Author: serge-sans-paille Date: 2021-11-02T09:53:49+01:00 New Revision: 6bfc85c217e443ecbde37b142a01dc7925792edc
URL: https://github.com/llvm/llvm-project/commit/6bfc85c217e443ecbde37b142a01dc7925792edc DIFF: https://github.com/llvm/llvm-project/commit/6bfc85c217e443ecbde37b142a01dc7925792edc.diff LOG: Fix inline builtin handling in case of redefinition Basically, inline builtin definition are shadowed by externally visible redefinition. This matches GCC behavior. The implementation has to workaround the fact that: 1. inline builtin are renamed at callsite during codegen, but 2. they may be shadowed by a later external definition As a consequence, during codegen, we need to walk redecls and eventually rewrite some call sites, which is totally inelegant. Differential Revision: https://reviews.llvm.org/D112059 Added: clang/test/CodeGen/strlen-inline-builtin-redecl.c clang/test/CodeGen/user-func-gnu-inline-redecl.c Modified: clang/lib/CodeGen/CodeGenFunction.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp index fc4540f26aabc..c3c2899e93ec7 100644 --- a/clang/lib/CodeGen/CodeGenFunction.cpp +++ b/clang/lib/CodeGen/CodeGenFunction.cpp @@ -1299,18 +1299,40 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, // When generating code for a builtin with an inline declaration, use a // mangled name to hold the actual body, while keeping an external definition // in case the function pointer is referenced somewhere. - if (FD->isInlineBuiltinDeclaration() && Fn) { - std::string FDInlineName = (Fn->getName() + ".inline").str(); - llvm::Module *M = Fn->getParent(); - llvm::Function *Clone = M->getFunction(FDInlineName); - if (!Clone) { - Clone = llvm::Function::Create(Fn->getFunctionType(), - llvm::GlobalValue::InternalLinkage, - Fn->getAddressSpace(), FDInlineName, M); - Clone->addFnAttr(llvm::Attribute::AlwaysInline); + if (Fn) { + if (FD->isInlineBuiltinDeclaration()) { + std::string FDInlineName = (Fn->getName() + ".inline").str(); + llvm::Module *M = Fn->getParent(); + llvm::Function *Clone = M->getFunction(FDInlineName); + if (!Clone) { + Clone = llvm::Function::Create(Fn->getFunctionType(), + llvm::GlobalValue::InternalLinkage, + Fn->getAddressSpace(), FDInlineName, M); + Clone->addFnAttr(llvm::Attribute::AlwaysInline); + } + Fn->setLinkage(llvm::GlobalValue::ExternalLinkage); + Fn = Clone; + } + + // Detect the unusual situation where an inline version is shadowed by a + // non-inline version. In that case we should pick the external one + // everywhere. That's GCC behavior too. Unfortunately, I cannot find a way + // to detect that situation before we reach codegen, so do some late + // replacement. + else { + for (const FunctionDecl *PD = FD->getPreviousDecl(); PD; + PD = PD->getPreviousDecl()) { + if (LLVM_UNLIKELY(PD->isInlineBuiltinDeclaration())) { + std::string FDInlineName = (Fn->getName() + ".inline").str(); + llvm::Module *M = Fn->getParent(); + if (llvm::Function *Clone = M->getFunction(FDInlineName)) { + Clone->replaceAllUsesWith(Fn); + Clone->eraseFromParent(); + } + break; + } + } } - Fn->setLinkage(llvm::GlobalValue::ExternalLinkage); - Fn = Clone; } // Check if we should generate debug info for this function. diff --git a/clang/test/CodeGen/strlen-inline-builtin-redecl.c b/clang/test/CodeGen/strlen-inline-builtin-redecl.c new file mode 100644 index 0000000000000..c89f843a71a3e --- /dev/null +++ b/clang/test/CodeGen/strlen-inline-builtin-redecl.c @@ -0,0 +1,21 @@ +// RUN: %clang_cc1 -triple x86_64 -S -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s +// +// Verifies that clang-generated *.inline are removed when shadowed by an external definition + +// CHECK-NOT: strlen.inline + +unsigned long strnlen(const char *, unsigned long); +void fortify_panic(const char *); + +extern inline __attribute__((always_inline)) __attribute__((gnu_inline)) unsigned long strlen(const char *p) { + return 1; +} +unsigned long mystrlen(char const *s) { + return strlen(s); +} +unsigned long strlen(const char *s) { + return 2; +} +unsigned long yourstrlen(char const *s) { + return strlen(s); +} diff --git a/clang/test/CodeGen/user-func-gnu-inline-redecl.c b/clang/test/CodeGen/user-func-gnu-inline-redecl.c new file mode 100644 index 0000000000000..0415cbe1e6c70 --- /dev/null +++ b/clang/test/CodeGen/user-func-gnu-inline-redecl.c @@ -0,0 +1,20 @@ +// RUN: %clang_cc1 -triple x86_64 -S -emit-llvm -O1 -o - %s | FileCheck %s +// +// Verifies that the gnu_inline version is ignored in favor of the redecl + +extern inline __attribute__((gnu_inline)) unsigned long some_size(int c) { + return 1; +} +unsigned long mycall(int s) { + // CHECK-LABEL: i64 @mycall + // CHECK: ret i64 2 + return some_size(s); +} +unsigned long some_size(int c) { + return 2; +} +unsigned long yourcall(int s) { + // CHECK-LABEL: i64 @yourcall + // CHECK: ret i64 2 + return some_size(s); +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
