[turbofan] Add support for reinterpreting integers as floating point and vice versa.

[turbofan] Add support for reinterpreting integers as floating point and vice versa.

R=bmeurer@chromium.org

Committed: https://crrev.com/c610a22231212b12055c294f55b8f3942127580b
Cr-Commit-Position: refs/heads/master@{#30849}

[Benedikt Meurer, 2015-09-19 16:55:38]

Can you move the instruction codes to the ARCH_OPCODE_LIST in
instruction-codes.h, because they are available on every platform (the F64<->I64
can be turned into UNREACHABLE() in the 32-bit platforms CodeGenerators for
now)?

And one more nit: Can we name these "bit casts" instead of "reinterpret"? I.e.
maybe BitCastFloat64ToInt64, and so on? I think that would make their use a bit
clearer (actually matching the LLVM name then).

[titzer, 2015-09-21 13:34:17]

On 2015/09/19 16:55:38, Benedikt Meurer wrote:
> Can you move the instruction codes to the ARCH_OPCODE_LIST in
> instruction-codes.h, because they are available on every platform (the
F64<->I64
> can be turned into UNREACHABLE() in the 32-bit platforms CodeGenerators for
> now)?

The opcodes are a little different on each platform and I was actually tempted
to follow the assembler names more closely, e.g. on MIPS. I also cheated a
little and reused parts of the instructions used for extracting high and low
words of floats...

> And one more nit: Can we name these "bit casts" instead of "reinterpret"? I.e.
> maybe BitCastFloat64ToInt64, and so on? I think that would make their use a
bit
> clearer (actually matching the LLVM name then).

I've renamed them to BitcastXToY.

[Benedikt Meurer, 2015-09-21 13:35:21]

LGTM, thanks.

[titzer, 2015-09-21 13:59:05]

The CQ bit was checked by titzer@chromium.org

[commit-bot: I haz the power, 2015-09-21 13:59:17]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1356913002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1356913002/20001

[commit-bot: I haz the power, 2015-09-21 14:00:55]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-21 14:01:14]

Patchset 2 (id:??) landed as
https://crrev.com/c610a22231212b12055c294f55b8f3942127580b
Cr-Commit-Position: refs/heads/master@{#30849}