[InstCombine] Fix APInt ctor assertion

The (extended) bit width might not fit into the (non-extended)
type, resulting in an incorrect truncation of the compared value.

Fix this by using m_SpecificI

[InstCombine] Fix APInt ctor assertion

The (extended) bit width might not fit into the (non-extended)
type, resulting in an incorrect truncation of the compared value.

Fix this by using m_SpecificInt(), which is both simpler and
handles this correctly.

Fixes the assertion failure reported in:
https://github.com/llvm/llvm-project/pull/114539#issuecomment-2485799395

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[InstCombine] Infer shift flags with unknown shamt (#72535)

Alive2: https://alive2.llvm.org/ce/z/82Wr3q

Related patch:
https://github.com/llvm/llvm-project/commit/2dd52b4527667837cc525aa48435ab5

[InstCombine] Infer shift flags with unknown shamt (#72535)

Alive2: https://alive2.llvm.org/ce/z/82Wr3q

Related patch:
https://github.com/llvm/llvm-project/commit/2dd52b4527667837cc525aa48435ab5cbfa30a0b

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[InstCombine] add nuw to any (1<<x)

https://alive2.llvm.org/ce/z/9EjDKE

This was mentioned as a missing fold in D139598.

It can unlock follow-on folds in some cases.
This verifies one of the chang

[InstCombine] add nuw to any (1<<x)

https://alive2.llvm.org/ce/z/9EjDKE

This was mentioned as a missing fold in D139598.

It can unlock follow-on folds in some cases.
This verifies one of the changed tests:
https://alive2.llvm.org/ce/z/B_btDM

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[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://r

[test] Use -passes=instcombine instead of -instcombine in lots of tests. NFC

Another step moving away from the deprecated syntax of specifying
pass pipeline in opt.

Differential Revision: https://reviews.llvm.org/D119081

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[InstCombine] use redirect of input file in regression tests; NFC

This is a repeat of 1880092722 from 2009. We should have less risk
of hitting bugs at this point because we auto-generate positive C

[InstCombine] use redirect of input file in regression tests; NFC

This is a repeat of 1880092722 from 2009. We should have less risk
of hitting bugs at this point because we auto-generate positive CHECK
lines only, but this makes things consistent.

Copying the original commit msg:
"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."

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[InstCombine] conditional sign-extend of high-bit-extract: 'or' pattern.

In this pattern, all the "magic" bits that we'd `add` are all
high sign bits, and in the value we'd be adding to they are all

[InstCombine] conditional sign-extend of high-bit-extract: 'or' pattern.

In this pattern, all the "magic" bits that we'd `add` are all
high sign bits, and in the value we'd be adding to they are all unset,
not unexpectedly, so we can have an `or` there:
https://rise4fun.com/Alive/ups

It is possible that `haveNoCommonBitsSet()` should be taught about this
pattern so that we never have an `add` variant, but the reasoning would
need to be recursive (because of that `select`), so i'm not really sure
that would be worth it just yet.

llvm-svn: 375378

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[NFC][InstCombine] conditional sign-extend of high-bit-extract: 'and' pat. can be 'or' pattern.

In this pattern, all the "magic" bits that we'd add are all
high sign bits, and in the value we'd be a

[NFC][InstCombine] conditional sign-extend of high-bit-extract: 'and' pat. can be 'or' pattern.

In this pattern, all the "magic" bits that we'd add are all
high sign bits, and in the value we'd be adding to they are all unset,
not unexpectedly, so we can have an `or` there:
https://rise4fun.com/Alive/ups

llvm-svn: 375377

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[InstCombine] Fold conditional sign-extend of high-bit-extract into high-bit-extract-with-signext (PR42389)

This can come up in Bit Stream abstractions.

The pattern looks big/scary, but it can't be

[InstCombine] Fold conditional sign-extend of high-bit-extract into high-bit-extract-with-signext (PR42389)

This can come up in Bit Stream abstractions.

The pattern looks big/scary, but it can't be simplified any further.
It only is so simple because a number of my preparatory folds had
happened already (shift amount reassociation / shift amount
reassociation in bit test, sign bit test detection).

Highlights:
* There are two main flavors: https://rise4fun.com/Alive/zWi
The difference is add vs. sub, and left-shift of -1 vs. 1
* Since we only change the shift opcode,
we can preserve the exact-ness: https://rise4fun.com/Alive/4u4
* There can be truncation after high-bit-extraction:
https://rise4fun.com/Alive/slHc1 (the main pattern i'm after!)
Which means that we need to ignore zext of shift amounts and of NBits.
* The sign-extending magic can be extended itself (in add pattern
via sext, in sub pattern via zext. not the other way around!)
https://rise4fun.com/Alive/NhG
(or those sext/zext can be sinked into `select`!)
Which again means we should pay attention when matching NBits.
* We can have both truncation of extraction and widening of magic:
https://rise4fun.com/Alive/XTw
In other words, i don't believe we need to have any checks on
bitwidths of any of these constructs.

This is worsened in general by the fact that we may have `sext` instead
of `zext` for shift amounts, and we don't yet canonicalize to `zext`,
although we should. I have not done anything about that here.

Also, we really should have something to weed out `sub` like these,
by folding them into `add` variant.

https://bugs.llvm.org/show_bug.cgi?id=42389

llvm-svn: 373964

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[InstCombine][NFC] Tests for "conditional sign-extend of high-bit-extract" pattern (PR42389)

https://bugs.llvm.org/show_bug.cgi?id=42389

llvm-svn: 373963