[clang] [llvm] Revert "[Sema] Mark alias/ifunc targets used and consider mangled names" (PR #88919)
Mehdi Amini via cfe-commits
cfe-commits at lists.llvm.org
Tue Apr 16 08:44:59 PDT 2024
https://github.com/joker-eph created https://github.com/llvm/llvm-project/pull/88919
Reverts llvm/llvm-project#87130
Bot is broken with clang crash: https://lab.llvm.org/buildbot/#/builders/272/builds/14063/steps/6/logs/stdio
>From 271a8c2e5c8f57ab5d37f6056713dab530424470 Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph at gmail.com>
Date: Tue, 16 Apr 2024 17:44:12 +0200
Subject: [PATCH] Revert "[Sema] Mark alias/ifunc targets used and consider
mangled names"
This reverts commit 2ac562ab784c6bf04e6d3026c567d3552a735668.
---
clang/lib/Sema/CMakeLists.txt | 1 -
clang/lib/Sema/SemaDeclAttr.cpp | 44 +++++--------------
clang/test/AST/ast-dump-attr-json.cpp | 1 -
clang/test/Sema/alias-unused-win.cpp | 2 +-
clang/test/Sema/alias-unused.cpp | 16 +++----
.../llvm-project-overlay/clang/BUILD.bazel | 1 -
6 files changed, 19 insertions(+), 46 deletions(-)
diff --git a/clang/lib/Sema/CMakeLists.txt b/clang/lib/Sema/CMakeLists.txt
index a96439df664228..ab3b813a9ccd97 100644
--- a/clang/lib/Sema/CMakeLists.txt
+++ b/clang/lib/Sema/CMakeLists.txt
@@ -1,6 +1,5 @@
set(LLVM_LINK_COMPONENTS
Core
- Demangle
FrontendHLSL
FrontendOpenMP
MC
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d26f130b5774ce..b7b1fbc625a150 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -45,7 +45,6 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/STLForwardCompat.h"
#include "llvm/ADT/StringExtras.h"
-#include "llvm/Demangle/Demangle.h"
#include "llvm/IR/Assumptions.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/Support/Error.h"
@@ -1984,36 +1983,6 @@ static void handleWeakRefAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
D->addAttr(::new (S.Context) WeakRefAttr(S.Context, AL));
}
-// Mark alias/ifunc target as used. Due to name mangling, we look up the
-// demangled name ignoring parameters (not supported by microsoftDemangle
-// https://github.com/llvm/llvm-project/issues/88825). This should handle the
-// majority of use cases while leaving namespace scope names unmarked.
-static void markUsedForAliasOrIfunc(Sema &S, Decl *D, const ParsedAttr &AL,
- StringRef Str) {
- std::unique_ptr<char, llvm::FreeDeleter> Demangled;
- if (S.getASTContext().getCXXABIKind() != TargetCXXABI::Microsoft)
- Demangled.reset(llvm::itaniumDemangle(Str, /*ParseParams=*/false));
- std::unique_ptr<MangleContext> MC(S.Context.createMangleContext());
- SmallString<256> Name;
-
- const DeclarationNameInfo Target(
- &S.Context.Idents.get(Demangled ? Demangled.get() : Str), AL.getLoc());
- LookupResult LR(S, Target, Sema::LookupOrdinaryName);
- if (S.LookupName(LR, S.TUScope)) {
- for (NamedDecl *ND : LR) {
- if (MC->shouldMangleDeclName(ND)) {
- llvm::raw_svector_ostream Out(Name);
- Name.clear();
- MC->mangleName(GlobalDecl(ND), Out);
- } else {
- Name = ND->getIdentifier()->getName();
- }
- if (Name == Str)
- ND->markUsed(S.Context);
- }
- }
-}
-
static void handleIFuncAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
StringRef Str;
if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
@@ -2026,7 +1995,6 @@ static void handleIFuncAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
return;
}
- markUsedForAliasOrIfunc(S, D, AL, Str);
D->addAttr(::new (S.Context) IFuncAttr(S.Context, AL, Str));
}
@@ -2061,7 +2029,17 @@ static void handleAliasAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
}
}
- markUsedForAliasOrIfunc(S, D, AL, Str);
+ // Mark target used to prevent unneeded-internal-declaration warnings.
+ if (!S.LangOpts.CPlusPlus) {
+ // FIXME: demangle Str for C++, as the attribute refers to the mangled
+ // linkage name, not the pre-mangled identifier.
+ const DeclarationNameInfo target(&S.Context.Idents.get(Str), AL.getLoc());
+ LookupResult LR(S, target, Sema::LookupOrdinaryName);
+ if (S.LookupQualifiedName(LR, S.getCurLexicalContext()))
+ for (NamedDecl *ND : LR)
+ ND->markUsed(S.Context);
+ }
+
D->addAttr(::new (S.Context) AliasAttr(S.Context, AL, Str));
}
diff --git a/clang/test/AST/ast-dump-attr-json.cpp b/clang/test/AST/ast-dump-attr-json.cpp
index 883e584bfedf07..051c2956abfdf7 100644
--- a/clang/test/AST/ast-dump-attr-json.cpp
+++ b/clang/test/AST/ast-dump-attr-json.cpp
@@ -46,7 +46,6 @@ __thread __attribute__ ((tls_model ("local-exec"))) int tls_model_var;
// CHECK-NEXT: "tokLen": 11
// CHECK-NEXT: }
// CHECK-NEXT: },
-// CHECK-NEXT: "isUsed": true,
// CHECK-NEXT: "name": "global_decl",
// CHECK-NEXT: "mangledName": "global_decl",
// CHECK-NEXT: "type": {
diff --git a/clang/test/Sema/alias-unused-win.cpp b/clang/test/Sema/alias-unused-win.cpp
index 97d57a3bbd1e31..47c96d41175179 100644
--- a/clang/test/Sema/alias-unused-win.cpp
+++ b/clang/test/Sema/alias-unused-win.cpp
@@ -7,7 +7,7 @@ extern "C" {
static int f(void) { return 42; } // cxx-warning{{unused function 'f'}}
int g(void) __attribute__((alias("f")));
-static int foo [] = { 42, 0xDEAD };
+static int foo [] = { 42, 0xDEAD }; // cxx-warning{{variable 'foo' is not needed and will not be emitted}}
extern typeof(foo) bar __attribute__((unused, alias("foo")));
static int __attribute__((overloadable)) f0(int x) { return x; } // expected-warning{{unused function 'f0'}}
diff --git a/clang/test/Sema/alias-unused.cpp b/clang/test/Sema/alias-unused.cpp
index c0b541c880e525..dc8e46f072d74d 100644
--- a/clang/test/Sema/alias-unused.cpp
+++ b/clang/test/Sema/alias-unused.cpp
@@ -14,26 +14,24 @@ extern typeof(foo) bar __attribute__((unused, alias("foo")));
/// We report a warning in C++ mode because the internal linkage `resolver` gets
/// mangled as it does not have a language linkage. GCC does not mangle
/// `resolver` or report a warning.
-static int (*resolver(void))(void) { return f; } // cxx-warning{{unused function 'resolver'}}
+static int (*resolver(void))(void) { return f; } // expected-warning{{unused function 'resolver'}}
int ifunc(void) __attribute__((ifunc("resolver")));
-static int __attribute__((overloadable)) f0(int x) { return x; }
+static int __attribute__((overloadable)) f0(int x) { return x; } // expected-warning{{unused function 'f0'}}
static float __attribute__((overloadable)) f0(float x) { return x; } // expected-warning{{unused function 'f0'}}
int g0(void) __attribute__((alias("_ZL2f0i")));
#ifdef __cplusplus
-static int f1() { return 42; }
+static int f1() { return 42; } // expected-warning{{unused function 'f1'}}
int g1(void) __attribute__((alias("_ZL2f1v")));
}
-/// We demangle alias/ifunc target and mark all found functions as used.
-
-static int f2(int) { return 42; } // cxx-warning{{unused function 'f2'}}
-static int f2() { return 42; }
+static int f2(int) { return 42; } // expected-warning{{unused function 'f2'}}
+static int f2() { return 42; } // expected-warning{{unused function 'f2'}}
int g2() __attribute__((alias("_ZL2f2v")));
-static int (*resolver1())() { return f; } // cxx-warning{{unused function 'resolver1'}}
-static int (*resolver1(int))() { return f; }
+static int (*resolver1())() { return f; } // expected-warning{{unused function 'resolver1'}}
+static int (*resolver1(int))() { return f; } // expected-warning{{unused function 'resolver1'}}
int ifunc1() __attribute__((ifunc("_ZL9resolver1i")));
/// TODO: We should report "unused function" for f3(int).
diff --git a/utils/bazel/llvm-project-overlay/clang/BUILD.bazel b/utils/bazel/llvm-project-overlay/clang/BUILD.bazel
index 725ac6bb38120b..c2f77e3abca0e6 100644
--- a/utils/bazel/llvm-project-overlay/clang/BUILD.bazel
+++ b/utils/bazel/llvm-project-overlay/clang/BUILD.bazel
@@ -1136,7 +1136,6 @@ cc_library(
"//llvm:AllTargetsAsmParsers",
"//llvm:AllTargetsCodeGens",
"//llvm:Core",
- "//llvm:Demangle",
"//llvm:FrontendHLSL",
"//llvm:FrontendOpenMP",
"//llvm:MC",
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