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llvm-project/llvm/test/Transforms/IndVarSimplify
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Sanjoy Das 6f062c8c2a [IndVars] Try to use existing values in RewriteLoopExitValues. 
Summary:
In RewriteLoopExitValues, before expanding out an SCEV expression using
SCEVExpander, try to see if an existing LLVM IR expression already
computes the value we're interested in.  If so use that existing
expression.

Apart from reducing IndVars' reliance on the rest of the compilation
pipeline, this also prevents IndVars from concluding some expressions as
"high cost" when they're not.  For instance,
`InductiveRangeCheckElimination` often emits code of the following form:

```
len = umin(len_A, len_B)

loop:
  ...
  if (i++ < len)
    goto loop

outside_loop:
    use(i)
```

`SCEVExpander` refuses to rewrite the use of `i` in `outside_loop`,
since it thinks the value of `i` on loop exit, `len`, is a high cost
expansion since it contains an `umax` in it.  With this change,
`IndVars` can see that it can re-use `len` instead of creating a new
expression to compute `umin(len_A, len_B)`.

I considered putting this cleverness in `SCEVExpander`, but I was
worried that it may then have a deterimental effect on other passes
that use it.  So I decided it was better to just do this in the one
place where it seems like an obviously good idea, with the intent of
generalizing later if needed.

Reviewers: atrick, reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10782

llvm-svn: 241838
 		2015-07-09 18:46:12 +00:00
..
NVPTX [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
2002-09-09-PointerIndVar.ll
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2003-04-16-ExprAnalysis.ll
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2003-09-23-NotAtTop.ll
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2003-12-10-RemoveInstrCrash.ll
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2003-12-15-Crash.ll
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2004-03-10-PHIInsertionBug.ll
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2004-04-05-InvokeCastCrash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2004-04-07-ScalarEvolutionCrash.ll
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2005-02-11-InvokeCrash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2005-02-17-TruncateExprCrash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
2005-02-26-ExitValueCompute.ll
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2005-06-15-InstMoveCrash.ll
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2005-11-18-Crash.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
2006-03-31-NegativeStride.ll
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2006-06-16-Indvar-LCSSA-Crash.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2006-09-20-LFTR-Crash.ll
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2006-12-10-BitCast.ll
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2007-01-06-TripCount.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2007-06-06-DeleteDanglesPtr.ll
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2007-11-23-BitcastCrash.ll
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2008-06-15-SCEVExpanderBug.ll
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2008-09-02-IVType.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
2008-10-03-CouldNotCompute.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2008-11-25-APFloatAssert.ll
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2009-04-14-shorten_iv_vars.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2009-04-15-shorten-iv-vars-2.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2009-04-22-IndvarCrash.ll
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2009-04-27-Floating.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
2009-05-24-useafterfree.ll
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2011-09-10-widen-nsw.ll This patch teaches IndVarSimplify to add nuw and nsw to certain kinds 2015-01-06 19:02:56 +00:00
2011-09-19-vectoriv.ll
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2011-09-27-hoistsext.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2011-10-27-lftrnull.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
2011-11-01-lftrptr.ll Verifier: Call verifyModule() from llc and opt 2015-03-27 22:04:28 +00:00
2011-11-15-multiexit.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
2011-11-17-selfphi.ll
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2012-07-17-lftr-undef.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
2012-10-19-congruent-constant.ll
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2014-06-21-congruent-constant.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
ada-loops.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
ashr-tripcount.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
avoid-i0.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
backedge-on-min-max.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
casted-argument.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
crash.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
dangling-use.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
divide-pointer.ll
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dont-recompute.ll
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elim-extend.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
eliminate-comparison.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
eliminate-max.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
eliminate-rem.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
exit_value_test2.ll Enable exitValue rewrite only when the cost of expansion is low. 2015-05-28 21:49:07 +00:00
exit_value_test3.ll Enable exitValue rewrite only when the cost of expansion is low. 2015-05-28 21:49:07 +00:00
exit_value_tests.ll
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floating-point-iv.ll
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indirectbr.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
interesting-invoke-use.ll Move the personality function from LandingPadInst to Function 2015-06-17 20:52:32 +00:00
iterationCount_zext_or_trunc.ll
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iv-fold.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
iv-sext.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
iv-widen.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
iv-zext.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
lcssa-preservation.ll Enable exitValue rewrite only when the cost of expansion is low. 2015-05-28 21:49:07 +00:00
lftr-address-space-pointers.ll Revert some changes that were made to fix PR20680. 2015-03-02 21:41:07 +00:00
lftr-extend-const.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
lftr-other-uses.ll
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lftr-promote.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
lftr-reuse.ll Revert some changes that were made to fix PR20680. 2015-03-02 21:41:07 +00:00
lftr-udiv-tripcount.ll [SCEV] Strengthen SCEVExpander::isHighCostExpansion. 2015-04-14 03:20:32 +00:00
lftr-zext.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
lftr_simple.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
loop_evaluate7.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
loop_evaluate8.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
loop_evaluate9.ll [opaque pointer type] Add textual IR support for explicit type parameter to gep operator 2015-03-13 18:20:45 +00:00
loop_evaluate10.ll
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loop_evaluate11.ll
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loop_evaluate_1.ll
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loop_evaluate_2.ll
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loop_evaluate_3.ll
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loop_evaluate_4.ll
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loop_evaluate_5.ll
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loop_evaluate_6.ll
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lrev-existing-umin.ll [IndVars] Try to use existing values in RewriteLoopExitValues. 2015-07-09 18:46:12 +00:00
masked-iv.ll [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction 2015-02-27 19:29:02 +00:00
no-iv-rewrite.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
overflowcheck.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
phi-uses-value-multiple-times.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
polynomial-expand.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
pr18223.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
pr20680.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
pr22222.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
preserve-signed-wrap.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
promote-iv-to-eliminate-casts.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
sharpen-range.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
shrunk-constant.ll
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signed-trip-count.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
single-element-range.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
sink-alloca.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
sink-trapping.ll
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strengthen-overflow.ll Fix PR22222 2015-01-15 01:46:09 +00:00
tripcount_compute.ll
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tripcount_infinite.ll
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udiv-invariant-but-traps.ll
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udiv.ll [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction 2015-04-16 23:24:18 +00:00
uglygep.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
ult-sub-to-eq.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
use-range-metadata.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
variable-stride-ivs-0.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
variable-stride-ivs-1.ll
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verify-scev.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00
widen-loop-comp.ll Make DataLayout Non-Optional in the Module 2015-03-04 18:43:29 +00:00
widen-nsw.ll [opaque pointer type] Add textual IR support for explicit type parameter to load instruction 2015-02-27 21:17:42 +00:00