The library call simplifier folds memcmp calls with all constant arguments
to a constant.  For example:

  memcmp("foo", "foo", 3) ->  0
  memcmp("hel", "foo", 3) ->  1
  memcmp("foo", "hel", 3) -> -1

The folding is implemented in terms of the system memcmp that LLVM gets
linked with.  It currently just blindly uses the value returned from
the system memcmp as the folded constant.

This patch normalizes the values returned from the system memcmp to
(-1, 0, 1) so that we get consistent results across multiple platforms.
The test cases were adjusted accordingly.

llvm-svn: 167726

This patch migrates the memset optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167689

This patch migrates the memmove optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167687

This patch migrates the memcpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167686

This patch migrates the memcmp optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167683

This patch migrates the strstr optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167682

In some cases the library call simplifier may need to replace instructions
other than the library call being simplified.  In those cases it may be
necessary for clients of the simplifier to override how the replacements
are actually done.  As such, a new overrideable method for replacing
instructions was added to LibCallSimplifier.

A new subclass of LibCallSimplifier is also defined which overrides
the instruction replacement method.  This is because the instruction
combiner defines its own replacement method which updates the worklist
when instructions are replaced.

llvm-svn: 167681

This patch migrates the strcspn optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167675

Several of the simplifiers migrated from the simplify-libcalls pass to
the instcombine pass were not correctly checking the target library
information to gate the simplifications.  This patch ensures that the
check is made.

llvm-svn: 167660

This patch migrates the strspn optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167568

is available.

llvm-svn: 167552

r165941: Resubmit the changes to llvm core to update the functions to
         support different pointer sizes on a per address space basis.

Despite this commit log, this change primarily changed stuff outside of
VMCore, and those changes do not carry any tests for correctness (or
even plausibility), and we have consistently found questionable or flat
out incorrect cases in these changes. Most of them are probably correct,
but we need to devise a system that makes it more clear when we have
handled the address space concerns correctly, and ideally each pass that
gets updated would receive an accompanying test case that exercises that
pass specificaly w.r.t. alternate address spaces.

However, from this commit, I have retained the new C API entry points.
Those were an orthogonal change that probably should have been split
apart, but they seem entirely good.

In several places the changes were very obvious cleanups with no actual
multiple address space code added; these I have not reverted when
I spotted them.

In a few other places there were merge conflicts due to a cleaner
solution being implemented later, often not using address spaces at all.
In those cases, I've preserved the new code which isn't address space
dependent.

This is part of my ongoing effort to clean out the partial address space
code which carries high risk and low test coverage, and not likely to be
finished before the 3.2 release looms closer. Duncan and I would both
like to see the above issues addressed before we return to these
changes.

llvm-svn: 167222

getIntPtrType support for multiple address spaces via a pointer type,
and also introduced a crasher bug in the constant folder reported in
PR14233.

These commits also contained several problems that should really be
addressed before they are re-committed. I have avoided reverting various
cleanups to the DataLayout APIs that are reasonable to have moving
forward in order to reduce the amount of churn, and minimize the number
of commits that were reverted. I've also manually updated merge
conflicts and manually arranged for the getIntPtrType function to stay
in DataLayout and to be defined in a plausible way after this revert.

Thanks to Duncan for working through this exact strategy with me, and
Nick Lewycky for tracking down the really annoying crasher this
triggered. (Test case to follow in its own commit.)

After discussing with Duncan extensively, and based on a note from
Micah, I'm going to continue to back out some more of the more
problematic patches in this series in order to ensure we go into the
LLVM 3.2 branch with a reasonable story here. I'll send a note to
llvmdev explaining what's going on and why.

Summary of reverted revisions:

r166634: Fix a compiler warning with an unused variable.
r166607: Add some cleanup to the DataLayout changes requested by
         Chandler.
r166596: Revert "Back out r166591, not sure why this made it through
         since I cancelled the command. Bleh, sorry about this!
r166591: Delete a directory that wasn't supposed to be checked in yet.
r166578: Add in support for getIntPtrType to get the pointer type based
         on the address space.
llvm-svn: 167221

- Use value handle tricks to communicate use replacements instead of forgetLoop, this is a lot faster.
- Move the "big hammer" out of the main loop so it's not called for every instruction.

This should recover most (if not all) compile time regressions introduced by this code.

llvm-svn: 167136

SimplifyCFG will have removed those cases for us.

llvm-svn: 167132

llvm-svn: 167130

 - Use 0 instead of NULL
 - Helper function for "dyn_cast, else lookup in the constant pool".

llvm-svn: 167121

This patch migrates the strto* optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167119

llvm-svn: 167117

By propagating the value for the switch condition, LLVM can now build
lookup tables for code such as:

  switch (x) {
    case 1: return 5;
    case 2: return 42;
    case 3: case 4: case 5:
      return x - 123;
    default:
      return 123;
  }

Given that x is known for each case, "x - 123" becomes a constant for
cases 3, 4, and 5.

llvm-svn: 167115

I'm not entirely happy with this solution, but I don't see a smarter way currently.
Fixes PR14214.

llvm-svn: 167112

This patch migrates the strpbrk optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167105

This patch migrates the strlen optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167103

This patch migrates the strncpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

llvm-svn: 167102

This patch migrates the stpcpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.  Note that the
__stpcpy_chk simplifications were migrated in a previous commit.

llvm-svn: 167083

r166198 migrated the strcpy optimization to instcombine.  The strcpy
simplifier that was migrated from Transforms/Scalar/SimplifyLibCalls.cpp
was also doing some __strcpy_chk simplifications.  Those fortified
simplifications were migrated as well, but introduced a bug in the
__stpcpy_chk simplifier in the process.  This happened because the
__strcpy_chk and __stpcpy_chk simplifiers were both mapped to StrCpyChkOpt
which was updated with simplifications that worked for __strcpy_chk, but
not __stpcpy_chk.

This patch fixes the problem by adding proper test coverage and creating a
new simplifier for __stpcpy_chk (instead of sharing one with __strcpy_chk).

llvm-svn: 167082

When the switch-to-lookup tables transform landed in SimplifyCFG, it
was pointed out that this could be inappropriate for some targets.
Since there was no way at the time for the pass to know anything about
the target, an awkward reverse-transform was added in CodeGenPrepare
that turned lookup tables back into switches for some targets.

This patch uses the new TargetTransformInfo to determine if a
switch should be transformed, and removes
CodeGenPrepare::ConvertLoadToSwitch.

llvm-svn: 167011

wrapper returns a vector of integers when passed a vector of pointers) by having
getIntPtrType itself return a vector of integers in this case.  Outside of this
wrapper, I didn't find anywhere in the codebase that was relying on the old
behaviour for vectors of pointers, so give this a whirl through the buildbots.

llvm-svn: 166939

This is currently true, but may change when DA grows more aggressive caching.
Without this setting it's impossible to use DA from a LoopPass because DA is a
function pass and cannot be properly scheduled in between LoopPasses. The
LoopManager reacts to this with an infinite loop which made this really annoying
to debug.

llvm-svn: 166788

The LoopSimplify bug is pretty harmless because the loop goes from unanalyzable
to analyzable but the LCSSA bug is very nasty. It only comes into play with a
specific order of the LoopPassManager worklist and can cause actual
miscompilations, when a SCEV refers to a value that has been replaced with PHI
node. SCEVExpander may then insert code into the wrong place, either violating
domination or randomly miscompiling stuff.

Comes with an extensive test case reduced from the test-suite with
bugpoint+SCEVValidator.

llvm-svn: 166787

The isValueEqualityComparison() guard at the top of SimplifySwitch()
only applies to some of the possible transformations.

The newer transformations work just fine on large switches, and the
check on predecessor count is nonsensical.

llvm-svn: 166710

llvm-svn: 166634

llvm-svn: 166607

This checkin also adds in some tests that utilize these paths and updates some of the
clients.

llvm-svn: 166578

llvm-svn: 166456

llvm-svn: 166454

deterministic, replace it with a DenseMap<std::pair<unsigned, unsigned>,
PHINode*> (we already have a map from BasicBlock to unsigned).

<rdar://problem/12541389>

llvm-svn: 166435

llvm-svn: 166340

llvm-svn: 166278

llvm-svn: 166264