FIX the assembly format of the x86 backend to make both clang and gcc happy

[sheisc]

Summary

The GNU assembler (used in gcc) complains about the syntactic correctness of
the assembly code (at line 9) generated by clang (with the option -no-integrated-as).

We need to delete the white space in "{%k1} {z}" (at line 9) to make both GCC and LLVM happy.

iron@CSE:demo$ cat -n main.s

 1		.text
 2		.file	"main.c"
 3		.globl	main                    # -- Begin function main
 4		.p2align	4, 0x90
 5		.type	main,@function
 6	main:                                   # @main
 7		.cfi_startproc
 8	# %bb.0:                                # %entry
 9		vmovdqu16 %zmm5 , %zmm5 {%k1} {z}
10		xorl	%eax, %eax
11		retq
12	.Lfunc_end0:
13		.size	main, .Lfunc_end0-main
14		.cfi_endproc
15	                                        # -- End function
16
17		.ident	"clang"
18		.section	".note.GNU-stack","",@progbits

iron@CSE:demo$ clang -c main.s -o main.o

iron@CSE:demo$ gcc -c main.s -o main.o

main.s: Assembler messages:
main.s:9: Error: unknown vector operation: ` {z}'

[pengfei]

I guess a lot of lines of tests need to update

$ grep -rn " {z}" llvm/test/CodeGen/X86/ | wc -l
7797

clang/docs/ReleaseNotes.rst

368 ↗

(On Diff #430052)

I think this can be a sepreate patch. Or commit directly with a NFC label.

llvm/lib/Target/X86/MCTargetDesc/X86InstComments.cpp

279

Fix the comment as well.

[pengfei]

I think another way is to report the issue to GCC. From the perspective of the user, GCC should support both {%k1} {z} and {%k1}{z}. Then we don't need the clange on LLVM.

[sheisc]

In D125789#3519361, @pengfei wrote:

I guess a lot of lines of tests need to update

$ grep -rn " {z}" llvm/test/CodeGen/X86/ | wc -l
7797

Thanks.
Yes. It seems to be a big revision, caused by only one white space :)

[sheisc]

In D125789#3519411, @pengfei wrote:

I think another way is to report the issue to GCC. From the perspective of the user, GCC should support both {%k1} {z} and {%k1}{z}. Then we don't need the clange on LLVM.

Yes. It is a good idea.
However, it appears that there is no such white space in the instructions as described in Intel's manuals.
So I don't know which one should be the correct format.
Anyway, not a big issue.
I found this problem when using the fuzzer (i.e. AFL) to build Firefox.

[pengfei]

In D125789#3519433, @sheisc wrote:

In D125789#3519411, @pengfei wrote:

I think another way is to report the issue to GCC. From the perspective of the user, GCC should support both {%k1} {z} and {%k1}{z}. Then we don't need the clange on LLVM.

Yes. It is a good idea.
However, it appears that there is no such white space in the instructions as described in Intel's manuals.
So I don't know which one should be the correct format.
Anyway, not a big issue.
I found this problem when using the fuzzer (i.e. AFL) to build Firefox.

Yeah. This is an interesting question. I didn't notice the difference between LLVM and GCC. I think either way changing here or GCC is OK :)

[sheisc]

In D125789#3519493, @pengfei wrote:

In D125789#3519433, @sheisc wrote:

In D125789#3519411, @pengfei wrote:

I think another way is to report the issue to GCC. From the perspective of the user, GCC should support both {%k1} {z} and {%k1}{z}. Then we don't need the clange on LLVM.

Yes. It is a good idea.
However, it appears that there is no such white space in the instructions as described in Intel's manuals.
So I don't know which one should be the correct format.
Anyway, not a big issue.
I found this problem when using the fuzzer (i.e. AFL) to build Firefox.

Yeah. This is an interesting question. I didn't notice the difference between LLVM and GCC. I think either way changing here or GCC is OK :)

Hi Pengfei,

Thanks a lot. The guys in the GCC community can make our life easier by supporting the white space.

[craig.topper]

Is it gcc that needs a fix or binutils?

[sheisc]

In D125789#3519538, @craig.topper wrote:

Is it gcc that needs a fix or binutils?

Yes. Exactly speaking, it is the GNU assembler in binutils.
https://www.gnu.org/software/binutils/

llvm/lib/Target/X86/MCTargetDesc/X86InstComments.cpp

 
   // MASKZ: zmmX {%kY} {z}
   if (MaskWithZero)
-    OS << " {z}";
+    OS << "{z}";
 }
 
 static bool printFMAComments(const MCInst *MI, raw_ostream &OS,

llvm/lib/Target/X86/X86MCInstLower.cpp

       CS << " {%" << GetRegisterName(WriteMaskOp.getReg()) << "}";
 
       if (SrcOp1Idx == 2) {
-        CS << " {z}";
+        CS << "{z}";
       }
     }
   }