Summary:
This patch fixes pr23772 [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).
Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma, andreadb
Reviewed By: efriedma
Subscribers: gbedwell, john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70680
Summary:
This patch fixes pr23772 [ARM] r226200 can emit illegal thumb2 instruction: "sub sp, r12, #80".
The violation was that SUB and ADD (reg, immediate) instructions can only write to SP if the source register is also SP. So the above instructions was unpredictable.
To enforce that the instruction t2(ADD|SUB)ri does not write to SP we now enforce the destination register to be rGPR (That exclude PC and SP).
Different than the ARM specification, that defines one instruction that can read from SP, and one that can't, here we inserted one that can't write to SP, and other that can only write to SP as to reuse most of the hard-coded size optimizations.
When performing this change, it uncovered that emitting Thumb2 Reg plus Immediate could not emit all variants of ADD SP, SP #imm instructions before so it was refactored to be able to. (see test/CodeGen/Thumb2/mve-stacksplot.mir where we use a subw sp, sp, Imm12 variant )
It also uncovered a disassembly issue of adr.w instructions, that were only written as SUBW instructions (see llvm/test/MC/Disassembler/ARM/thumb2.txt).
Reviewers: eli.friedman, dmgreen, carwil, olista01, efriedma
Reviewed By: efriedma
Subscribers: john.brawn, efriedma, ostannard, kristof.beyls, hiraditya, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70680
The manual says that Thumb2 add/sub instructions are only allowed to modify sp
if the first source is also sp. This is slightly different from the usual rGPR
restriction since it's context-sensitive, so implement it in C++.
llvm-svn: 358987
ARMDisassembler now depends on the banked register tables in ARMUtils, so the
LLVMBuild.txt needed updating to reflect this.
Original commit mesage:
[ARM] Fix disassembly of invalid banked register moves
When disassembling banked register move instructions, we don't have an
assembly syntax for the unallocated register numbers, so we have to
return Fail rather than SoftFail. Previously we were returning SoftFail,
then crashing in the InstPrinter as we have no way to represent these
encodings in an assembly string.
This also switches the decoder to use the table-generated list of banked
registers, removing the duplicated list of encodings.
Differential revision: https://reviews.llvm.org/D43066
llvm-svn: 324606
The broken bot (clang-ppc64le-linux-multistage) is doign a shared-object build,
so I guess using lookupBankedRegByEncoding in the disassembler is a layering
violation?
llvm-svn: 324604
When disassembling banked register move instructions, we don't have an
assembly syntax for the unallocated register numbers, so we have to
return Fail rather than SoftFail. Previously we were returning SoftFail,
then crashing in the InstPrinter as we have no way to represent these
encodings in an assembly string.
This also switches the decoder to use the table-generated list of banked
registers, removing the duplicated list of encodings.
Differential revision: https://reviews.llvm.org/D43066
llvm-svn: 324600
Summary:
This patch handles assembly and disassembly, but not codegen, as of yet.
Additionally, it fixes a bug whereby SP and PC as shifted-reg operands
were treated as predictable in ARMv7 Thumb; and it enables the tests
for invalid and unpredictable instructions to run on both ARMv7 and ARMv8.
Reviewers: jmolloy, rengolin
Subscribers: aemerson, rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D14141
llvm-svn: 251516
The UDF instruction is a reserved undefined instruction space. The assembler
mnemonic was introduced with ARM ARM rev C.a. The instruction is not predicated
and the immediate constant is ignored by the CPU. Add support for the three
encodings for this instruction.
The changes to the invalid instruction test is due to the fact that the invalid
instructions actually overlap with the undefined instruction. Introduction of
the new instruction results in a partial decode as an undefined sequence. Drop
the tests as they are invalid instruction patterns anyways.
llvm-svn: 208751
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
This allows "llvm-mc -disassemble" to accept two new features:
+ Using comma as a byte separator
+ Grouping bytes with '[' and ']' pairs.
The behaviour outside a [...] group is unchanged. But within the group once
llvm-mc encounters a true error, it stops rather than trying to resynchronise
the stream at the next byte. This is more useful for disassembly tests, where
we have an almost-instruction in mind and don't care what the misaligned
interpretation would be. Particularly if it means llvm-mc won't actually see
the next intended almost-instruction.
As a side effect, this means llvm-mc can disassemble its own -show-encoding
output if copy-pasted.
llvm-svn: 186661
Diogo Sampaio