Files
clang-p2996/llvm/lib/Target/BPF/InstPrinter/BPFInstPrinter.cpp
Yonghong Song 25bf825961 bpf: add support for objdump -print-imm-hex
Add support for 'objdump -print-imm-hex' for imm64, operand imm
and branch target. If user programs encode immediate values
as hex numbers, such an option will make it easy to correlate
asm insns with source code. This option also makes it easy
to correlate imm values with insn encoding.

There is one changed behavior in this patch. In old way, we
print the 64bit imm as u64:
  O << (uint64_t)Op.getImm();
and the new way is:
  O << formatImm(Op.getImm());

The formatImm is defined in llvm/MC/MCInstPrinter.h as
  format_object<int64_t> formatImm(int64_t Value)

So the new way to print 64bit imm is i64 type.
If a 64bit value has the highest bit set, the old way
will print the value as a positive value and the
new way will print as a negative value. The new way
is consistent with x86_64.
For the code (see the test program):
 ...
 if (a == 0xABCDABCDabcdabcdULL)
 ...
x86_64 objdump, with and without -print-imm-hex, looks like:
 48 b8 cd ab cd ab cd ab cd ab   movabsq $-6067004223159161907, %rax
 48 b8 cd ab cd ab cd ab cd ab   movabsq $-0x5432543254325433, %rax

Signed-off-by: Yonghong Song <yhs@fb.com>
llvm-svn: 321215
2017-12-20 19:39:58 +00:00

110 lines
3.2 KiB
C++

//===-- BPFInstPrinter.cpp - Convert BPF MCInst to asm 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 BPF MCInst to a .s file.
//
//===----------------------------------------------------------------------===//
#include "BPFInstPrinter.h"
#include "BPF.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
using namespace llvm;
#define DEBUG_TYPE "asm-printer"
// Include the auto-generated portion of the assembly writer.
#include "BPFGenAsmWriter.inc"
void BPFInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
StringRef Annot, const MCSubtargetInfo &STI) {
printInstruction(MI, O);
printAnnotation(O, Annot);
}
static void printExpr(const MCExpr *Expr, raw_ostream &O) {
#ifndef NDEBUG
const MCSymbolRefExpr *SRE;
if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(Expr))
SRE = dyn_cast<MCSymbolRefExpr>(BE->getLHS());
else
SRE = dyn_cast<MCSymbolRefExpr>(Expr);
assert(SRE && "Unexpected MCExpr type.");
MCSymbolRefExpr::VariantKind Kind = SRE->getKind();
assert(Kind == MCSymbolRefExpr::VK_None);
#endif
O << *Expr;
}
void BPFInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O, const char *Modifier) {
assert((Modifier == 0 || Modifier[0] == 0) && "No modifiers supported");
const MCOperand &Op = MI->getOperand(OpNo);
if (Op.isReg()) {
O << getRegisterName(Op.getReg());
} else if (Op.isImm()) {
O << formatImm((int32_t)Op.getImm());
} else {
assert(Op.isExpr() && "Expected an expression");
printExpr(Op.getExpr(), O);
}
}
void BPFInstPrinter::printMemOperand(const MCInst *MI, int OpNo, raw_ostream &O,
const char *Modifier) {
const MCOperand &RegOp = MI->getOperand(OpNo);
const MCOperand &OffsetOp = MI->getOperand(OpNo + 1);
// register
assert(RegOp.isReg() && "Register operand not a register");
O << getRegisterName(RegOp.getReg());
// offset
if (OffsetOp.isImm()) {
auto Imm = OffsetOp.getImm();
if (Imm >= 0)
O << " + " << formatImm(Imm);
else
O << " - " << formatImm(-Imm);
} else {
assert(0 && "Expected an immediate");
}
}
void BPFInstPrinter::printImm64Operand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
const MCOperand &Op = MI->getOperand(OpNo);
if (Op.isImm())
O << formatImm(Op.getImm());
else if (Op.isExpr())
printExpr(Op.getExpr(), O);
else
O << Op;
}
void BPFInstPrinter::printBrTargetOperand(const MCInst *MI, unsigned OpNo,
raw_ostream &O) {
const MCOperand &Op = MI->getOperand(OpNo);
if (Op.isImm()) {
int16_t Imm = Op.getImm();
O << ((Imm >= 0) ? "+" : "") << formatImm(Imm);
} else if (Op.isExpr()) {
printExpr(Op.getExpr(), O);
} else {
O << Op;
}
}