[clang] 352e36e - [Coroutines] Remove unused coroutine builtin/intrinsics llvm.coro.param (NFC-ish)
Chuanqi Xu via cfe-commits
cfe-commits at lists.llvm.org
Wed Dec 8 22:40:46 PST 2021
Author: Chuanqi Xu
Date: 2021-12-09T14:40:25+08:00
New Revision: 352e36e10d2cff310cacfc98aab39d508682e61d
URL: https://github.com/llvm/llvm-project/commit/352e36e10d2cff310cacfc98aab39d508682e61d
DIFF: https://github.com/llvm/llvm-project/commit/352e36e10d2cff310cacfc98aab39d508682e61d.diff
LOG: [Coroutines] Remove unused coroutine builtin/intrinsics llvm.coro.param (NFC-ish)
I found that the coroutine intrinsic llvm.coro.param in documentation
(https://llvm.org/docs/Coroutines.html#id101) didn't get used actually
since there isn't lowering codes in LLVM. I also checked the
implementation of libstdc++ and libc++. Both of them didn't use
llvm.coro.param. So I am pretty sure that the llvm.coro.param intrinsic
is unused. I think it would be better t to remove it to avoid possible
misleading understandings.
Note: according to [class.copy.elision]/p1.3, this optimization is
allowed by the C++ language specification. Let's make it someday.
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D115222
Added:
Modified:
clang/docs/LanguageExtensions.rst
clang/include/clang/Basic/Builtins.def
clang/lib/CodeGen/CGBuiltin.cpp
clang/test/CodeGenCoroutines/coro-builtins.c
llvm/docs/Coroutines.rst
llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
llvm/include/llvm/IR/Intrinsics.td
llvm/lib/Transforms/Coroutines/Coroutines.cpp
Removed:
################################################################################
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index e2c724e91d7d4..24e85d336ef13 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -3007,7 +3007,6 @@ an appropriate value during the emission.
void *__builtin_coro_begin(void *memory)
void __builtin_coro_end(void *coro_frame, bool unwind)
char __builtin_coro_suspend(bool final)
- bool __builtin_coro_param(void *original, void *copy)
Note that there is no builtin matching the `llvm.coro.save` intrinsic. LLVM
automatically will insert one if the first argument to `llvm.coro.suspend` is
diff --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
index 162660518f8bb..7ef550e5d81af 100644
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -1612,7 +1612,6 @@ LANGBUILTIN(__builtin_coro_alloc, "b", "n", COR_LANG)
LANGBUILTIN(__builtin_coro_begin, "v*v*", "n", COR_LANG)
LANGBUILTIN(__builtin_coro_end, "bv*Ib", "n", COR_LANG)
LANGBUILTIN(__builtin_coro_suspend, "cIb", "n", COR_LANG)
-LANGBUILTIN(__builtin_coro_param, "bv*v*", "n", COR_LANG)
// OpenCL v2.0 s6.13.16, s9.17.3.5 - Pipe functions.
// We need the generic prototype, since the packet type could be anything.
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index efe41f60fb520..5a12231541562 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -4702,8 +4702,6 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
return EmitCoroutineIntrinsic(E, Intrinsic::coro_end);
case Builtin::BI__builtin_coro_suspend:
return EmitCoroutineIntrinsic(E, Intrinsic::coro_suspend);
- case Builtin::BI__builtin_coro_param:
- return EmitCoroutineIntrinsic(E, Intrinsic::coro_param);
// OpenCL v2.0 s6.13.16.2, Built-in pipe read and write functions
case Builtin::BIread_pipe:
diff --git a/clang/test/CodeGenCoroutines/coro-builtins.c b/clang/test/CodeGenCoroutines/coro-builtins.c
index 9800eef0ed819..67a97b691d59e 100644
--- a/clang/test/CodeGenCoroutines/coro-builtins.c
+++ b/clang/test/CodeGenCoroutines/coro-builtins.c
@@ -5,9 +5,7 @@ void *myAlloc(long long);
// CHECK-LABEL: f(
void f(int n) {
// CHECK: %n.addr = alloca i32
- // CHECK: %n_copy = alloca i32
// CHECK: %promise = alloca i32
- int n_copy;
int promise;
// CHECK: %[[PROM_ADDR:.+]] = bitcast i32* %promise to i8*
@@ -45,9 +43,4 @@ void f(int n) {
// CHECK-NEXT: call i8 @llvm.coro.suspend(token none, i1 true)
__builtin_coro_suspend(1);
-
- // CHECK-NEXT: %[[N_ADDR:.+]] = bitcast i32* %n.addr to i8*
- // CHECK-NEXT: %[[N_COPY_ADDR:.+]] = bitcast i32* %n_copy to i8*
- // CHECK-NEXT: call i1 @llvm.coro.param(i8* %[[N_ADDR]], i8* %[[N_COPY_ADDR]])
- __builtin_coro_param(&n, &n_copy);
}
diff --git a/llvm/docs/Coroutines.rst b/llvm/docs/Coroutines.rst
index 8ea40563546ab..09d44e6be16bf 100644
--- a/llvm/docs/Coroutines.rst
+++ b/llvm/docs/Coroutines.rst
@@ -1644,89 +1644,6 @@ a call to ``llvm.coro.suspend.retcon`` after resuming abnormally.
In a yield-once coroutine, it is undefined behavior if the coroutine
executes a call to ``llvm.coro.suspend.retcon`` after resuming in any way.
-.. _coro.param:
-
-'llvm.coro.param' Intrinsic
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-::
-
- declare i1 @llvm.coro.param(i8* <original>, i8* <copy>)
-
-Overview:
-"""""""""
-
-The '``llvm.coro.param``' is used by a frontend to mark up the code used to
-construct and destruct copies of the parameters. If the optimizer discovers that
-a particular parameter copy is not used after any suspends, it can remove the
-construction and destruction of the copy by replacing corresponding coro.param
-with `i1 false` and replacing any use of the `copy` with the `original`.
-
-Arguments:
-""""""""""
-
-The first argument points to an `alloca` storing the value of a parameter to a
-coroutine.
-
-The second argument points to an `alloca` storing the value of the copy of that
-parameter.
-
-Semantics:
-""""""""""
-
-The optimizer is free to always replace this intrinsic with `i1 true`.
-
-The optimizer is also allowed to replace it with `i1 false` provided that the
-parameter copy is only used prior to control flow reaching any of the suspend
-points. The code that would be DCE'd if the `coro.param` is replaced with
-`i1 false` is not considered to be a use of the parameter copy.
-
-The frontend can emit this intrinsic if its language rules allow for this
-optimization.
-
-Example:
-""""""""
-Consider the following example. A coroutine takes two parameters `a` and `b`
-that has a destructor and a move constructor.
-
-.. code-block:: c++
-
- struct A { ~A(); A(A&&); bool foo(); void bar(); };
-
- task<int> f(A a, A b) {
- if (a.foo())
- return 42;
-
- a.bar();
- co_await read_async(); // introduces suspend point
- b.bar();
- }
-
-Note that, uses of `b` is used after a suspend point and thus must be copied
-into a coroutine frame, whereas `a` does not have to, since it never used
-after suspend.
-
-A frontend can create parameter copies for `a` and `b` as follows:
-
-.. code-block:: text
-
- task<int> f(A a', A b') {
- a = alloca A;
- b = alloca A;
- // move parameters to its copies
- if (coro.param(a', a)) A::A(a, A&& a');
- if (coro.param(b', b)) A::A(b, A&& b');
- ...
- // destroy parameters copies
- if (coro.param(a', a)) A::~A(a);
- if (coro.param(b', b)) A::~A(b);
- }
-
-The optimizer can replace coro.param(a',a) with `i1 false` and replace all uses
-of `a` with `a'`, since it is not used after suspend.
-
-The optimizer must replace coro.param(b', b) with `i1 true`, since `b` is used
-after suspend and therefore, it has to reside in the coroutine frame.
-
Coroutine Transformation Passes
===============================
CoroEarly
diff --git a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
index 0fafadf05be17..051f519a50d7e 100644
--- a/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ b/llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -625,7 +625,6 @@ class TargetTransformInfoImplBase {
case Intrinsic::coro_frame:
case Intrinsic::coro_size:
case Intrinsic::coro_suspend:
- case Intrinsic::coro_param:
case Intrinsic::coro_subfn_addr:
// These intrinsics don't actually represent code after lowering.
return 0;
diff --git a/llvm/include/llvm/IR/Intrinsics.td b/llvm/include/llvm/IR/Intrinsics.td
index dcd3f12245e99..138770030ebbe 100644
--- a/llvm/include/llvm/IR/Intrinsics.td
+++ b/llvm/include/llvm/IR/Intrinsics.td
@@ -1282,10 +1282,6 @@ def int_coro_alloca_alloc : Intrinsic<[llvm_token_ty],
def int_coro_alloca_get : Intrinsic<[llvm_ptr_ty], [llvm_token_ty], []>;
def int_coro_alloca_free : Intrinsic<[], [llvm_token_ty], []>;
-def int_coro_param : Intrinsic<[llvm_i1_ty], [llvm_ptr_ty, llvm_ptr_ty],
- [IntrNoMem, ReadNone<ArgIndex<0>>,
- ReadNone<ArgIndex<1>>]>;
-
// Coroutine Manipulation Intrinsics.
def int_coro_resume : Intrinsic<[], [llvm_ptr_ty], [Throws]>;
diff --git a/llvm/lib/Transforms/Coroutines/Coroutines.cpp b/llvm/lib/Transforms/Coroutines/Coroutines.cpp
index e4883ef89db7b..fba8b03e44ba7 100644
--- a/llvm/lib/Transforms/Coroutines/Coroutines.cpp
+++ b/llvm/lib/Transforms/Coroutines/Coroutines.cpp
@@ -141,7 +141,6 @@ static bool isCoroutineIntrinsicName(StringRef Name) {
"llvm.coro.id.retcon",
"llvm.coro.id.retcon.once",
"llvm.coro.noop",
- "llvm.coro.param",
"llvm.coro.prepare.async",
"llvm.coro.prepare.retcon",
"llvm.coro.promise",
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