Recently support was added for substituting one intruction for another by
negating or inverting the immediate, but ORR and ORN were missed so this patch
adds them.
This one is slightly different to the others in that ORN only exists in thumb,
so we only do the substitution in thumb.
Differential Revision: https://reviews.llvm.org/D32534
llvm-svn: 302224
- we are now using immediate AsmOperands so that the range check functions are
tablegen'ed.
- Big bonus is that error messages become much more accurate, i.e. instead of a
useless "invalid operand" error message it will not say that the immediate
operand must in range [x,y], which is why regression tests needed updating.
More tablegen operand descriptions could probably benefit from using
immediateAsmOperand, but this is a first good step to get rid of most of the
nearly identical range check functions. I will address the remaining immediate
operands in next clean ups.
Differential Revision: https://reviews.llvm.org/D31333
llvm-svn: 299358
Summary:
To support negative immediates for certain arithmetic instructions, the
instruction is converted to the inverse instruction with a negated (or inverted)
immediate. For example, "ADD r0, r1, #FFFFFFFF" cannot be encoded as an ADD
instruction. However, "SUB r0, r1, #1" is equivalent.
These conversions are different from instruction aliases. An alias maps
several assembler instructions onto one encoding. A conversion, however, maps
an *invalid* instruction--e.g. with an immediate that cannot be represented in
the encoding--to a different (but equivalent) instruction.
Several instructions with negative immediates were being converted already, but
this was not systematically tested, nor did it cover all instructions.
This patch implements all possible substitutions for ARM, Thumb1 and
Thumb2 assembler and adds tests. It also adds a feature flag
(-mattr=+no-neg-immediates) to turn these substitutions off. This is
helpful for users who want their code to assemble to exactly what they
wrote.
Reviewers: t.p.northover, rovka, samparker, javed.absar, peter.smith, rengolin
Reviewed By: javed.absar
Subscribers: aadg, aemerson, llvm-commits
Differential Revision: https://reviews.llvm.org/D30571
llvm-svn: 298380
John Brawn