
printInstruction(MI, O);
printAnnotation(O, Annot);
}
void PPCInstPrinter::printPredicateOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O,
const char *Modifier) {
unsigned Code = MI->getOperand(OpNo).getImm();
if (StringRef(Modifier) == "cc") {
switch ((PPC::Predicate)Code) {
case PPC::PRED_LT_MINUS:
case PPC::PRED_LT_PLUS:
case PPC::PRED_LT:
O << "lt";
return;
case PPC::PRED_LE_MINUS:
case PPC::PRED_LE_PLUS:
case PPC::PRED_LE:
O << "le";
return;
case PPC::PRED_EQ_MINUS:
case PPC::PRED_EQ_PLUS:
case PPC::PRED_EQ:
O << "eq";
return;
case PPC::PRED_GE_MINUS:
case PPC::PRED_GE_PLUS:
case PPC::PRED_GE:
O << "ge";
return;
case PPC::PRED_GT_MINUS:
case PPC::PRED_GT_PLUS:
case PPC::PRED_GT:
O << "gt";
return;
case PPC::PRED_NE_MINUS:
case PPC::PRED_NE_PLUS:
case PPC::PRED_NE:
O << "ne";
return;
case PPC::PRED_UN_MINUS:
case PPC::PRED_UN_PLUS:
case PPC::PRED_UN:
O << "un";
return;
case PPC::PRED_NU_MINUS:
case PPC::PRED_NU_PLUS:
case PPC::PRED_NU:
O << "nu";
return;
case PPC::PRED_BIT_SET:
case PPC::PRED_BIT_UNSET:
llvm_unreachable("Invalid use of bit predicate code");
}
llvm_unreachable("Invalid predicate code");
}
if (StringRef(Modifier) == "pm") {
switch ((PPC::Predicate)Code) {
case PPC::PRED_LT:
case PPC::PRED_LE:
case PPC::PRED_EQ:
case PPC::PRED_GE:
case PPC::PRED_GT:
case PPC::PRED_NE:
case PPC::PRED_UN:
case PPC::PRED_NU:
return;
case PPC::PRED_LT_MINUS:
case PPC::PRED_LE_MINUS:
case PPC::PRED_EQ_MINUS:
case PPC::PRED_GE_MINUS:
case PPC::PRED_GT_MINUS:
case PPC::PRED_NE_MINUS:
case PPC::PRED_UN_MINUS:
case PPC::PRED_NU_MINUS:
O << "-";
return;
case PPC::PRED_LT_PLUS:
case PPC::PRED_LE_PLUS:
case PPC::PRED_EQ_PLUS:
case PPC::PRED_GE_PLUS:
case PPC::PRED_GT_PLUS:
case PPC::PRED_NE_PLUS:
case PPC::PRED_UN_PLUS:
case PPC::PRED_NU_PLUS:
O << "+";
return;
case PPC::PRED_BIT_SET:
case PPC::PRED_BIT_UNSET:
llvm_unreachable("Invalid use of bit predicate code");
}
llvm_unreachable("Invalid predicate code");
}
assert(StringRef(Modifier) == "reg" &&
"Need to specify 'cc', 'pm' or 'reg' as predicate op modifier!");
printOperand(MI, OpNo+1, O);
}
void PPCInstPrinter::printU1ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 1 && "Invalid u1imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU2ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 3 && "Invalid u2imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU3ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 8 && "Invalid u3imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU4ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 15 && "Invalid u4imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printS5ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
int Value = MI->getOperand(OpNo).getImm();
Value = SignExtend32<5>(Value);
O << (int)Value;
}
void PPCInstPrinter::printU5ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 31 && "Invalid u5imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU6ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 63 && "Invalid u6imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU7ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 127 && "Invalid u7imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU8ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned int Value = MI->getOperand(OpNo).getImm();
assert(Value <= 255 && "Invalid u8imm argument!");
O << (unsigned int)Value;
}
void PPCInstPrinter::printU10ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned short Value = MI->getOperand(OpNo).getImm();
assert(Value <= 1023 && "Invalid u10imm argument!");
O << (unsigned short)Value;
}
void PPCInstPrinter::printU12ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned short Value = MI->getOperand(OpNo).getImm();
assert(Value <= 4095 && "Invalid u12imm argument!");
O << (unsigned short)Value;
}
void PPCInstPrinter::printS16ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (MI->getOperand(OpNo).isImm())
O << (short)MI->getOperand(OpNo).getImm();
else
printOperand(MI, OpNo, O);
}
void PPCInstPrinter::printU16ImmOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (MI->getOperand(OpNo).isImm())
O << (unsigned short)MI->getOperand(OpNo).getImm();
else
printOperand(MI, OpNo, O);
}
void PPCInstPrinter::printBranchOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (!MI->getOperand(OpNo).isImm())
return printOperand(MI, OpNo, O);
// Branches can take an immediate operand. This is used by the branch
// selection pass to print .+8, an eight byte displacement from the PC.
O << ".+";
printAbsBranchOperand(MI, OpNo, O);
}
void PPCInstPrinter::printAbsBranchOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
if (!MI->getOperand(OpNo).isImm())
return printOperand(MI, OpNo, O);
O << SignExtend32<32>((unsigned)MI->getOperand(OpNo).getImm() << 2);
}
void PPCInstPrinter::printcrbitm(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
unsigned CCReg = MI->getOperand(OpNo).getReg();
unsigned RegNo;
switch (CCReg) {
default: llvm_unreachable("Unknown CR register");
case PPC::CR0: RegNo = 0; break;
case PPC::CR1: RegNo = 1; break;
case PPC::CR2: RegNo = 2; break;
case PPC::CR3: RegNo = 3; break;
case PPC::CR4: RegNo = 4; break;
case PPC::CR5: RegNo = 5; break;
case PPC::CR6: RegNo = 6; break;
case PPC::CR7: RegNo = 7; break;
}
O << (0x80 >> RegNo);
}
void PPCInstPrinter::printMemRegImm(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
printS16ImmOperand(MI, OpNo, O);
O << '(';
if (MI->getOperand(OpNo+1).getReg() == PPC::R0)
O << "0";
else
printOperand(MI, OpNo+1, O);
O << ')';
}
void PPCInstPrinter::printMemRegReg(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
// When used as the base register, r0 reads constant zero rather than
// the value contained in the register. For this reason, the darwin
// assembler requires that we print r0 as 0 (no r) when used as the base.
if (MI->getOperand(OpNo).getReg() == PPC::R0)
O << "0";
else
printOperand(MI, OpNo, O);
O << ", ";
printOperand(MI, OpNo+1, O);
}
void PPCInstPrinter::printTLSCall(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
// On PPC64, VariantKind is VK_None, but on PPC32, it's VK_PLT, and it must
// come at the _end_ of the expression.
const MCOperand &Op = MI->getOperand(OpNo);
const MCSymbolRefExpr &refExp = cast<MCSymbolRefExpr>(*Op.getExpr());
O << refExp.getSymbol().getName();
O << '(';
printOperand(MI, OpNo+1, O);
O << ')';
if (refExp.getKind() != MCSymbolRefExpr::VK_None)
O << '@' << MCSymbolRefExpr::getVariantKindName(refExp.getKind());
}
/// stripRegisterPrefix - This method strips the character prefix from a
/// register name so that only the number is left. Used by for linux asm.
static const char *stripRegisterPrefix(const char *RegName) {
if (FullRegNames)
return RegName;
switch (RegName[0]) {
case 'r':
case 'f':
case 'q': // for QPX
case 'v':
if (RegName[1] == 's')
return RegName + 2;
return RegName + 1;
case 'c': if (RegName[1] == 'r') return RegName + 2;
}
return RegName;
}
void PPCInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
const MCOperand &Op = MI->getOperand(OpNo);
if (Op.isReg()) {
const char *RegName = getRegisterName(Op.getReg());
// The linux and AIX assembler does not take register prefixes.
if (!isDarwinSyntax())
RegName = stripRegisterPrefix(RegName);
O << RegName;
return;
}
if (Op.isImm()) {
O << Op.getImm();
return;
}
assert(Op.isExpr() && "unknown operand kind in printOperand");
Op.getExpr()->print(O, &MAI);
}
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