[MergeICmps] Ignore clobbering instructions before the loads

This is another followup to D106591. Even if there is an
instruction that clobbers one of the loads, this doesn't matter if
it happens be

[MergeICmps] Ignore clobbering instructions before the loads

This is another followup to D106591. Even if there is an
instruction that clobbers one of the loads, this doesn't matter if
it happens before the loads. Those instructions aren't affected by
the transform at all.

The gep-references-bb.ll is modified to preserve the spirit of the
test, as the store to @g no longer impacts the transform.

Differential Revision: https://reviews.llvm.org/D108782

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[MergeICmps] Add test for call before first load (NFC)

If a clobbering call happens before all loads, that shouldn't
block the transform.

[MergeICmps] Allow sinking past non-load/store

This is a followup to D106591. MergeICmps currently only allows
sinking the loads past either instructions that don't write to
memory at all, or simple

[MergeICmps] Allow sinking past non-load/store

This is a followup to D106591. MergeICmps currently only allows
sinking the loads past either instructions that don't write to
memory at all, or simple loads/stores that don't modify the memory
the loads access.

The "simple loads/stores" part of this check doesn't seem necessary
to me -- AA isModRef() already accurately models any operation
that may clobber the memory. For example, in the adjusted test case
the transform is still fine if the call to @foo() isn't readonly,
but inaccessiblememonly -- in both cases, the call cannot modify
the loaded memory.

Differential Revision: https://reviews.llvm.org/D108517

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[MergeICmps] Relax sinking check

The check for sinking instructions past the load + cmp sequence
currently checks for side-effects, which includes writing to memory
and unwinding. However, I don't b

[MergeICmps] Relax sinking check

The check for sinking instructions past the load + cmp sequence
currently checks for side-effects, which includes writing to memory
and unwinding. However, I don't believe we care about sinking the
instructions past an unwind (as they don't have any side-effects
themselves).

Differential Revision: https://reviews.llvm.org/D106591

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[tests] Stablize tests for possible change in deref semantics

There's a potential change in dereferenceability attribute semantics in the nearish future. See llvm-dev thread "RFC: Decomposing deref

[tests] Stablize tests for possible change in deref semantics

There's a potential change in dereferenceability attribute semantics in the nearish future. See llvm-dev thread "RFC: Decomposing deref(N) into deref(N) + nofree" and D99100 for context.

This change simply adds appropriate attributes to tests to keep transform logic exercised under both old and new/proposed semantics. Note that for many of these cases, O3 would infer exactly these attributes on the test IR.

This change handles the idiomatic pattern of a dereferenceable object being passed to a call which can not free that memory. There's a couple other tests which need more one-off attention, they'll be handled in another change.

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Revert "[BuildLibCalls/SimplifyLibCalls] Fix attributes on created CallInst instructions."

This reverts commit 1eda5453f2dcc9a9a4b4578fe74163c529974503.

Causes https://crbug.com/1223647:
Incompati

Revert "[BuildLibCalls/SimplifyLibCalls] Fix attributes on created CallInst instructions."

This reverts commit 1eda5453f2dcc9a9a4b4578fe74163c529974503.

Causes https://crbug.com/1223647:
Incompatible argument and return types for 'returned' attribute
tail call void @llvm.memset.p0i8.i64(i8* noalias noundef returned writeonly align 1 dereferenceable(255) %arraydecay, i8 0, i64 255, i1 false), !dbg !985

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[BuildLibCalls/SimplifyLibCalls] Fix attributes on created CallInst instructions.

- When emitting libcalls, do not only pass the calling convention from the
function prototype but also the attrib

[BuildLibCalls/SimplifyLibCalls] Fix attributes on created CallInst instructions.

- When emitting libcalls, do not only pass the calling convention from the
function prototype but also the attributes.

- Do not pass attributes from e.g. libc memcpy to llvm.memcpy.

Review: Reid Kleckner, Eli Friedman, Arthur Eubanks

Differential Revision: https://reviews.llvm.org/D103992

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[MergeICmps] Preserve the dominator tree.

Summary: In preparation for D60318 .

Reviewers: gchatelet, efriedma

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://revi

[MergeICmps] Preserve the dominator tree.

Summary: In preparation for D60318 .

Reviewers: gchatelet, efriedma

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62068

llvm-svn: 361239

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Re-land r360859: "[MergeICmps] Simplify the code."

With a fix for PR41917: The predecessor list was changing under our feet.

- for (BasicBlock *Pred : predecessors(EntryBlock_)) {
+ while (!pred

Re-land r360859: "[MergeICmps] Simplify the code."

With a fix for PR41917: The predecessor list was changing under our feet.

- for (BasicBlock *Pred : predecessors(EntryBlock_)) {
+ while (!pred_empty(EntryBlock_)) {
+ BasicBlock* const Pred = *pred_begin(EntryBlock_);

llvm-svn: 361009

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Revert r360859: "Reland r360771 "[MergeICmps] Simplify the code.""

It caused PR41917.

llvm-svn: 360963

Reland r360771 "[MergeICmps] Simplify the code."

This revision does not seem to be the culprit.

llvm-svn: 360859

Revert r360771 "[MergeICmps] Simplify the code."

Breaks a bunch of builbdots.

llvm-svn: 360776

[MergeICmps] Simplify the code.

Instead of patching the original blocks, we now generate new blocks and
delete the old blocks. This results in simpler code with a less twisted
control flow (see the

[MergeICmps] Simplify the code.

Instead of patching the original blocks, we now generate new blocks and
delete the old blocks. This results in simpler code with a less twisted
control flow (see the change in `entry-block-shuffled.ll`).

This will make https://reviews.llvm.org/D60318 simpler by making it more
obvious where control flow created and deleted.

Reviewers: gchatelet

Subscribers: hiraditya, llvm-commits, spatel

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61736

llvm-svn: 360771

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[MergeICmps][NFC] Re-generate tests with update_test_checks.

And use a more compact name for the tested struct.

llvm-svn: 360319

Revert "Temporarily Revert "Add basic loop fusion pass.""

The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552

[MergeICmp] Split blocks that do other work.

Summary:
We do not try to move the instructions and split the block till we
know the blocks can be split, i.e. BCE-cmp-insts can be separated from
non-BC

[MergeICmp] Split blocks that do other work.

Summary:
We do not try to move the instructions and split the block till we
know the blocks can be split, i.e. BCE-cmp-insts can be separated from
non-BCE-cmp-insts.

Reviewers: davide, courbet

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D44443

llvm-svn: 329564

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