This has the side effect of fixing the FIXME for when
use-constant-int-for-fixed-length-splat becomes the default.

Another step towards getting rid of dependencies to the legacy
pass manager.

Primary change here is to just do -passes=foo instead of -foo in
simple situations (when running a single transform pass). But also
updated a few test running multiple passes.

Also removed some "duplicated" RUN lines in a few tests that where
using both -foo and -passes=foo syntax. No need to do the same kind
of testing twice.

In analyzing issue #56483, it was noticed that running `opt` with
`-reassociate` was missing some minor optimizations. For example,
there were cases where the running `opt` on IR with floating-point
instructions that have the `fast` flags applied, sometimes resulted in
less efficient code than the input IR (things like dead instructions
left behind, and missed reassociations). These were sometimes noted
in the test-files with TODOs, to investigate further. This commit
fixes some of these problems, removing some TODOs in the process.

FTR, I refer to these as "minor" missed optimizations, because when
running a full clang/llvm compilation, these inefficiencies are not
happening, as other passes clean that residue up. Regardless, having
cleaner IR produced by `opt`, makes assessing the quality of fixes done
in `opt` easier.

This is an extension of a transform that tries to produce positive floating-point
constants to improve canonicalization (and hopefully lead to more reassociation
and CSE).

The original patches were:
D4904
D5363 (rL221721)

But as the test diffs show, these were limited to basic patterns by walking from
an instruction to its single user rather than recursively moving up the def-use
sequence. No fast-math is required here because we're only rearranging implicit
FP negations in intermediate ops.

A motivating bug is:
https://bugs.llvm.org/show_bug.cgi?id=32939

Differential Revision: https://reviews.llvm.org/D65954

llvm-svn: 368512

llvm-svn: 364232

The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552

As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546

This algorithm (explained more in the source code) takes into account
global redundancies by building a "pair map" to find common subexprs.

The primary motivation of this is to handle situations like

foo = (a * b) * c
bar = (a * d) * c

where we currently don't identify that "a * c" is redundant.

Accordingly, it prioritizes the emission of a * c so that CSE
can remove the redundant calculation later.

Does not change the actual reassociation algorithm -- only the
order in which the reassociated operand chain is reconstructed.

Gives ~1.5% floating point math instruction count reduction on
a large offline suite of graphics shaders.

llvm-svn: 320515

llvm-svn: 318076