text section.
Assume the following bit of annotated assembly:
.section .data.rel.ro,"aw",%progbits
.align 2
.LAlpha:
.long startval(GOTOFF)
.text
.align 2
.type main,%function
.align 4
main: ;;; assume "main" starts at offset 0x20
0x0 push {r11, lr}
0x4 movw r0, :lower16:(.LAlpha-(.LBeta+8))
;;; ==> (.AddrOf(.LAlpha) - ((.AddrOf(.LBeta) - .AddrOf(".")) + 8)
;;; ==> (??? - ((16-4) + 8) = -20
0x8 movt r0, :upper16:(.LAlpha-(.LBeta+8))
;;; ==> (.AddrOf(.LAlpha) - ((.AddrOf(.LBeta) - .AddrOf(".")) + 8)
;;; ==> (??? - ((16-8) + 8) = -16
0xc ... blah
.LBeta:
0x10 add r0, pc, r0
0x14 ... blah
.LGamma:
0x18 add r1, pc, r1
Above snippet results in the following relocs in the .o file for the
first pair of movw/movt instructions
00000024 R_ARM_MOVW_PREL_NC .LAlpha
00000028 R_ARM_MOVT_PREL .LAlpha
And the encoded instructions in the .o file for main: must be
00000020 <main>:
20: e92d4800 push {fp, lr}
24: e30f0fec movw r0, #65516 ; 0xffec i.e. -20
28: e34f0ff0 movt r0, #65520 ; 0xfff0 i.e. -16
However, llc (prior to this commit) generates the following sequence
00000020 <main>:
20: e92d4800 push {fp, lr}
24: e30f0fec movw r0, #65516 ; 0xffec - i.e. -20
28: e34f0fff movt r0, #65535 ; 0xffff - i.e. -1
What has to happen in the ArmAsmBackend is that if the relocation is PC
relative, the 16 bits encoded as part of movw and movt must be both addends,
not addresses. It makes sense to encode addresses by right shifting the value
by 16, but the result is incorrect for PIC.
i.e., the right shift by 16 for movt is ONLY valid for the NON-PCRel case.
This change agrees with what GNU as does, and makes the PIC code run.
MC/ARM/elf-movt.s covers this case.
llvm-svn: 131674
An alternative syntax is available for a modified immediate constant that permits the programmer to specify
the encoding directly. In this syntax, #<const> is instead written as #<byte>,#<rot>, where:
<byte> is the numeric value of abcdefgh, in the range 0-255
<rot> is twice the numeric value of rotation, an even number in the range 0-30.
llvm-svn: 128897
also fix the encoding of the later.
- Add a new encoding bit to describe the index mode used in AM3.
- Teach printAddrMode3Operand to check by the addressing mode which
index mode to print.
- Testcases.
llvm-svn: 128832
all LDR/STR changes and left them to a future patch. Passing all
checks now.
- Implement asm parsing support for LDRT, LDRBT, STRT, STRBT and
fix the encoding wherever is possible.
- Add a new encoding bit to describe the index mode used and teach
printAddrMode2Operand to check by the addressing mode which index
mode to print.
- Testcases
llvm-svn: 128689
- Implement asm parsing support for LDRT, LDRBT, STRT, STRBT and
{STR,LDC}{2}_{PRE,POST} fixing the encoding wherever is possible.
- Move all instructions which use am2offset without a pattern to use
addrmode2.
- Add a new encoding bit to describe the index mode used and teach
printAddrMode2Operand to check by the addressing mode which index
mode to print.
- Testcases
llvm-svn: 128632
{STR,LDC}{2}_PRE.
- Fixed the encoding in some places.
- Some of those instructions were using am2offset and now use addrmode2.
Codegen isn't affected, instructions which use SelectAddrMode2Offset were not
touched.
- Teach printAddrMode2Operand to check by the addressing mode which index
mode to print.
- This is a work in progress, more work to come. The idea is to change places
which use am2offset to use addrmode2 instead, as to unify assembly parser.
- Add testcases for assembly parser
llvm-svn: 128585
Optimize trivial branches in CodeGenPrepare, which often get created from the
lowering of objectsize intrinsics. Unfortunately, a number of tests were relying
on llc not optimizing trivial branches, so I had to add an option to allow them
to continue to test what they originally tested.
This fixes <rdar://problem/8785296> and <rdar://problem/9112893>.
llvm-svn: 127498
lowering of objectsize intrinsics. Unfortunately, a number of tests were relying
on llc not optimizing trivial branches, so I had to add an option to allow them
to continue to test what they originally tested.
This fixes <rdar://problem/8785296> and <rdar://problem/9112893>.
llvm-svn: 127459
Introduce a variable in the AsmParserExtension whether [] is valid in an
expression. If it is true, parse them like (). Enable this for ELF only.
llvm-svn: 126443
- Add custom operand matching for imod and iflags.
- Rename SplitMnemonicAndCC to SplitMnemonic since it splits more than CC
from mnemonic.
- While adding ".w" as an operand, don't change "Head" to avoid passing the
wrong mnemonic to ParseOperand.
- Add asm parser tests.
- Add disassembler tests just to make sure it can catch all cps versions.
llvm-svn: 125489
When matching operands for a candidate opcode match in the auto-generated
AsmMatcher, check each operand against the expected operand match class.
Previously, operands were classified independently of the opcode being
handled, which led to difficulties when operand match classes were
more complicated than simple subclass relationships.
llvm-svn: 125245
failures with relocations.
The code committed is a first cut at compatibility for emitted relocations in
ELF .o.
Why do this? because existing ARM tools like emitting relocs symbols as
explicit relocations, not as section-offset relocs.
Result is that with these changes,
1) relocs are now substantially identical what to gcc outputs.
2) larger apps (including many spec2k tests) compile, cross-link, and pass
Added reminder fixme to tests for future conversion to .s form.
llvm-svn: 124996
(yes, this is different from R_ARM_CALL)
- Adds a new method getARMBranchTargetOpValue() which handles the
necessary distinction between the conditional and unconditional br/bl
needed for ARM/ELF
At least for ARM mode, the needed fixup for conditional versus unconditional
br/bl is identical, but the ARM docs and existing ARM tools expect this
reloc type...
Added a few FIXME's for future naming fixups in ARMInstrInfo.td
llvm-svn: 124895
qadd and qdadd uses "rd, rm, rn", the same applies to the 'sub' variants. This
is described in ARM manuals and matches the encoding used by the gnu assembler.
llvm-svn: 123975
in cdp/cdp2 instructions. Also increase the hack with cdp/cdp2 instructions.
- Fix the encoding of cdp/cdp2 instructions for ARM (no thumb and thumb2 yet) and add testcases for t
hem.
llvm-svn: 123927
Bruno Cardoso Lopes