TableGen: NumResults <= 1 restriction

Project Infrastructure LLVM Dev List Archives
1

Hi all,

i’m working atm on a backend for a processor architecture that is capable of storing the carry flag of ADDC in an 1-bit register class. So I tried to lower the ADDC instruction to generate two register values as result. On the tablegen description of the instruction i came across the tablegen restriction that only one output result of one instruction is possible:

assert(NumResults <= 1 &&

“We only work with nodes with zero or one result so far!”);

So my question is now how much work it would be to remove this restriction in tablegen. What do I have to take into consideration?

Thanks,

Timo Stripf

2

I don’t know offhand, but this would be a very welcome improvement!

-Chris

3

Quoting Chris Lattner <clattner@apple.com>:

Dear staff,
     I am using the ds-aa to pass mysqld. I compile mysqld 4.0.12 statically (compile all libraries statically to the executable) and got the bc file, named it as mysqld.bc3.
     I use the command to pass:

opt -load <poolalloc install dir>/lib/libLLVMDataStructure.so -ds-aa mysqld.bc3 -print-alias-sets -disable-output

     However, I got a lot of "cast in ... " on output screen like this:

cast in strxnmov
         %13 = inttoptr i32 %10 to i8* ; <i8*> [#uses=1]

     In addition, and pass can not stop for a long time, and the last output is the "cast in ... " as above.

Thanks,
Heming

4

Quoting hc2428@columbia.edu:

Dear staff,
     Here is the bc file.

Heming

mysqld.bc3.tar.gz (2.67 MB)

5

Quoting hc2428@columbia.edu:

Dear staff,
     I try to use anders-aa to pass the mysqld.bc3 in my previous email, but it does not work.

Command: opt -anders-aa mysqld.bc3 -disable-output

Output:
Unknown instruction: %mrv4 = insertvalue %struct.ACL_ACCESS undef, i64 %mrv, 0 ; <%struct.ACL_ACCESS> [#uses=1]
opt[0x9e886c]
opt[0x9e898e]
/lib/libc.so.6[0x7fb96ab8b100]
/lib/libc.so.6(gsignal+0x35)[0x7fb96ab8b095]
/lib/libc.so.6(abort+0x110)[0x7fb96ab8caf0]
opt[0x875c8a]
opt[0x876149]
opt[0x876169]
opt[0x87a331]
opt[0x87a38f]
opt[0x87a3e4]
opt[0x87a429]
opt[0x87a47e]
opt[0x87a4a3]
opt[0x87a8c8]
opt[0x87ab50]
opt(_ZN4llvm13MPPassManager11runOnModuleERNS_6ModuleE+0xba)[0x977982]
opt(_ZN4llvm15PassManagerImpl3runERNS_6ModuleE+0x74)[0x979296]
opt(_ZN4llvm11PassManager3runERNS_6ModuleE+0x21)[0x9792f9]
opt(main+0xf7e)[0x6c4ae6]
/lib/libc.so.6(__libc_start_main+0xf4)[0x7fb96ab771c4]
opt(cos+0x119)[0x6b5089]
Aborted

6

Quoting Chris Lattner <clattner@apple.com>:

Dear staff,
I am using the ds-aa to pass mysqld. I compile mysqld 4.0.12
statically (compile all libraries statically to the executable) and
got the bc file, named it as mysqld.bc3.
I use the command to pass:

opt -load <poolalloc install dir>/lib/libLLVMDataStructure.so -ds-aa
mysqld.bc3 -print-alias-sets -disable-output

However, I got a lot of &quot;cast in \.\.\. &quot; on output screen like this:

cast in strxnmov
%13 = inttoptr i32 %10 to i8* ; <i8*> [#uses=1]

In addition, and pass can not stop for a long time, and the last

output is the "cast in ... " as above.

inttoptr casts are very bad for alias analysis. DSA has some code in
it these days to try to track common inttoptr idioms, but this code
likely doesn't scale well.

Andrew

7

Quoting Andrew Lenharth <andrewl@lenharth.org>:

Hi Andrew,
     Thanks for your reply. How can I eliminate the inttoptr instruction from my software? Can any compile option achieve this goal? Or shall I modify the source code in software manually?

Thanks,
Heming