diff options
| -rw-r--r-- | llvm/lib/MC/MCAssembler.cpp | 49 |
1 files changed, 47 insertions, 2 deletions
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp index 2c698e76f92..96227dbee50 100644 --- a/llvm/lib/MC/MCAssembler.cpp +++ b/llvm/lib/MC/MCAssembler.cpp @@ -1066,9 +1066,54 @@ void MCAssembler::LayoutSection(MCSectionData &SD) { /// /// FIXME this is X86 32-bit specific and should move to a better place. static uint64_t WriteNopData(uint64_t Count, MachObjectWriter &MOW) { - // FIXME for now just use the 0x90 nop opcode byte. + static const uint8_t Nops[16][16] = { + // nop + {0x90}, + // xchg %ax,%ax + {0x66, 0x90}, + // nopl (%[re]ax) + {0x0f, 0x1f, 0x00}, + // nopl 0(%[re]ax) + {0x0f, 0x1f, 0x40, 0x00}, + // nopl 0(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopl 0L(%[re]ax) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + // nopw 0L(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + // nopw %cs:0L(%[re]ax,%[re]ax,1) + {0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, + // nopl 0(%[re]ax,%[re]ax,1) + // nopw 0(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + // nopw 0(%[re]ax,%[re]ax,1) + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00}, + // nopw 0(%[re]ax,%[re]ax,1) + // nopl 0L(%[re]ax) */ + {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00, + 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax) + // nopl 0L(%[re]ax) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00, + 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00}, + // nopl 0L(%[re]ax) + // nopl 0L(%[re]ax,%[re]ax,1) + {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00, + 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00} + }; + + if (Count > 15) + return 0; + for (uint64_t i = 0; i < Count; i++) - MOW.Write8 (uint8_t(0x90)); + MOW.Write8 (uint8_t(Nops[Count - 1][i])); return Count; } |
