6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-29 10:25:12 +00:00
Code Issues Projects Releases Wiki Activity

In Thumb2, direct branches can be encoded as either a "short" conditional branch with a null predicate, or

Browse Source 
as a "long" direct branch.  While the mnemonics are the same, they encode the branch offset differently, and
the Darwin assembler appears to prefer the "long" form for direct branches.  Thus, in the name of bitwise
equivalence, provide encoding and fixup support for it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121710 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2010-12-13 19:31:11 +00:00
parent 56a2535474
commit c266600bec
8 changed files with 73 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
lib/Target/ARM/ARMAsmBackend.cpp
View File

@@ -140,11 +140,32 @@ static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
// These values don't encode the low two bits since they're always zero.
// Offset by 8 just as above.
return 0xffffff & ((Value - 8) >> 2);
case ARM::fixup_t2_branch: {
case ARM::fixup_t2_uncondbranch: {
Value = Value - 4;
Value >>= 1; // Low bit is not encoded.
uint32_t out = 0;
bool I = Value & 0x800000;
bool J1 = Value & 0x400000;
bool J2 = Value & 0x200000;
J1 ^= I;
J2 ^= I;
out |= I << 26; // S bit
out |= !J1 << 13; // J1 bit
out |= !J2 << 11; // J2 bit
out |= (Value & 0x1FF800) << 5; // imm6 field
out |= (Value & 0x0007FF); // imm11 field
uint64_t swapped = (out & 0xFFFF0000) >> 16;
swapped |= (out & 0x0000FFFF) << 16;
return swapped;
}
case ARM::fixup_t2_condbranch: {
Value = Value - 4;
Value >>= 1; // Low bit is not encoded.
uint64_t out = 0;
out |= (Value & 0x80000) << 7; // S bit
out |= (Value & 0x40000) >> 7; // J2 bit
out |= (Value & 0x20000) >> 4; // J1 bit
@@ -332,7 +353,8 @@ static unsigned getFixupKindNumBytes(unsigned Kind) {
case FK_Data_4:
case ARM::fixup_t2_ldst_pcrel_12:
case ARM::fixup_t2_branch:
case ARM::fixup_t2_condbranch:
case ARM::fixup_t2_uncondbranch:
case ARM::fixup_t2_pcrel_10:
case ARM::fixup_arm_thumb_bl:
case ARM::fixup_arm_thumb_blx: