diff options
Diffstat (limited to 'llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp')
| -rw-r--r-- | llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp | 75 |
1 files changed, 55 insertions, 20 deletions
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp index 1fe2dbe7866..75d33212ac9 100644 --- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp +++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp @@ -181,9 +181,8 @@ bool ARMAsmBackend::mayNeedRelaxation(const MCInst &Inst) const { return false; } -bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, - const MCRelaxableFragment *DF, - const MCAsmLayout &Layout) const { +const char *ARMAsmBackend::reasonForFixupRelaxation(const MCFixup &Fixup, + uint64_t Value) const { switch ((unsigned)Fixup.getKind()) { case ARM::fixup_arm_thumb_br: { // Relaxing tB to t2B. tB has a signed 12-bit displacement with the @@ -193,7 +192,9 @@ bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, // // Relax if the value is too big for a (signed) i8. int64_t Offset = int64_t(Value) - 4; - return Offset > 2046 || Offset < -2048; + if (Offset > 2046 || Offset < -2048) + return "out of range pc-relative fixup value"; + break; } case ARM::fixup_arm_thumb_bcc: { // Relaxing tBcc to t2Bcc. tBcc has a signed 9-bit displacement with the @@ -203,23 +204,40 @@ bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, // // Relax if the value is too big for a (signed) i8. int64_t Offset = int64_t(Value) - 4; - return Offset > 254 || Offset < -256; + if (Offset > 254 || Offset < -256) + return "out of range pc-relative fixup value"; + break; } case ARM::fixup_thumb_adr_pcrel_10: case ARM::fixup_arm_thumb_cp: { // If the immediate is negative, greater than 1020, or not a multiple // of four, the wide version of the instruction must be used. int64_t Offset = int64_t(Value) - 4; - return Offset > 1020 || Offset < 0 || Offset & 3; + if (Offset & 3) + return "misaligned pc-relative fixup value"; + else if (Offset > 1020 || Offset < 0) + return "out of range pc-relative fixup value"; + break; } - case ARM::fixup_arm_thumb_cb: + case ARM::fixup_arm_thumb_cb: { // If we have a Thumb CBZ or CBNZ instruction and its target is the next // instruction it is is actually out of range for the instruction. // It will be changed to a NOP. int64_t Offset = (Value & ~1); - return Offset == 2; + if (Offset == 2) + return "will be converted to nop"; + break; } - llvm_unreachable("Unexpected fixup kind in fixupNeedsRelaxation()!"); + default: + llvm_unreachable("Unexpected fixup kind in reasonForFixupRelaxation()!"); + } + return nullptr; +} + +bool ARMAsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value, + const MCRelaxableFragment *DF, + const MCAsmLayout &Layout) const { + return reasonForFixupRelaxation(Fixup, Value); } void ARMAsmBackend::relaxInstruction(const MCInst &Inst, MCInst &Res) const { @@ -318,9 +336,10 @@ static uint32_t joinHalfWords(uint32_t FirstHalf, uint32_t SecondHalf, return Value; } -static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value, - bool IsPCRel, MCContext *Ctx, - bool IsLittleEndian) { +unsigned ARMAsmBackend::adjustFixupValue(const MCFixup &Fixup, uint64_t Value, + bool IsPCRel, MCContext *Ctx, + bool IsLittleEndian, + bool IsResolved) const { unsigned Kind = Fixup.getKind(); switch (Kind) { default: @@ -384,8 +403,6 @@ static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value, return Value; } - case ARM::fixup_thumb_adr_pcrel_10: - return ((Value - 4) >> 2) & 0xff; case ARM::fixup_arm_adr_pcrel_12: { // ARM PC-relative values are offset by 8. Value -= 8; @@ -518,21 +535,38 @@ static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value, ((uint16_t)imm10LBits) << 1); return joinHalfWords(FirstHalf, SecondHalf, IsLittleEndian); } + case ARM::fixup_thumb_adr_pcrel_10: case ARM::fixup_arm_thumb_cp: - // Offset by 4, and don't encode the low two bits. Two bytes of that - // 'off by 4' is implicitly handled by the half-word ordering of the - // Thumb encoding, so we only need to adjust by 2 here. - return ((Value - 2) >> 2) & 0xff; + // On CPUs supporting Thumb2, this will be relaxed to an ldr.w, otherwise we + // could have an error on our hands. + if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2] && IsResolved) { + const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value); + if (FixupDiagnostic) + Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic); + } + // Offset by 4, and don't encode the low two bits. + return ((Value - 4) >> 2) & 0xff; case ARM::fixup_arm_thumb_cb: { // Offset by 4 and don't encode the lower bit, which is always 0. + // FIXME: diagnose if no Thumb2 uint32_t Binary = (Value - 4) >> 1; return ((Binary & 0x20) << 4) | ((Binary & 0x1f) << 3); } case ARM::fixup_arm_thumb_br: // Offset by 4 and don't encode the lower bit, which is always 0. + if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2]) { + const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value); + if (FixupDiagnostic) + Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic); + } return ((Value - 4) >> 1) & 0x7ff; case ARM::fixup_arm_thumb_bcc: // Offset by 4 and don't encode the lower bit, which is always 0. + if (Ctx && !STI->getFeatureBits()[ARM::FeatureThumb2]) { + const char *FixupDiagnostic = reasonForFixupRelaxation(Fixup, Value); + if (FixupDiagnostic) + Ctx->reportFatalError(Fixup.getLoc(), FixupDiagnostic); + } return ((Value - 4) >> 1) & 0xff; case ARM::fixup_arm_pcrel_10_unscaled: { Value = Value - 8; // ARM fixups offset by an additional word and don't @@ -617,7 +651,7 @@ void ARMAsmBackend::processFixupValue(const MCAssembler &Asm, // the instruction. This allows adjustFixupValue() to issue a diagnostic // if the value aren't invalid. (void)adjustFixupValue(Fixup, Value, false, &Asm.getContext(), - IsLittleEndian); + IsLittleEndian, IsResolved); } /// getFixupKindNumBytes - The number of bytes the fixup may change. @@ -720,7 +754,8 @@ void ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize, uint64_t Value, bool IsPCRel) const { unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind()); - Value = adjustFixupValue(Fixup, Value, IsPCRel, nullptr, IsLittleEndian); + Value = + adjustFixupValue(Fixup, Value, IsPCRel, nullptr, IsLittleEndian, true); if (!Value) return; // Doesn't change encoding. |
