[PATCH] D33312: [Sparc] Do not encode the 2 LSBs of the address in the call instruction

[James Y Knight via Phabricator via llvm-commits]

jyknight added a comment.

The current behavior is definitely wrong...but I think this isn't a correct fix either.

Per the behavior of both GNU as and Solaris as, "call NUM" should actually be an alias for "jmpl NUM, %o7", so I think isImm shouldn't be supported in getCallTargetOpValue at all -- and the tabledefs should be modified so that it's impossible to get into that code with an immediate.

(While I look at this, though, I notice that the *disassembly* is bogus in both gnu "objdump" and solaris "dis". They both output a relative call using the text "call NUM" -- they print a relative call using syntax which is parsed on input as an absolute call. Ugh. llvm-objdump at least prints the two differently and basically consistent with the assembler, but its assembler is wrong.)

Given a test file test.s:

  call 1
  call 4
  call 0x1232
  call . + 1
  call . + 4
  call . + 0x1232

With GNU as: "as -o test.o test.s". Note the difference in instruction encodings for the first 3 vs last 3. (I note also that "call . + 1" should really be an error, since it's unencodable, but that's a different issue.)

"objdump -d test.o":

  00000000 <.text>:
     0:   9f c0 20 01     call  1
     4:   9f c0 20 04     call  4
     8:   9f c0 24 d2     call  0x4d0
     c:   40 00 00 00     call  0xc
    10:   40 00 00 01     call  0x14
    14:   40 00 01 34     call  0x4e4

"llvm-objdump -d test.o":

  .text:
         0:       9f c0 20 01     call %g0+1
         4:       9f c0 20 04     call %g0+4
         8:       9f c0 24 d2     call %g0+1232
         c:       40 00 00 00     call 0
        10:       40 00 00 01     call 4
        14:       40 00 01 34     call 1232

With "clang -fintegrated-as -c -target sparc-unknown-unknown -o test.o test.s", note that we incorrectly encoded everything as relative calls.

"objdump -d test.o":

  00000000 <.text>:
     0:   40 00 00 01     call  0x4
     4:   40 00 00 04     call  0x14
     8:   40 00 04 d2     call  0x1350
     c:   40 00 00 00     call  0xc
    10:   40 00 00 01     call  0x14
    14:   40 00 01 34     call  0x4e4


https://reviews.llvm.org/D33312