In the existing logic, for a given alloca, as long as its pointer value is stored into another location, it's considered as escaped.
This is a bit too conservative. Specifically, in non-optimized build mode, it's often to have patterns of code that first store an alloca somewhere and then load it right away.
These used should be handled without conservatively marking them escaped.
This patch tracks how the memory location where an alloca pointer is stored into is being used. As long as we only try to load from that location and nothing else, we can still
consider the original alloca not escaping and keep it on the stack instead of putting it on the frame.
Differential Revision: https://reviews.llvm.org/D91305
No longer rely on an external tool to build the llvm component layout.
Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.
These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.
Differential Revision: https://reviews.llvm.org/D90848
In the existing logic, for a given alloca, as long as its pointer value is stored into another location, it's considered as escaped.
This is a bit too conservative. Specifically, in non-optimized build mode, it's often to have patterns of code that first store an alloca somewhere and then load it right away.
These used should be handled without conservatively marking them escaped.
This patch tracks how the memory location where an alloca pointer is stored into is being used. As long as we only try to load from that location and nothing else, we can still
consider the original alloca not escaping and keep it on the stack instead of putting it on the frame.
Differential Revision: https://reviews.llvm.org/D91305
We need to be able to call function pointers. Inline the dispatch
function.
Also inline the context projection function.
Transfer debug locations from the suspend point to the inlined functions.
Use the function argument index instead of the function argument in
coro.id.async. This solves any spurious use issues.
Coerce the arguments of the tail call function at a suspend point. The LLVM
optimizer seems to drop casts leading to a vararg intrinsic.
rdar://70097093
Differential Revision: https://reviews.llvm.org/D91098
Tracking local variables across suspend points is still somewhat incomplete.
Consider this coroutine snippet:
```
resumable foo() {
int x[10] = {};
int a = 3;
co_await std::experimental::suspend_always();
a++;
x[0] = 1;
a += 2;
x[1] = 2;
a += 3;
x[2] = 3;
}
```
Can't manage to print `a` or `x` if they turn out to be allocas during
CoroSplit (which happens if you build this code with `-O0` prior to this
commit):
```
* thread #1, queue = 'com.apple.main-thread', stop reason = step over
frame #0: 0x0000000100003729 main-noprint`foo() at main-noprint.cpp:43:5
40 co_await std::experimental::suspend_always();
41 a++;
42 x[0] = 1;
-> 43 a += 2;
44 x[1] = 2;
45 a += 3;
46 x[2] = 3;
(lldb) p x
error: <user expression 21>:1:1: use of undeclared identifier 'x'
x
^
```
The generated IR contains a `llvm.dbg.declare` for `x` in it's initialization
basic block. After CoroSplit, the `llvm.dbg.declare` might not dominate all of
`x` uses and we lose debugging quality.
Add `llvm.dbg.value`s to all relevant basic blocks such that if later
transformations break the dominance the reliable debug info is already in
place. For instance, this BB:
```
await.ready:
...
%arrayidx = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 0, !dbg !760
...
%arrayidx19 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 1, !dbg !763
...
%arrayidx21 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 2, !dbg !766
```
becomes:
```
await.ready:
...
call void @llvm.dbg.value(metadata [10 x i32]* %x.reload.addr, metadata !751, metadata !DIExpression()), !dbg !753
...
%arrayidx = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 0, !dbg !760
...
%arrayidx19 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 1, !dbg !763
...
%arrayidx21 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 2, !dbg !766
```
Differential Revision: https://reviews.llvm.org/D90772
Prior to D89768, any alloca that's used after suspension points will be put on to the coroutine frame, and hence they will always be reloaded in the resume function.
However D89768 introduced a more precise way to determine whether an alloca should live on the frame. Allocas that are only used within one suspension region (hence does not need to live across suspension points) will not be put on the frame. They will remain local to the resume function.
When creating the new entry for the .resume function, the existing logic only moved all the allocas from the old entry to the new entry. This covers every alloca from the old entry. However allocas that's defined afer coro.begin are put into a separate basic block during CoroSplit (the PostSpill basic block). We need to make sure these allocas are moved to the new entry as well if they are used.
This patch walks through all allocas, and check if they are still used but are not reachable from the new entry, if so, we move them to the new entry.
Differential Revision: https://reviews.llvm.org/D90977
The `llvm.coro.suspend.async` intrinsic takes a function pointer as its
argument that describes how-to restore the current continuation's
context from the context argument of the continuation function. Before
we assumed that the current context can be restored by loading from the
context arguments first pointer field (`first_arg->caller_context`).
This allows for defining suspension points that reuse the current
context for example.
Also:
llvm.coro.id.async lowering: Add llvm.coro.preprare.async intrinsic
Blocks inlining until after the async coroutine was split.
Also, change the async function pointer's context size position
struct async_function_pointer {
uint32_t relative_function_pointer_to_async_impl;
uint32_t context_size;
}
And make the position of the `async context` argument configurable. The
position is specified by the `llvm.coro.id.async` intrinsic.
rdar://70097093
Differential Revision: https://reviews.llvm.org/D90783
This patch adds the `async` lowering of coroutines.
This will be used by the Swift frontend to lower async functions. In
contrast to the `retcon` lowering the frontend needs to be in control
over control-flow at suspend points as execution might be suspended at
these points.
This is very much work in progress and the implementation will change as
it evolves with the frontend. As such the documentation is lacking
detail as some of it might change.
rdar://70097093
Reapply with fix for memory sanitizer failure and sphinx failure.
Differential Revision: https://reviews.llvm.org/D90612
This patch adds the `async` lowering of coroutines.
This will be used by the Swift frontend to lower async functions. In
contrast to the `retcon` lowering the frontend needs to be in control
over control-flow at suspend points as execution might be suspended at
these points.
This is very much work in progress and the implementation will change as
it evolves with the frontend. As such the documentation is lacking
detail as some of it might change.
rdar://70097093
Differential Revision: https://reviews.llvm.org/D90612
The existing logic in determining whether an alloca should live on the frame only looks explicit def-use relationships. However a value defined by an alloca may be implicitly needed across suspension points, either because an alias has across-suspension-point def-use relationship, or escaped by store/call/memory intrinsics. To properly handle all these cases, we have to properly visit the alloca pointer up-front. Thie patch extends the exisiting alloca use visitor to determine whether an alloca should live on the frame.
Differential Revision: https://reviews.llvm.org/D89768
This patch is a refactoring of how we process spills and allocas during CoroSplit.
In the previous implementation, everything that needs to go to the heap is put into Spills, including all the values defined by allocas.
And the way to identify a Spill, is to check whether there exists a use-def relationship that crosses suspension points.
This approach is fundamentally confusing, and unfortunately, incorrect.
First of all, allocas are always process differently than spills, hence it's quite confusing to put them together. It's a much cleaner to separate them and process them separately.
Doing so simplify lots of code and makes the logic more clear and easier to reason about.
Secondly, use-def relationship is insufficient to decide whether a value defined by AllocaInst needs to go to the heap.
There are many cases where a value defined by AllocaInst can implicitly be used across suspension points without a direct use-def relationship.
For example, you can store the address of an alloca into the heap, and load that address after suspension. Or you can escape the address into an object through a function call.
Or you can have a PHINode that takes two allocas, and this PHINode is used across suspension point (when this happens, the existing implementation will spill the PHINode, a.k.a a stack adddress to the heap!).
All these issues suggest that we need to separate spill and alloca in order to properly implement this.
This patch does not yet fix these bugs, however it sets up the code in a better shape so that we can start fixing them in the next patch.
The core idea of this patch is to add a new struct called FrameDataInfo, which contains all Spills, all Allocas, and a map from each definition to its layout index in the frame (FieldIndexMap).
Spills and Allocas are identified, stored and processed independently. When they are initially added to the frame, we record their field index through FieldIndexMap. When the frame layout is finalized, we update each index into their final layout index.
In doing so, I also cleaned up a few things and also discovered a few other bugs.
Cleanups:
1. Found out that PromiseFieldId is not used, delete it.
2. Previously, SpillInfo is a vector, which is strange because every def can have multiple users. This patch cleans it up by turning it into a map from def to users.
3. Previously, a frame Field struct contains a list of Spills that field corresponds to. This isn't necessary since we only need the layout index for each given definition. This patch removes that list. Instead, we connect each field and definition using the FieldIndexMap.
4. All the loops that process Spills are simplified now because we use a map instead of a vector.
Bugs:
It seems that we are only keeping llvm.dbg.declare intrinsics in the .resume part of the function. The ramp function will no longer has it. This means we are dropping some debug information in the ramp function.
The next step is to start fixing the bugs where the implementation fails to identify some allocas that should live on the frame.
Differential Revision: https://reviews.llvm.org/D88872
bug 45566 shows the process of building coroutine frame won't consider
that the lifetimes of different local variables are not overlapped,
which means the compiler could generates smaller frame.
This patch calculate the lifetime range of each alloca by StackLifetime
class. Then the patch build non-overlapped sets for allocas whose
lifetime ranges are not overlapped. We use the largest type in a
non-overlapped set as the field type in the frame. In insertSpills
process, if we find the type of field is not the same with the alloca,
we cast the pointer to the field type to the pointer to the alloca type.
Since the lifetime range of alloca in one non-overlapped set is not
overlapped with each other, it should be ok to reuse the storage space
in the frame.
Test plan: check-llvm, check-clang, cppcoro, folly
Reviewers: junparser, lxfind, modocache
Differential Revision: https://reviews.llvm.org/D87596
Issue Details:
In order to support coroutine splitting, any multi-value PHI node in a coroutine is split into multiple blocks with single-value PHI Nodes, which then allows a subsequent transform to generate `reload` instructions as required (i.e., to reload the value if required if the coroutine has been resumed). This causes issues with EH pads (`catchswitch` and `catchpad`) as all pads within a `catchswitch` must have the same unwind destination, but the coroutine splitting logic may modify them to each have a unique unwind destination if there is a PHI node in the unwind `cleanuppad` that is set from values in the `catchswitch` and `cleanuppad` blocks.
Fix Details:
During splitting, if such a PHI node is detected, then create a "dispatcher" `cleanuppad` as well as the blocks with single-value PHI Nodes: thus the "dispatcher" is the unwind destination and it will detect which predecessor called it and then branch to the appropriate single-value PHI node block, which will then branch back to the original `cleanuppad` block.
Reviewed By: GorNishanov, lxfind
Differential Revision: https://reviews.llvm.org/D88059
This seems to fit the CGSCC updates model better than calling
addNewFunctionInto{Ref,}SCC() on newly created/outlined functions.
Now addNewFunctionInto{Ref,}SCC() are no longer necessary.
However, this doesn't work on newly outlined functions that aren't
referenced by the original function. e.g. if a() was outlined into b()
and c(), but c() is only referenced by b() and not by a(), this will
trigger an assert.
This also fixes an issue I was seeing with newly created functions not
having passes run on them.
Ran check-llvm with expensive checks.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D87798
When a spill definition is before CoroBegin, we cannot spill it to the frame immediately after the definition. We have to spill it after the frame is ready.
The current implementation handles it properly for any other kinds of instructions except for PhINode and InvokeInst, which could also be defined before CoroBegin.
This patch fixes it by moving the CoroBegin dominance check earlier, so that it covers all cases.
Added a test.
Differential Revision: https://reviews.llvm.org/D87810
D66230 attempted to fix a problem where when there are allocas used before CoroBegin.
It keeps allocas and their uses stay in put if there are no escapse/changes to the data before CoroBegin.
Unfortunately that's incorrect.
Consider this code:
%var = alloca i32
%1 = getelementptr .. %var; stays put
%f = call i8* @llvm.coro.begin
store ... %1
After this fix, %1 will now stay put, however if a store happens after coro.begin and hence modifies the content, this change will not be reflected in the coroutine frame (and will eventually be DCEed).
To generalize the problem, if any alias ptr is created before coro.begin for an Alloca and that alias ptr is latter written into after coro.begin, it will lead to incorrect behavior.
There are also a few other minor issues, such as incorrect dominate condition check in the ptr visitor, unhandled memory intrinsics and etc.
Ths patch attempts to fix some of these issue, and make it more robust to deal with aliases.
While visiting through the alloca pointer, we also keep track of all aliases created that will be used after CoroBegin. We track the offset of each alias, and then reacreate these aliases after CoroBegin using these offset.
It's worth noting that this is not perfect and there will still be cases we cannot handle. I think it's impractical to handle all cases given the current design.
This patch makes it more robust and should be a pure win.
In the meantime, we need to think about what how to completely elimiante these issues, likely through the route as @rjmccall mentioned in D66230.
Differential Revision: https://reviews.llvm.org/D86859
This reverts commit 2e43acfed89b1903de473f682c65878bdebc395a.
LLVMCoroutines (the library which contains Coroutines.h) depends on LLVMipo (the
library which contains SampleProfile.cpp). It is inappropriate for
SampleProfile.cpp to depent on Coroutines.h (circular dependency).
The test inverted dependencies as well:
llvm/test/Transforms/Coroutines/coro-inline.ll uses -sample-profile.
summary:
When callee coroutine function is inlined into caller coroutine
function before coro-split pass, llvm will emits "coroutine should
have exactly one defining @llvm.coro.begin". It seems that coro-early
pass can not handle this quiet well.
So we believe that unsplited coroutine function should not be inlined.
This patch fix such issue by not inlining function if it has attribute
"coroutine.presplit" (it means the function has not been splited) to
fix this issue
TestPlan: check-llvm
Reviewed By: wenlei
Differential Revision: https://reviews.llvm.org/D85812
Summary:
If we ever assign co_await to a temporary variable, such as foo(co_await expr),
we generate AST that looks like this: MaterializedTemporaryExpr(CoawaitExpr(...)).
MaterializedTemporaryExpr would emit an intrinsics that marks the lifetime start of the
temporary storage. However such temporary storage will not be used until co_await is ready
to write the result. Marking the lifetime start way too early causes extra storage to be
put in the coroutine frame instead of the stack.
As you can see from https://godbolt.org/z/zVx_eB, the frame generated for get_big_object2 is 12K, which contains a big_object object unnecessarily.
After this patch, the frame size for get_big_object2 is now only 8K. There are still room for improvements, in particular, GCC has a 4K frame for this function. But that's a separate problem and not addressed in this patch.
The basic idea of this patch is during CoroSplit, look for every local variable in the coroutine created through AllocaInst, identify all the lifetime start/end markers and the use of the variables, and sink the lifetime.start maker to the places as close to the first-ever use as possible.
Reviewers: lewissbaker, modocache, junparser
Reviewed By: junparser
Subscribers: hiraditya, llvm-commits, rsmith, ChuanqiXu, cfe-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D82314
Summary:
For retcon and retcon.once coroutines we assume that all uses of spills
can be sunk past coro.begin. This simplifies handling of instructions
that escape the address of an alloca.
The current implementation would have issues if the address of the
alloca is escaped before coro.begin. (It also has issues with casts before and
uses of those casts after the coro.begin instruction)
%alloca_addr = alloca ...
%escape = ptrtoint %alloca_addr
coro.begin
store %escape to %alloca_addr
rdar://60272809
Subscribers: hiraditya, modocache, mgrang, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81023
See https://reviews.llvm.org/D74651 for the preallocated IR constructs
and LangRef changes.
In X86TargetLowering::LowerCall(), if a call is preallocated, record
each argument's offset from the stack pointer and the total stack
adjustment. Associate the call Value with an integer index. Store the
info in X86MachineFunctionInfo with the integer index as the key.
This adds two new target independent ISDOpcodes and two new target
dependent Opcodes corresponding to @llvm.call.preallocated.{setup,arg}.
The setup ISelDAG node takes in a chain and outputs a chain and a
SrcValue of the preallocated call Value. It is lowered to a target
dependent node with the SrcValue replaced with the integer index key by
looking in X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to an
%esp adjustment, the exact amount determined by looking in
X86MachineFunctionInfo with the integer index key.
The arg ISelDAG node takes in a chain, a SrcValue of the preallocated
call Value, and the arg index int constant. It produces a chain and the
pointer fo the arg. It is lowered to a target dependent node with the
SrcValue replaced with the integer index key by looking in
X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to a
lea of the stack pointer plus an offset determined by looking in
X86MachineFunctionInfo with the integer index key.
Force any function containing a preallocated call to use the frame
pointer.
Does not yet handle a setup without a call, or a conditional call.
Does not yet handle musttail. That requires a LangRef change first.
Tried to look at all references to inalloca and see if they apply to
preallocated. I've made preallocated versions of tests testing inalloca
whenever possible and when they make sense (e.g. not alloca related,
inalloca edge cases).
Aside from the tests added here, I checked that this codegen produces
correct code for something like
```
struct A {
A();
A(A&&);
~A();
};
void bar() {
foo(foo(foo(foo(foo(A(), 4), 5), 6), 7), 8);
}
```
by replacing the inalloca version of the .ll file with the appropriate
preallocated code. Running the executable produces the same results as
using the current inalloca implementation.
Reverted due to unexpectedly passing tests, added REQUIRES: asserts for reland.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77689
See https://reviews.llvm.org/D74651 for the preallocated IR constructs
and LangRef changes.
In X86TargetLowering::LowerCall(), if a call is preallocated, record
each argument's offset from the stack pointer and the total stack
adjustment. Associate the call Value with an integer index. Store the
info in X86MachineFunctionInfo with the integer index as the key.
This adds two new target independent ISDOpcodes and two new target
dependent Opcodes corresponding to @llvm.call.preallocated.{setup,arg}.
The setup ISelDAG node takes in a chain and outputs a chain and a
SrcValue of the preallocated call Value. It is lowered to a target
dependent node with the SrcValue replaced with the integer index key by
looking in X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to an
%esp adjustment, the exact amount determined by looking in
X86MachineFunctionInfo with the integer index key.
The arg ISelDAG node takes in a chain, a SrcValue of the preallocated
call Value, and the arg index int constant. It produces a chain and the
pointer fo the arg. It is lowered to a target dependent node with the
SrcValue replaced with the integer index key by looking in
X86MachineFunctionInfo. In
X86TargetLowering::EmitInstrWithCustomInserter() this is lowered to a
lea of the stack pointer plus an offset determined by looking in
X86MachineFunctionInfo with the integer index key.
Force any function containing a preallocated call to use the frame
pointer.
Does not yet handle a setup without a call, or a conditional call.
Does not yet handle musttail. That requires a LangRef change first.
Tried to look at all references to inalloca and see if they apply to
preallocated. I've made preallocated versions of tests testing inalloca
whenever possible and when they make sense (e.g. not alloca related,
inalloca edge cases).
Aside from the tests added here, I checked that this codegen produces
correct code for something like
```
struct A {
A();
A(A&&);
~A();
};
void bar() {
foo(foo(foo(foo(foo(A(), 4), 5), 6), 7), 8);
}
```
by replacing the inalloca version of the .ll file with the appropriate
preallocated code. Running the executable produces the same results as
using the current inalloca implementation.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77689
verifyFunction/verifyModule don't assert or error internally. They
also don't print anything if you don't pass a raw_ostream to them.
So the caller needs to check the result and ideally pass a stream
to get the messages. Otherwise they're just really expensive no-ops.
I've filed PR45965 for another instance in SLPVectorizer
that causes a lit test failure.
Differential Revision: https://reviews.llvm.org/D80106
Along the lines of D77454 and D79968. Unlike loads and stores, the
default alignment is getPrefTypeAlign, to match the existing handling in
various places, including SelectionDAG and InstCombine.
Differential Revision: https://reviews.llvm.org/D80044
Summary:
Analyses that are statefull should not be retrieved through a proxy from
an outer IR unit, as these analyses are only invalidated at the end of
the inner IR unit manager.
This patch disallows getting the outer manager and provides an API to
get a cached analysis through the proxy. If the analysis is not
stateless, the call to getCachedResult will assert.
Reviewers: chandlerc
Subscribers: mehdi_amini, eraman, hiraditya, zzheng, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D72893
This method has been commented as deprecated for a while. Remove
it and replace all uses with the equivalent getCalledOperand().
I also made a few cleanups in here. For example, to removes use
of getElementType on a pointer when we could just use getFunctionType
from the call.
Differential Revision: https://reviews.llvm.org/D78882
