Reuse the existing KnownBits multiplication code to handle what is effectively a ISD::UMUL_LOHI varient

With this change, for `#include <ar.h>`, `clang --target=aarch64-linux-gnu`
will read `/usr/lib/gcc/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/include/ar.h`
(on Debian gcc->gcc-cross)
instead of `/usr/include/ar.h`. Some glibc headers (e.g. gnu/stubs.h) are different across architectures.

Seem unnecessary to diverge from GCC here.
Beside, lib/../$OSLibDir can be considered closer to the GCC
installation then the system root. The comment should not apply.

Removing the hack actually improves our compatibility with gcc -mx32.

If clang is installed in the system, the other -L suffice;
otherwise $ccc_install_dir/../lib below suffices.

After path resolution, it duplicates a subsequent -L entry. The entry below
(lib/gcc/$triple/$version/../../../../$OSLibDir) usually does not exist (e.g.
Arch Linux; Debian cross gcc). When it exists, it typically just has ld.so (e.g.
Debian native gcc) which cannot cause collision. Removing the -L (similar to
reordering it) is therefore justified.

[RISCV] Add test case to show a case where (mul (and X, 0xffffffff), (and Y, 0xffffffff)) optimization does not improve code.

If the mul add two users, one of which was a sext.w, the mul
would also be selected to a MULW before our pattern runs. This
causes the ANDs to now be used by the already selected MULW and
the mul we still need to select. They are unneeded on the MULW
since MULW only reads the lower bits. So they get selected to
SLLI+SRLI for the MULW use. The use for the
(mul (and X, 0xffffffff), (and Y, 0xffffffff)) manages to reuse
the SLLI.

The end result is increased register pressure and no improvement
to how soon we can start the MULW.

This reapplies b5d9a3c9 / https://reviews.llvm.org/D98609 with a one line fix in
processExistingConstants to skip() when erasing a constant we've already seen.

Original commit message:

 1) Change the canonicalizer to walk the function in top-down order instead of
    bottom-up order.  This composes well with the "top down" nature of constant
    folding and simplification, reducing iterations and re-evaluation of ops in
    simple cases.
 2) Explicitly enter existing constants into the OperationFolder table before
    canonicalizing.  Previously we would "constant fold" them and rematerialize
    them, wastefully recreating a bunch fo constants, which lead to pointless
    memory traffic.

Both changes together provide a 33% speedup for canonicalize on some mid-size
CIRCT examples.

One artifact of this change is that the constants generated in normal pattern
application get inserted at the top of the function as the patterns are applied.
Because of this, we get "inverted" constants more often, which is an aethetic
change to the IR but does permute some testcases.

Differential Revision: https://reviews.llvm.org/D99006

Causing build errors on the Windows Buildbots.

This reverts commit 5155dff2.

Missed in 07ed62b7.

This optimization is trying to save SRLI instructions needed to
implement the ANDs. If we have zext.w we won't save anything.
Because we don't check that the multiply is the only user of the
AND we might even increase instruction count.

Some of the patterns end up with 32 to 64 bit zero extends on RV64
which can be handled by zext.w.

This patterns computes the full 64 bit product of a 32x32 unsigned
multiply. This requires a two pairs of SLLI+SRLI to zero the
upper 32 bits of the inputs.

We can do better than this by using two SLLI to move the lower
bits to the upper bits then use MULHU to compute the product. This
is the high half of a full 64x64 product. Since we put 32 0s in the lower
bits of the inputs we know the 128-bit product will have zeros in the
lower 64 bits. So the upper 64 bits, which MULHU computes, will contain
the original 64 bit product we were after.

The same trick would work for (mul (sext_inreg X, i32), (sext_inreg Y, i32))
using MULHS, but sext_inreg is sext.w which is already one instruction so we
wouldn't save anything.

Differential Revision: https://reviews.llvm.org/D99026

This is a similarity visualization tool that accepts a Module and
passes it to the IRSimilarityIdentifier.  The resulting SimilarityGroups
are output in a JSON file.

Tests are found in test/tools/llvm-sim and check for the file not found,
a bad module, and that the JSON is created correctly.

Reviewers: paquette, jroelofs, MaskRay

Recommit of: 15645d04 to fix linking
errors.

Differential Revision: https://reviews.llvm.org/D86974

BUILD_SHARED_LIBS build llvm component as shared library,
which can reduce the size a lot.

Normally, the binary use ORIGIN../lib to load component libraries,
unfortunatly, ORIGIN is not supported by AIX ld.

We hardcoded the build lib and install lib path in rpath for now
to enable BUILD_SHARED_LIBS build.

Understand that this is not perfect solution,
we can update this when we find better solution.

Reviewed By: hubert.reinterpretcast

Differential Revision: https://reviews.llvm.org/D98901

This makes the settings available for use in other passes by housing
them within the Support lib, but NFC otherwise.

See D98898 for the proposed usage in SimplifyCFG
(where this change was originally included).

Differential Revision: https://reviews.llvm.org/D98945

Differential Revision: https://reviews.llvm.org/D98827

There were not properly checked before `[TableGen] Improve handling of template arguments`.

This reverts commit 243333ef.

Also:

- Fix a bug that crept in when fixing a buildbot failure in
https://github.com/llvm/llvm-project/commit/f7be9db6220cb39f0eaa12d2af3abedf0d86c303
- Use mlsize_t for cstr_to_string as that is what
caml_alloc_string specifies.

Differential Revision: https://reviews.llvm.org/D98851

As fallout from from the record-and-reorder work, people asked that the
summary output be sorted to aid diffing.

This reverts commit bdf39e6b.

The change is failing on Fedora 33 (x86-64).

Don't emit a warning if the `continue` appears in a switch context as changing it to `break` will break out of the switch rather than a do loop containing the switch.
Fixes https://llvm.org/PR49492.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D98338

* Fold SelectOp when both true and false args are same SSA value
* Fold some cmp + select patterns

Differential Revision: https://reviews.llvm.org/D98576

Now that intrinsic name mangling can cope with unnamed types, the custom name mangling in PredicateInfo (introduced by D49126) can be removed.
(See D91250, D48541)

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D91661

The BB we initialized the ldtilecfg is special. We don't need to check
if its predecessor BBs need to insert ldtilecfg for calls.

We reused the flag HasCallBeforeAMX, so that the predecessors won't be
added to CfgNeedInsert.

This case happens only when the entry BB is in a loop. We need to hoist
the first tile config point out of the loop in future.

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D98845

* Do we need a threshold on maximum number of Yeild arguments processed (maximum number of SelectOp's to be generated)?
* Had to modify some old IfOp tests to not get optimized by this pattern

Differential Revision: https://reviews.llvm.org/D98592

https://reviews.llvm.org/D85534#2636321

Title: Remove a redundant parameter in clang/unittests/AST/CMakeLists.txt Reviewed by: MaskRay Differential Revision: https://reviews.llvm.org/D98922

It has a very broken gcc installation path (usr/lib/i386-linux-gnu/gcc/i686-linux-gnu).

This is used by hurd.c (usr/lib/gcc/i386-gnu/4.6.0) but we can leverage
the existing alias triple detection.

Adjusted some whitespaces.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D98975