PPC: [turbofan] Introduce integer multiplication with overflow.

PPC: [turbofan] Introduce integer multiplication with overflow.

Port 8e18a5f2a0357c6899cd32f5ab66b73d72fdd996

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=

Committed: https://crrev.com/f6c45c5243646a2a2da7bc113971c3b439323ac3
Cr-Commit-Position: refs/heads/master@{#37812}

[john.yan, 2016-07-16 03:54:45]

https://codereview.chromium.org/2152363002/diff/1/src/compiler/ppc/code-gener...
File src/compiler/ppc/code-generator-ppc.cc (right):

https://codereview.chromium.org/2152363002/diff/1/src/compiler/ppc/code-gener...
src/compiler/ppc/code-generator-ppc.cc:1313: break;
Try this sequence here:
 +    case kPPC_Mul32WithHigh32:
 +      if (i.OutputRegister(0).is(i.InputRegister(0)) ||
 +          i.OutputRegister(0).is(i.InputRegister(1)) ||
 +          i.OutputRegister(1).is(i.InputRegister(0)) ||
 +          i.OutputRegister(1).is(i.InputRegister(1))) {
 +        __ mullw(kScratchReg,
 +                 i.InputRegister(0), i.InputRegister(1));  // low
 +        __ mulhw(i.OutputRegister(1),
 +                 i.InputRegister(0), i.InputRegister(1));  // high
 +        __ mr(i.OutputRegister(0), kScratchReg);
 +      } else {
 +        __ mullw(i.OutputRegister(0),
 +                 i.InputRegister(0), i.InputRegister(1));  // low
 +        __ mulhw(i.OutputRegister(1),
 +                 i.InputRegister(0), i.InputRegister(1));  // high
 +      }
 +      break;

[john.yan, 2016-07-16 03:57:48]

https://codereview.chromium.org/2152363002/diff/1/src/compiler/ppc/code-gener...
File src/compiler/ppc/code-generator-ppc.cc (right):

https://codereview.chromium.org/2152363002/diff/1/src/compiler/ppc/code-gener...
src/compiler/ppc/code-generator-ppc.cc:1308: case kPPC_Mul32WithHigh32:
The reason why this fails is that output reg can be one of the input reg.
Therefore, mullw could be modifying one of the input reg, which causes mulhw to
produce incorrect output.

[john.yan, 2016-07-18 03:14:45]

lgtm

[JaideepBajwa, 2016-07-18 03:16:38]

The CQ bit was checked by bjaideep@ca.ibm.com

[commit-bot: I haz the power, 2016-07-18 03:16:42]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-18 03:40:17]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-07-18 03:42:13]

Description was changed from

==========
PPC: [turbofan] Introduce integer multiplication with overflow.

Port 8e18a5f2a0357c6899cd32f5ab66b73d72fdd996

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
==========

to

==========
PPC: [turbofan] Introduce integer multiplication with overflow.

Port 8e18a5f2a0357c6899cd32f5ab66b73d72fdd996

R=mvstanton@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com,
michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=

Committed: https://crrev.com/f6c45c5243646a2a2da7bc113971c3b439323ac3
Cr-Commit-Position: refs/heads/master@{#37812}
==========

[commit-bot: I haz the power, 2016-07-18 03:42:14]

Patchset 2 (id:??) landed as
https://crrev.com/f6c45c5243646a2a2da7bc113971c3b439323ac3
Cr-Commit-Position: refs/heads/master@{#37812}