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[X86] Add combination for fma and fneg on X86 under strict FP.
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Authored by pengfei on Jan 15 2020, 9:55 PM.

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Summary

X86 has instructions to calculate fma and fneg at the same time. But we combine the fneg and fma only when fneg is the source operand under strict FP.

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pengfei created this revision.Jan 15 2020, 9:55 PM
pengfei updated this revision to Diff 238425.Jan 16 2020, 12:43 AM

Add FMA4 tests. Thanks @RKSimon.

Add to isNegatibleForFree/getNegatedExpression as well?

Add to isNegatibleForFree/getNegatedExpression as well?

We don't need to add them to isNegatibleForFree/getNegatedExpression. We won't negate any FMA results by negative FMA instructions under strict FP, because fneg(FMA) has different result from FNMA under some rounding mode.

Add to isNegatibleForFree/getNegatedExpression as well?

We don't need to add them to isNegatibleForFree/getNegatedExpression. We won't negate any FMA results by negative FMA instructions under strict FP, because fneg(FMA) has different result from FNMA under some rounding mode.

Thanks for confirming - no more comments from me.

Are we missing tests for the vector instructions?

pengfei updated this revision to Diff 240472.Jan 26 2020, 8:09 PM

Rebase and add vector instructions test.

This revision is now accepted and ready to land.Jan 27 2020, 10:33 PM
This revision was automatically updated to reflect the committed changes.