Subzero: Fix x86 lowering for shift-by-relocatable-constant.

Subzero: Fix x86 lowering for shift-by-relocatable-constant.

Trying to shift by a ConstantRelocatable causes an assertion failure in the integrated assembler, because the shift value must be Imm8.  Maybe this is possible to express via ELF relocations, but it doesn't seem worth it.  Especially since ConstantRelocatables refer to addresses and it doesn't make sense to shift by an address.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4256
R=jvoung@chromium.org, kschimpf@google.com

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=c5c8957b40d115daa7f4806bd7e5b59fe31b8aa8

[Jim Stichnoth, 2015-08-04 18:45:26]

stichnot@chromium.org changed reviewers:
+ jpp@chromium.org, jvoung@chromium.org, kschimpf@google.com

[Karl, 2015-08-04 19:37:37]

lgtm

[jvoung (off chromium), 2015-08-04 21:21:51]

lgtm

https://codereview.chromium.org/1262003003/diff/1/tests_lit/llvm2ice_tests/ar...
File tests_lit/llvm2ice_tests/arith.ll (right):

https://codereview.chromium.org/1262003003/diff/1/tests_lit/llvm2ice_tests/ar...
tests_lit/llvm2ice_tests/arith.ll:223: ; CHECK: shl {{.*}},cl
Yeah I agree with the reloc awkwardness, especially since the operand is
restricted to 8-bit reg or 8-bit imm =/

[Jim Stichnoth, 2015-08-04 22:26:53]

Committed patchset #1 (id:1) manually as
c5c8957b40d115daa7f4806bd7e5b59fe31b8aa8 (presubmit successful).