Subzero. Fixes ARM32 VFP calling convention.

Fixes ARM32 VFP calling convention.

Packs VFP arguments as tight as the ABI wants, and adds tests for
float and double arguments. vector argument tests will come soon.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=stichnot@chromium.org

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=385351bab561a0992dbbfe617bf5f81f58db1674

[John, 2015-09-16 21:09:27]

jpp@chromium.org changed reviewers:
+ stichnot@chromium.org

[Jim Stichnoth, 2015-09-16 21:31:54]

Calling this "fixes register allocation" conveys to me something completely
different than what the CL actually does.  Can it be something like "Fixes ARM32
FP register calling convention"?

Otherwise lgtm since I don't think the crosstest is possible yet.

https://codereview.chromium.org/1348393002/diff/1/src/IceInstARM32.cpp
File src/IceInstARM32.cpp (right):

https://codereview.chromium.org/1348393002/diff/1/src/IceInstARM32.cpp#newcod...
src/IceInstARM32.cpp:544: bool isVariableWithoutRegister(Operand *Op) {
Consider declaring these as const Operand * ?

https://codereview.chromium.org/1348393002/diff/1/src/IceTargetLoweringARM32.h
File src/IceTargetLoweringARM32.h (right):

https://codereview.chromium.org/1348393002/diff/1/src/IceTargetLoweringARM32....
src/IceTargetLoweringARM32.h:467: /// assignments. The first few integer type
parameters can use r0-r3,
Is there a public reference that you can cite here for the interested reader?

https://codereview.chromium.org/1348393002/diff/1/src/IceTargetLoweringARM32....
src/IceTargetLoweringARM32.h:485: for (uint32_t i = 0; i <
ARM32_MAX_FP_REG_UNITS; ++i) {
Whoa!  This is almost FizzBuzz!
:)

https://codereview.chromium.org/1348393002/diff/1/tests_lit/llvm2ice_tests/fp...
File tests_lit/llvm2ice_tests/fp.arm.call.ll (right):

https://codereview.chromium.org/1348393002/diff/1/tests_lit/llvm2ice_tests/fp...
tests_lit/llvm2ice_tests/fp.arm.call.ll:1: ; Tests validating the vfp calling
convention for ARM32.
Is it possible yet to enable crosstest/test_calling_conv?  Maybe not, if the
vector constants in the test are simplified to insertelement instructions?

[John, 2015-09-16 23:11:15]

Committed patchset #1 (id:1) manually as
385351bab561a0992dbbfe617bf5f81f58db1674 (presubmit successful).

[John, 2015-09-16 23:12:47]

https://codereview.chromium.org/1348393002/diff/1/src/IceInstARM32.cpp
File src/IceInstARM32.cpp (right):

https://codereview.chromium.org/1348393002/diff/1/src/IceInstARM32.cpp#newcod...
src/IceInstARM32.cpp:544: bool isVariableWithoutRegister(Operand *Op) {
On 2015/09/16 21:31:54, stichnot wrote:
> Consider declaring these as const Operand * ?

Done.

https://codereview.chromium.org/1348393002/diff/1/src/IceTargetLoweringARM32.h
File src/IceTargetLoweringARM32.h (right):

https://codereview.chromium.org/1348393002/diff/1/src/IceTargetLoweringARM32....
src/IceTargetLoweringARM32.h:467: /// assignments. The first few integer type
parameters can use r0-r3,
On 2015/09/16 21:31:54, stichnot wrote:
> Is there a public reference that you can cite here for the interested reader?

Done.

https://codereview.chromium.org/1348393002/diff/1/tests_lit/llvm2ice_tests/fp...
File tests_lit/llvm2ice_tests/fp.arm.call.ll (right):

https://codereview.chromium.org/1348393002/diff/1/tests_lit/llvm2ice_tests/fp...
tests_lit/llvm2ice_tests/fp.arm.call.ll:1: ; Tests validating the vfp calling
convention for ARM32.
On 2015/09/16 21:31:54, stichnot wrote:
> Is it possible yet to enable crosstest/test_calling_conv?  Maybe not, if the
> vector constants in the test are simplified to insertelement instructions?

Not yet. Vector types are not handled at all, and some other lowerings are still
unimplemented.