Certain ARM instructions accept 32-bit immediate operands encoded as a 8-bit
integer value (0-255) and a 4-bit rotation (0-30, even). Current ARM assembly
syntax support in LLVM allows the decoded (32-bit) immediate to be specified
as a single immediate operand for such instructions:
mov r0, #4278190080
The ARMARM defines an extended assembly syntax allowing the encoding to be made
more explicit, as in:
mov r0, #255, #8 ; (same 32-bit value as above)
The behaviour of the two instructions can be different w.r.t flags, which is
documented under "Modified immediate constants" in ARMARM. This patch enables
support for this extended syntax at the MC layer.
llvm-svn: 223113
The ARM ARM prohibits LDRB/LDRSB instructions with writeback into the destination register. With this commit this constraint is now enforced and we stop assembling LDRH/LDRSH instructions with unpredictable behavior.
llvm-svn: 214500
The ARM ARM prohibits LDRH/LDRSH instructions with writeback into the source register. With this commit this constraint is now enforced and we stop assembling LDRH/LDRSH instructions with unpredictable behavior.
llvm-svn: 214499
The ARM ARM prohibits LDR instructions with writeback into the destination register. With this commit this constraint is now enforced and we stop assembling LDR instructions with unpredictable behavior.
llvm-svn: 214498
The ARM ARM prohibits STRH instructions with writeback into the source register. With this commit this constraint is now enforced and we stop assembling STRH instructions with unpredictable behavior.
llvm-svn: 213850
The ARM ARM prohibits STRB instructions with writeback into the source register. With this commit this constraint is now enforced and we stop assembling STRB instructions with unpredictable behavior.
llvm-svn: 213750
The ARM ARM prohibits STR instructions with writeback into the source register. With this commit this constraint is now enforced and we stop assembling STR instructions with unpredictable behavior.
llvm-svn: 213745
Strictly, it's unpredictable. But we don't quite model that yet and an error is
better than ignoring the issue. This one somehow got left out before though.
rdar://problem/15997748
llvm-svn: 211490
expressions for mov instructions instead of silently truncating by default.
For the ARM assembler, we want to avoid misleadingly allowing something
like "mov r0, <symbol>" especially when we turn it into a movw and the
expression <symbol> does not have a :lower16: or :upper16" as part of the
expression. We don't want the behavior of silently truncating, which can be
unexpected and lead to bugs that are difficult to find since this is an easy
mistake to make.
This does change the previous behavior of llvm but actually matches an
older gnu assembler that would not allow this but print less useful errors
of like “invalid constant (0x927c0) after fixup” and “unsupported relocation on
symbol foo”. The error for llvm is "immediate expression for mov requires
:lower16: or :upper16" with correct location information on the operand
as shown in the added test cases.
rdar://12342160
llvm-svn: 206669
The system LDM and STM instructions can't usually writeback to the base
register. The one exception is when an LDM is actually an exception-return
(i.e. contains PC in the register list).
(There's already a test that "ldm sp!, {r0-r3, pc}^" works, which is why there
is no positive test).
rdar://problem/15223374
llvm-svn: 194512
If an alias inherits directly from InstAlias then it doesn't get any default
"Requires" values, so llvm-mc will allow it even on architectures that don't
support the underlying instruction.
This tidies up the obvious VFP and NEON cases I found.
llvm-svn: 193340
POP instructions are aliased to the ARM LDM variants but have different syntax.
This caused two problems: we tried to access a non-existent operand to annotate
the '!', and the error message didn't make much sense.
With some vigorous hand-waving in the error message both problems can be
fixed.
llvm-svn: 193322
The set of circumstances where the writeback register is allowed to be in the
list of registers is rather baroque, but I think this implements them all on
the assembly parsing side.
For disassembly, we still warn about an ARM-mode LDM even if the architecture
revision is < v7 (the required architecture information isn't available). It's
a silly instruction anyway, so hopefully no-one will mind.
rdar://problem/15223374
llvm-svn: 193185
These were pretty straightforward instructions, with some assembly support
required for HLT.
The ARM assembler is keen to split the instruction mnemonic into a
(non-existent) 'H' instruction with the LT condition code. An exception for
HLT is needed.
HLT follows the same rules as BKPT when in IT blocks, so the special BKPT
hadling code has been adapted to handle HLT also.
Regression tests added including diagnostic tests for out of range immediates
and illegal condition codes, as well as negative tests for pre-ARMv8.
llvm-svn: 190053
Unfortunately this addresses two issues (by the time I'd disentangled the logic
it wasn't worth putting it back to half-broken):
+ Coprocessor instructions should all be predicable in Thumb mode.
+ BKPT should never be predicable.
llvm-svn: 184965
"When assembling to the ARM instruction set, the .N qualifier produces
an assembler error and the .W qualifier has no effect."
In the pre-matcher handler in the asm parser the ".w" (wide) qualifier
when in ARM mode is now discarded. And an error message is now
produced when the ".n" (narrow) qualifier is used in ARM mode.
Test cases for these were added.
rdar://14064574
llvm-svn: 184224
This patch fixes load/store instructions to handle less common cases
like "asr #32", "rrx" properly throughout the MC layer.
Patch by Chris Lidbury.
llvm-svn: 164455
As an example of how the custom DiagnosticType can be used to provide
better operand-mismatch diagnostics, add a custom diagnostic for
the imm0_15 operand class used for several system instructions.
Update the tests to expect the improved diagnostic.
rdar://8987109
llvm-svn: 159051
It's not a good style idea, as the registers will be laid down in memory in
numerical order, not the order they're in the list, but it's legal. vldm/vstm
are stricter.
rdar://11064740
llvm-svn: 152943
Clean up register list handling in general a bit to explicitly check things
like all the registers being from the same register class.
rdar://8883573
llvm-svn: 139707
Encode the width operand as it encodes in the instruction, which simplifies
the disassembler and the encoder, by using the imm1_32 operand def. Add a
diagnostic for the context-sensitive constraint that the width must be in
the range [1,32-lsb].
llvm-svn: 136264
Fix the Rn register encoding for both SSAT and USAT. Update the parsing of the
shift operand to correctly handle the allowed shift types and immediate ranges
and issue meaningful diagnostics when an illegal value or shift type is
specified. Add aliases to parse an ommitted shift operand (default value of
'lsl #0').
Add tests for diagnostics and proper encoding.
llvm-svn: 135990
Correct the handling of the 's' suffix when parsing ARM mode. It's only a
truly separate opcode in Thumb. Add test cases to make sure we handle
the s and condition suffices correctly, including diagnostics.
llvm-svn: 135513
Add range checking for the immediate operand and handle the "mov" mnemonic
choosing between encodings based on the value of the immediate. Add tests
for fixups, encoding choice and values, and diagnostic for out of range values.
llvm-svn: 135500
Catch potential cascading errors on a malformed so_reg operand and bail after
the first error.
Add some tests for the diagnostics we do want.
llvm-svn: 135055
