Commit Graph

17 Commits

Author SHA1 Message Date
David Majnemer 1fea77c6fc [SimplifyCFG] Replace calls to null/undef with unreachable
Calling null is undefined behavior, a call to undef can be trivially
treated as a call to null.

llvm-svn: 273776
2016-06-25 07:37:27 +00:00
David Majnemer 7fddeccb8b Move the personality function from LandingPadInst to Function
The personality routine currently lives in the LandingPadInst.

This isn't desirable because:
- All LandingPadInsts in the same function must have the same
  personality routine.  This means that each LandingPadInst beyond the
  first has an operand which produces no additional information.

- There is ongoing work to introduce EH IR constructs other than
  LandingPadInst.  Moving the personality routine off of any one
  particular Instruction and onto the parent function seems a lot better
  than have N different places a personality function can sneak onto an
  exceptional function.

Differential Revision: http://reviews.llvm.org/D10429

llvm-svn: 239940
2015-06-17 20:52:32 +00:00
Duncan P. N. Exon Smith 49e6a70fe3 Verifier: Call verifyModule() from llc and opt
Change `llc` and `opt` to run `verifyModule()`.  This ensures that we
check the full module before `FunctionPass::doInitialization()` ever
gets called (I was getting crashes in `DwarfDebug` instead of verifier
failures when testing a WIP patch that checks operands of compile
units).  In `opt`, also move up debug-info-stripping so that it still
runs before verification.

There was a fair bit of broken code that was sitting in tree.
Interestingly, some were cases of a `select` that referred to itself in
`-instcombine` tests (apparently an intermediate result).  I split them
off to `*-noverify.ll` tests with RUN lines like this:

    opt < %s -S -disable-verify -instcombine | opt -S | FileCheck %s

This avoids verifying the input file (so we can get the broken code into
`-instcombine), but still verifies the output with a second call to
`opt` (to verify that `-instcombine` will clean it up like it should).

llvm-svn: 233432
2015-03-27 22:04:28 +00:00
Hans Wennborg 6800008f04 SimplifyCFG: don't remove unreachable default switch destinations
An unreachable default destination can be exploited by other optimizations and
allows for more efficient lowering. Both the SDag switch lowering and
LowerSwitch can exploit unreachable defaults.

Also make TurnSwitchRangeICmp handle switches with unreachable default.
This is kind of separate change, but it cannot be tested without the change
above, and I don't want to land the change above without this since that would
regress other tests.

Differential Revision: http://reviews.llvm.org/D6471

llvm-svn: 227125
2015-01-26 19:52:32 +00:00
Hans Wennborg 5bef5b522b Revert r223049, r223050 and r223051 while investigating test failures.
I didn't foresee affecting the Clang test suite :/

llvm-svn: 223054
2014-12-01 17:36:43 +00:00
Hans Wennborg 5a1e5c05d8 SimplifyCFG: don't remove unreachable default switch destinations
An unreachable default destination can be exploited by other optimizations, and
SDag lowering is now prepared to handle them efficiently.

For example, branches to the unreachable destination will be optimized away,
such as in the case of range checks for switch lookup tables.

On 64-bit Linux, this reduces the size of a clang bootstrap by 80 kB (and
Chromium by 30 kB).

llvm-svn: 223050
2014-12-01 17:08:35 +00:00
Marcello Maggioni 5bbe3df63f Switch to select optimization for two-case switches
This is the same optimization of r219233 with modifications to support PHIs with multiple incoming edges from the same block
and a test to check that this condition is handled.

llvm-svn: 219656
2014-10-14 01:58:26 +00:00
Joerg Sonnenberger 5ca10d0edb Revert r219223, it creates invalid PHI nodes.
llvm-svn: 219587
2014-10-12 17:16:04 +00:00
Arnold Schwaighofer d7d010eb2a SimplifyCFG: Don't convert phis into selects if we could remove undef behavior
instead

We used to transform this:

  define void @test6(i1 %cond, i8* %ptr) {
  entry:
    br i1 %cond, label %bb1, label %bb2

  bb1:
    br label %bb2

  bb2:
    %ptr.2 = phi i8* [ %ptr, %entry ], [ null, %bb1 ]
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

into this:

  define void @test6(i1 %cond, i8* %ptr) {
    %ptr.2 = select i1 %cond, i8* null, i8* %ptr
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

because the simplifycfg transformation into selects would happen to happen
before the simplifycfg transformation that removes unreachable control flow
(We have 'unreachable control flow' due to the store to null which is undefined
behavior).

The existing transformation that removes unreachable control flow in simplifycfg
is:

  /// If BB has an incoming value that will always trigger undefined behavior
  /// (eg. null pointer dereference), remove the branch leading here.
  static bool removeUndefIntroducingPredecessor(BasicBlock *BB)

Now we generate:

  define void @test6(i1 %cond, i8* %ptr) {
    store i8 2, i8* %ptr.2, align 8
    ret void
  }

I did not see any impact on the test-suite + externals.

rdar://18596215

llvm-svn: 219462
2014-10-10 01:27:02 +00:00
Marcello Maggioni 963bc87dbd Two case switch to select optimization
This optimization tries to convert switch instructions that are used to select a value with only 2 unique cases + default block
to a select or a couple of selects (depending if the default block is reachable or not).

The typical case this optimization wants to be able to optimize is this one:

Example:
switch (a) {
  case 10:                %0 = icmp eq i32 %a, 10
    return 10;            %1 = select i1 %0, i32 10, i32 4
  case 20:        ---->   %2 = icmp eq i32 %a, 20
    return 2;             %3 = select i1 %2, i32 2, i32 %1
  default:
    return 4;
}

It also sets the base for further optimizations that are planned and being reviewed.

llvm-svn: 219223
2014-10-07 18:16:44 +00:00
Stephen Lin c1c7a1309c Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change.
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186268
2013-07-14 01:42:54 +00:00
Eli Friedman c4414c6e92 PR9450: Make switch optimization in SimplifyCFG not dependent on the ordering
of pointers in an std::map.

llvm-svn: 127650
2011-03-15 02:23:35 +00:00
Dan Gohman 1880092722 Change tests from "opt %s" to "opt < %s" so that opt doesn't see the
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename.

llvm-svn: 81537
2009-09-11 18:01:28 +00:00
Dan Gohman 72a13d2476 Use opt -S instead of piping bitcode output through llvm-dis.
llvm-svn: 81257
2009-09-08 22:34:10 +00:00
Dan Gohman 9737a63ed8 Change these tests to feed the assembly files to opt directly, instead
of using llvm-as, now that opt supports this.

llvm-svn: 81226
2009-09-08 16:50:01 +00:00
Tanya Lattner baa370b37a Upgrade tests to not use llvm-upgrade.
llvm-svn: 48483
2008-03-18 03:45:45 +00:00
Reid Spencer 83b3d82672 Regression is gone, don't try to find it on clean target.
llvm-svn: 33296
2007-01-17 07:59:14 +00:00