[DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold
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Authored by lebedev.ri on May 30 2019, 7:11 AM.

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RKSimon
spatel
craig.topper
t.p.northover

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rGcc9a9cf23784: [DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold
rL362131: [DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold

Summary

This was the root cause of the endless combine loop in D62257

https://rise4fun.com/Alive/d3W

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Repository: rL LLVM

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lebedev.ri created this revision.May 30 2019, 7:11 AM

Herald added a subscriber: javed.absar. · View Herald TranscriptMay 30 2019, 7:11 AM

lebedev.ri added a parent revision: D62661: [DAGCombine] Use FoldConstantArithmetic() to perform ((c1-A)+c2) -> (c1+c2)-A fold.May 30 2019, 7:12 AM

lebedev.ri added a child revision: D62663: [DAGCombine] Use FoldConstantArithmetic() to perform C2-(A+C1) -> (C2-C1)-A fold.

lebedev.ri mentioned this in D62664: [DAGCombine] (A+C1)-C2 -> A+(C1-C2) constant-fold.May 30 2019, 7:14 AM

Better test coverage

And actually fix the test coverage (:
Sorry for the noise.

LGTM.

This revision is now accepted and ready to land.May 30 2019, 9:54 AM

Closed by commit rL362131: [DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold (authored by lebedevri). · Explain WhyMay 30 2019, 12:24 PM

This revision was automatically updated to reflect the committed changes.

Diffusion mentioned this in rL362133: [DAGCombine] (A+C1)-C2 -> A+(C1-C2) constant-fold.

lebedev.ri mentioned this in rG0a3dbbcdfb54: [DAGCombine] (A+C1)-C2 -> A+(C1-C2) constant-fold.May 30 2019, 12:25 PM

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Path

Size

llvm/

trunk/

lib/

CodeGen/

SelectionDAG/

DAGCombiner.cpp

9 lines

test/

CodeGen/

AArch64/

addsub-constant-folding.ll

22 lines

X86/

addsub-constant-folding.ll

12 lines

Diff 202270

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llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

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llvm/trunk/test/CodeGen/AArch64/addsub-constant-folding.ll

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llvm/trunk/test/CodeGen/X86/addsub-constant-folding.ll

[DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-foldClosedPublicActions

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Diff 202270

llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

llvm/trunk/test/CodeGen/AArch64/addsub-constant-folding.ll

llvm/trunk/test/CodeGen/X86/addsub-constant-folding.ll

[DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold
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Revision Contents
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