integrated assembler should convert and foo, bar, immediate into bic foo, bar, ~immediate if immediate doesn't fit into the immediate field bit ~immediate does

[nico]

Bugzilla Link	25720
Resolution	FIXED
Resolved on	Dec 08, 2015 12:11
Version	trunk
OS	Linux
Blocks	#20796
CC	@Arnaud-de-Grandmaison-ARM,@jmolloy,@rengolin,@TNorthover

Extended Description

When trying to build boringssl with clang's integrated assembler, it complains about this:

thakis@thakis:/src/chrome/src$ cat arm.S
.fpu neon
.text
.align 4
.global foo
.hidden foo
.type foo, %function
and sp, sp, #​0xffffffe0
thakis@thakis:/src/chrome/src$ third_party/llvm-build/Release+Asserts/bin/clang -c arm.S -march=armv7-a -target arm-linux-androideab
arm.S:7:14: error: invalid operand for instruction
and sp, sp, #​0xffffffe0
^

gas accepts this without complaints and converts it into a BIC instruction (a and not b), as ~0xffffffe0 = 1f fits into the 8bit unshifted immediate. The integrated assembler should do this too:

thakis@thakis:/src/chrome/src$ third_party/android_tools/ndk/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-gcc -c arm.S
thakis@thakis:/src/chrome/src$ third_party/android_tools/ndk/toolchains/arm-linux-androideabi-4.8/prebuilt/linux-x86_64/bin/arm-linux-androideabi-objdump -D -marm arm.o

arm.o: file format elf32-littlearm

Disassembly of section .text:

00000000 <.text>:
0: e3cdd01f bic sp, sp, #​31
4: e1a00000 nop ; (mov r0, r0)
8: e1a00000 nop ; (mov r0, r0)
c: e1a00000 nop ; (mov r0, r0)

[nico]

assigned to @rengolin

[TNorthover]

Implementation will obviously have to make sure the real AND gets prioritised if both forms are valid, but this seems likely to be a fairly simple and uncontroversial one to implement.

[rengolin]

So, it appears support was added many years ago, and the only problem with your example wasn't the negative, but the use of SP, which wasn't included in the pattern. I'll be submitting a patch soon.

[TNorthover]

Ah, that would explain why the whole thing seemed familiar!

[rengolin]

Expanded to all registers (on ARM only) in r255034, with some more tests. Your example works now.