https://github.com/ahatanak created
https://github.com/llvm/llvm-project/pull/96944
Users who don't need the signature string to be emitted can use the flag to
reduce code size.
rdar://121933818
>From 5f71f113b27482114904eae8234c6ebc17eef5a4 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahata...@gmail.com>
Date: Tue, 25 Jun 2024 19:37:46 -0700
Subject: [PATCH] [CodeGen] Add a flag to disable emitting block signature
strings
Users who don't need the signature string to be emitted can use the flag
to reduce code size.
rdar://121933818
---
clang/docs/ReleaseNotes.rst | 5 ++++
clang/include/clang/Basic/CodeGenOptions.def | 1 +
clang/include/clang/Driver/Options.td | 5 ++++
clang/lib/CodeGen/CGBlocks.cpp | 24 +++++++++++++-------
clang/lib/Driver/ToolChains/Clang.cpp | 3 +++
clang/test/CodeGen/blocks.c | 12 ++++++----
clang/test/CodeGenObjC/blocks.m | 8 +++++--
7 files changed, 44 insertions(+), 14 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index df579ae398c5e..f1fe826edc0ab 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -419,6 +419,11 @@ New Compiler Flags
Matches MSVC behaviour by defining ``__STDC__`` to ``1`` when
MSVC compatibility mode is used. It has no effect for C++ code.
+- ``-fdisable-block-signature-string`` instructs clang not to emit the
signature
+ string for blocks. Disabling the string can potentially break existing code
+ that relies on it. Users should carefully consider this possibiilty when
using
+ the flag.
+
Deprecated Compiler Flags
-------------------------
diff --git a/clang/include/clang/Basic/CodeGenOptions.def
b/clang/include/clang/Basic/CodeGenOptions.def
index e3f6da4a84f69..d8738541266d5 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -187,6 +187,7 @@ CODEGENOPT(NoImplicitFloat , 1, 0) ///< Set when
-mno-implicit-float is enable
CODEGENOPT(NullPointerIsValid , 1, 0) ///< Assume Null pointer deference is
defined.
CODEGENOPT(OpenCLCorrectlyRoundedDivSqrt, 1, 0) ///<
-cl-fp32-correctly-rounded-divide-sqrt
CODEGENOPT(HIPCorrectlyRoundedDivSqrt, 1, 1) ///<
-fno-hip-fp32-correctly-rounded-divide-sqrt
+CODEGENOPT(DisableBlockSignatureString, 1, 0) ///< Set when
-fdisable-block-signature-string is enabled.
CODEGENOPT(HIPSaveKernelArgName, 1, 0) ///< Set when -fhip-kernel-arg-name is
enabled.
CODEGENOPT(UniqueInternalLinkageNames, 1, 0) ///< Internal Linkage symbols get
unique names.
CODEGENOPT(SplitMachineFunctions, 1, 0) ///< Split machine functions using
profile information.
diff --git a/clang/include/clang/Driver/Options.td
b/clang/include/clang/Driver/Options.td
index dd55838dcf384..53a5a918cf52d 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -3477,6 +3477,11 @@ defm objc_avoid_heapify_local_blocks :
BoolFOption<"objc-avoid-heapify-local-blo
PosFlag<SetTrue, [], [ClangOption], "Try">,
NegFlag<SetFalse, [], [ClangOption], "Don't try">,
BothFlags<[], [CC1Option], " to avoid heapifying local blocks">>;
+defm disable_block_signature_string :
BoolFOption<"disable-block-signature-string",
+ CodeGenOpts<"DisableBlockSignatureString">, DefaultFalse,
+ PosFlag<SetTrue, [], [ClangOption], "Disable">,
+ NegFlag<SetFalse, [], [ClangOption], "Don't disable">,
+ BothFlags<[], [CC1Option], " block signature string)">>;
def fomit_frame_pointer : Flag<["-"], "fomit-frame-pointer">, Group<f_Group>,
Visibility<[ClangOption, FlangOption]>,
diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index 5dac1cd425bf6..241d6fc2a0c95 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -121,11 +121,15 @@ static std::string getBlockDescriptorName(const
CGBlockInfo &BlockInfo,
Name += "_";
}
- std::string TypeAtEncoding =
- CGM.getContext().getObjCEncodingForBlock(BlockInfo.getBlockExpr());
- /// Replace occurrences of '@' with '\1'. '@' is reserved on ELF platforms as
- /// a separator between symbol name and symbol version.
- std::replace(TypeAtEncoding.begin(), TypeAtEncoding.end(), '@', '\1');
+ std::string TypeAtEncoding;
+
+ if (!CGM.getCodeGenOpts().DisableBlockSignatureString) {
+ TypeAtEncoding =
+ CGM.getContext().getObjCEncodingForBlock(BlockInfo.getBlockExpr());
+ /// Replace occurrences of '@' with '\1'. '@' is reserved on ELF platforms
+ /// as a separator between symbol name and symbol version.
+ std::replace(TypeAtEncoding.begin(), TypeAtEncoding.end(), '@', '\1');
+ }
Name += "e" + llvm::to_string(TypeAtEncoding.size()) + "_" + TypeAtEncoding;
Name += "l" + CGM.getObjCRuntime().getRCBlockLayoutStr(CGM, BlockInfo);
return Name;
@@ -201,9 +205,13 @@ static llvm::Constant *buildBlockDescriptor(CodeGenModule
&CGM,
}
// Signature. Mandatory ObjC-style method descriptor @encode sequence.
- std::string typeAtEncoding =
- CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
- elements.add(CGM.GetAddrOfConstantCString(typeAtEncoding).getPointer());
+ if (CGM.getCodeGenOpts().DisableBlockSignatureString) {
+ elements.addNullPointer(i8p);
+ } else {
+ std::string typeAtEncoding =
+ CGM.getContext().getObjCEncodingForBlock(blockInfo.getBlockExpr());
+ elements.add(CGM.GetAddrOfConstantCString(typeAtEncoding).getPointer());
+ }
// GC layout.
if (C.getLangOpts().ObjC) {
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp
b/clang/lib/Driver/ToolChains/Clang.cpp
index c0f6bc0c2e45a..38d510be85b14 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5734,6 +5734,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction
&JA,
Args.AddLastArg(CmdArgs, options::OPT_fexperimental_omit_vtable_rtti,
options::OPT_fno_experimental_omit_vtable_rtti);
+ Args.AddLastArg(CmdArgs, options::OPT_fdisable_block_signature_string,
+ options::OPT_fno_disable_block_signature_string);
+
// Handle segmented stacks.
Args.addOptInFlag(CmdArgs, options::OPT_fsplit_stack,
options::OPT_fno_split_stack);
diff --git a/clang/test/CodeGen/blocks.c b/clang/test/CodeGen/blocks.c
index 8f947fcdfccb2..09efee257766e 100644
--- a/clang/test/CodeGen/blocks.c
+++ b/clang/test/CodeGen/blocks.c
@@ -1,7 +1,11 @@
-// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm
-Wno-strict-prototypes -o - -fblocks | FileCheck %s
-
-// CHECK: @{{.*}} = internal constant { i32, i32, ptr, ptr, ptr, ptr } { i32
0, i32 24, ptr @__copy_helper_block_4_20r, ptr @__destroy_helper_block_4_20r,
ptr @{{.*}}, ptr null }, align 4
-// CHECK: @[[BLOCK_DESCRIPTOR_TMP21:.*]] = internal constant { i32, i32, ptr,
ptr, ptr, ptr } { i32 0, i32 24, ptr @__copy_helper_block_4_20r, ptr
@__destroy_helper_block_4_20r, ptr @{{.*}}, ptr null }, align 4
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm
-Wno-strict-prototypes -o - -fblocks | FileCheck --check-prefix=CHECK
--check-prefix=SIG_STR %s
+// RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm
-Wno-strict-prototypes -o - -fblocks -fdisable-block-signature-string |
FileCheck --check-prefix=CHECK --check-prefix=NO_SIG_STR %s
+
+// SIG_STR: @[[STR:.*]] = private unnamed_addr constant [6 x i8] c"v4@?0\00",
align 1
+// SIG_STR: @{{.*}} = internal constant { i32, i32, ptr, ptr, ptr, ptr } { i32
0, i32 24, ptr @__copy_helper_block_4_20r, ptr @__destroy_helper_block_4_20r,
ptr @[[STR]], ptr null }, align 4
+// SIG_STR: @[[BLOCK_DESCRIPTOR_TMP21:.*]] = internal constant { i32, i32,
ptr, ptr, ptr, ptr } { i32 0, i32 24, ptr @__copy_helper_block_4_20r, ptr
@__destroy_helper_block_4_20r, ptr @[[STR]], ptr null }, align 4
+// NO_SIG_STR: @{{.*}} = internal constant { i32, i32, ptr, ptr, ptr, ptr } {
i32 0, i32 24, ptr @__copy_helper_block_4_20r, ptr
@__destroy_helper_block_4_20r, ptr null, ptr null }, align 4
+// NO_SIG_STR: @[[BLOCK_DESCRIPTOR_TMP21:.*]] = internal constant { i32, i32,
ptr, ptr, ptr, ptr } { i32 0, i32 24, ptr @__copy_helper_block_4_20r, ptr
@__destroy_helper_block_4_20r, ptr null, ptr null }, align 4
void (^f)(void) = ^{};
diff --git a/clang/test/CodeGenObjC/blocks.m b/clang/test/CodeGenObjC/blocks.m
index f82801239ad36..cd767b4cea191 100644
--- a/clang/test/CodeGenObjC/blocks.m
+++ b/clang/test/CodeGenObjC/blocks.m
@@ -1,9 +1,13 @@
-// RUN: %clang_cc1 -triple i386-apple-darwin9
-fobjc-runtime=macosx-fragile-10.5 -emit-llvm -fblocks -Wno-strict-prototypes
-o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i386-apple-darwin9
-fobjc-runtime=macosx-fragile-10.5 -emit-llvm -fblocks -Wno-strict-prototypes
-o - %s | FileCheck --check-prefix=CHECK --check-prefix=SIG_STR %s
+// RUN: %clang_cc1 -triple i386-apple-darwin9
-fobjc-runtime=macosx-fragile-10.5 -emit-llvm -fblocks -Wno-strict-prototypes
-fdisable-block-signature-string -o - %s | FileCheck --check-prefix=CHECK
--check-prefix=NO_SIG_STR %s
// Check that there is only one capture (20o) in the copy/dispose function
// names.
-// CHECK: @[[BLOCK_DESCRIPTOR0:.*]] = linkonce_odr hidden unnamed_addr
constant { i32, i32, ptr, ptr, ptr, i32 } { i32 0, i32 28, ptr
@__copy_helper_block_4_20o, ptr @__destroy_helper_block_4_20o, ptr @{{.*}}, i32
512 },
+// SIG_STR: @[[STR3:.*]] = private unnamed_addr constant [6 x i8] c"v4@?0\00",
align 1
+// SIG_STR: @[[BLOCK_DESCRIPTOR0:"__block_descriptor_28_4_20o_e5_v4\\01\?0l"]]
= linkonce_odr hidden unnamed_addr constant { i32, i32, ptr, ptr, ptr, i32 } {
i32 0, i32 28, ptr @__copy_helper_block_4_20o, ptr
@__destroy_helper_block_4_20o, ptr @[[STR3]], i32 512 },
+// NO_SIG_STR: @[[BLOCK_DESCRIPTOR0:__block_descriptor_28_4_20o_e0_l]] =
linkonce_odr hidden unnamed_addr constant { i32, i32, ptr, ptr, ptr, i32 } {
i32 0, i32 28, ptr @__copy_helper_block_4_20o, ptr
@__destroy_helper_block_4_20o, ptr null, i32 512 },
+
void (^gb0)(void);
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