Fix issues with the ARM bl and blx thumb instructions and the J1 and J2 bits
for the assembler and disassembler. Which were not being set/read correctly
for offsets greater than 22 bits in some cases.
Changes to lib/Target/ARM/ARMAsmBackend.cpp from Gideon Myles!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156118 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index fe553c2..ce6785a 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -427,11 +427,11 @@
"bl${p}\t$func",
[(ARMtcall tglobaladdr:$func)]>,
Requires<[IsThumb]> {
- bits<22> func;
- let Inst{26} = func{21};
+ bits<24> func;
+ let Inst{26} = func{23};
let Inst{25-16} = func{20-11};
- let Inst{13} = 1;
- let Inst{11} = 1;
+ let Inst{13} = func{22};
+ let Inst{11} = func{21};
let Inst{10-0} = func{10-0};
}
@@ -441,10 +441,11 @@
"blx${p}\t$func",
[(ARMcall tglobaladdr:$func)]>,
Requires<[IsThumb, HasV5T]> {
- bits<21> func;
+ bits<24> func;
+ let Inst{26} = func{23};
let Inst{25-16} = func{20-11};
- let Inst{13} = 1;
- let Inst{11} = 1;
+ let Inst{13} = func{22};
+ let Inst{11} = func{21};
let Inst{10-1} = func{10-1};
let Inst{0} = 0; // func{0} is assumed zero
}
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 28ea0d2..80b2b23 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -3339,10 +3339,25 @@
static DecodeStatus DecodeThumbBLXOffset(MCInst &Inst, unsigned Val,
uint64_t Address, const void *Decoder) {
+ // Val is passed in as S:J1:J2:imm10H:imm10L:’0’
+ // Note only one trailing zero not two. Also the J1 and J2 values are from
+ // the encoded instruction. So here change to I1 and I2 values via:
+ // I1 = NOT(J1 EOR S);
+ // I2 = NOT(J2 EOR S);
+ // and build the imm32 with two trailing zeros as documented:
+ // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:’00’, 32);
+ unsigned S = (Val >> 23) & 1;
+ unsigned J1 = (Val >> 22) & 1;
+ unsigned J2 = (Val >> 21) & 1;
+ unsigned I1 = !(J1 ^ S);
+ unsigned I2 = !(J2 ^ S);
+ unsigned tmp = (Val & ~0x600000) | (I1 << 22) | (I2 << 21);
+ int imm32 = SignExtend32<25>(tmp << 1);
+
if (!tryAddingSymbolicOperand(Address,
- (Address & ~2u) + SignExtend32<22>(Val << 1) + 4,
+ (Address & ~2u) + imm32 + 4,
true, 4, Inst, Decoder))
- Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
+ Inst.addOperand(MCOperand::CreateImm(imm32));
return MCDisassembler::Success;
}
@@ -3456,9 +3471,24 @@
static DecodeStatus DecodeThumbBLTargetOperand(MCInst &Inst, unsigned Val,
uint64_t Address, const void *Decoder){
- if (!tryAddingSymbolicOperand(Address, Address + SignExtend32<22>(Val<<1) + 4,
+ // Val is passed in as S:J1:J2:imm10:imm11
+ // Note no trailing zero after imm11. Also the J1 and J2 values are from
+ // the encoded instruction. So here change to I1 and I2 values via:
+ // I1 = NOT(J1 EOR S);
+ // I2 = NOT(J2 EOR S);
+ // and build the imm32 with one trailing zero as documented:
+ // imm32 = SignExtend(S:I1:I2:imm10:imm11:’0’, 32);
+ unsigned S = (Val >> 23) & 1;
+ unsigned J1 = (Val >> 22) & 1;
+ unsigned J2 = (Val >> 21) & 1;
+ unsigned I1 = !(J1 ^ S);
+ unsigned I2 = !(J2 ^ S);
+ unsigned tmp = (Val & ~0x600000) | (I1 << 22) | (I2 << 21);
+ int imm32 = SignExtend32<25>(tmp << 1);
+
+ if (!tryAddingSymbolicOperand(Address, Address + imm32 + 4,
true, 4, Inst, Decoder))
- Inst.addOperand(MCOperand::CreateImm(SignExtend32<22>(Val << 1)));
+ Inst.addOperand(MCOperand::CreateImm(imm32));
return MCDisassembler::Success;
}
diff --git a/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 9550677..ac6ce64 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -394,39 +394,65 @@
return swapped;
}
case ARM::fixup_arm_thumb_bl: {
- // The value doesn't encode the low bit (always zero) and is offset by
- // four. The value is encoded into disjoint bit positions in the destination
- // opcode. x = unchanged, I = immediate value bit, S = sign extension bit
- //
- // BL: xxxxxSIIIIIIIIII xxxxxIIIIIIIIIII
- //
- // Note that the halfwords are stored high first, low second; so we need
- // to transpose the fixup value here to map properly.
- unsigned isNeg = (int64_t(Value - 4) < 0) ? 1 : 0;
- uint32_t Binary = 0;
- Value = 0x3fffff & ((Value - 4) >> 1);
- Binary = (Value & 0x7ff) << 16; // Low imm11 value.
- Binary |= (Value & 0x1ffc00) >> 11; // High imm10 value.
- Binary |= isNeg << 10; // Sign bit.
- return Binary;
+ // The value doesn't encode the low bit (always zero) and is offset by
+ // four. The 32-bit immediate value is encoded as
+ // imm32 = SignExtend(S:I1:I2:imm10:imm11:0)
+ // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
+ // The value is encoded into disjoint bit positions in the destination
+ // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
+ // J = either J1 or J2 bit
+ //
+ // BL: xxxxxSIIIIIIIIII xxJxJIIIIIIIIIII
+ //
+ // Note that the halfwords are stored high first, low second; so we need
+ // to transpose the fixup value here to map properly.
+ uint32_t offset = (Value - 4) >> 1;
+ uint32_t signBit = (offset & 0x800000) >> 23;
+ uint32_t I1Bit = (offset & 0x400000) >> 22;
+ uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
+ uint32_t I2Bit = (offset & 0x200000) >> 21;
+ uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
+ uint32_t imm10Bits = (offset & 0x1FF800) >> 11;
+ uint32_t imm11Bits = (offset & 0x000007FF);
+
+ uint32_t Binary = 0;
+ uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10Bits);
+ uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
+ (uint16_t)imm11Bits);
+ Binary |= secondHalf << 16;
+ Binary |= firstHalf;
+ return Binary;
+
}
case ARM::fixup_arm_thumb_blx: {
- // The value doesn't encode the low two bits (always zero) and is offset by
- // four (see fixup_arm_thumb_cp). The value is encoded into disjoint bit
- // positions in the destination opcode. x = unchanged, I = immediate value
- // bit, S = sign extension bit, 0 = zero.
- //
- // BLX: xxxxxSIIIIIIIIII xxxxxIIIIIIIIII0
- //
- // Note that the halfwords are stored high first, low second; so we need
- // to transpose the fixup value here to map properly.
- unsigned isNeg = (int64_t(Value-4) < 0) ? 1 : 0;
- uint32_t Binary = 0;
- Value = 0xfffff & ((Value - 2) >> 2);
- Binary = (Value & 0x3ff) << 17; // Low imm10L value.
- Binary |= (Value & 0xffc00) >> 10; // High imm10H value.
- Binary |= isNeg << 10; // Sign bit.
- return Binary;
+ // The value doesn't encode the low two bits (always zero) and is offset by
+ // four (see fixup_arm_thumb_cp). The 32-bit immediate value is encoded as
+ // imm32 = SignExtend(S:I1:I2:imm10H:imm10L:00)
+ // where I1 = NOT(J1 ^ S) and I2 = NOT(J2 ^ S).
+ // The value is encoded into disjoint bit positions in the destination
+ // opcode. x = unchanged, I = immediate value bit, S = sign extension bit,
+ // J = either J1 or J2 bit, 0 = zero.
+ //
+ // BLX: xxxxxSIIIIIIIIII xxJxJIIIIIIIIII0
+ //
+ // Note that the halfwords are stored high first, low second; so we need
+ // to transpose the fixup value here to map properly.
+ uint32_t offset = (Value - 2) >> 2;
+ uint32_t signBit = (offset & 0x400000) >> 22;
+ uint32_t I1Bit = (offset & 0x200000) >> 21;
+ uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;
+ uint32_t I2Bit = (offset & 0x100000) >> 20;
+ uint32_t J2Bit = (I2Bit ^ 0x1) ^ signBit;
+ uint32_t imm10HBits = (offset & 0xFFC00) >> 10;
+ uint32_t imm10LBits = (offset & 0x3FF);
+
+ uint32_t Binary = 0;
+ uint32_t firstHalf = (((uint16_t)signBit << 10) | (uint16_t)imm10HBits);
+ uint32_t secondHalf = (((uint16_t)J1Bit << 13) | ((uint16_t)J2Bit << 11) |
+ ((uint16_t)imm10LBits) << 1);
+ Binary |= secondHalf << 16;
+ Binary |= firstHalf;
+ return Binary;
}
case ARM::fixup_arm_thumb_cp:
// Offset by 4, and don't encode the low two bits. Two bytes of that