Author: George Burgess IV Date: 2020-04-15T11:05:22-07:00 New Revision: 2dd17ff08165e6118e70f00e22b2c36d2d4e0a9a
URL: https://github.com/llvm/llvm-project/commit/2dd17ff08165e6118e70f00e22b2c36d2d4e0a9a DIFF: https://github.com/llvm/llvm-project/commit/2dd17ff08165e6118e70f00e22b2c36d2d4e0a9a.diff LOG: [CodeGen] only add nobuiltin to inline builtins if we'll emit them There are some inline builtin definitions that we can't emit (isTriviallyRecursive & callers go into why). Marking these nobuiltin is only useful if we actually emit the body, so don't mark these as such unless we _do_ plan on emitting that. This suboptimality was encountered in Linux (see some discussion on D71082, and https://github.com/ClangBuiltLinux/linux/issues/979). Differential Revision: https://reviews.llvm.org/D78162 Added: clang/test/CodeGen/memcpy-no-nobuiltin-if-not-emitted.c Modified: clang/lib/CodeGen/CodeGenModule.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 39aa5c1c512f..73a3212bcd47 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -1908,7 +1908,8 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F, else if (const auto *SA = FD->getAttr<SectionAttr>()) F->setSection(SA->getName()); - if (FD->isInlineBuiltinDeclaration()) { + // If we plan on emitting this inline builtin, we can't treat it as a builtin. + if (FD->isInlineBuiltinDeclaration() && shouldEmitFunction(FD)) { F->addAttribute(llvm::AttributeList::FunctionIndex, llvm::Attribute::NoBuiltin); } diff --git a/clang/test/CodeGen/memcpy-no-nobuiltin-if-not-emitted.c b/clang/test/CodeGen/memcpy-no-nobuiltin-if-not-emitted.c new file mode 100644 index 000000000000..b4c1376c5bb3 --- /dev/null +++ b/clang/test/CodeGen/memcpy-no-nobuiltin-if-not-emitted.c @@ -0,0 +1,25 @@ +// RUN: %clang_cc1 -triple x86_64-unknown-unknown -S -emit-llvm -o - %s | FileCheck %s +// +// Verifies that clang doesn't mark an inline builtin definition as `nobuiltin` +// if the builtin isn't emittable. + +typedef unsigned long size_t; + +// always_inline is used so clang will emit this body. Otherwise, we need >= +// -O1. +#define AVAILABLE_EXTERNALLY extern inline __attribute__((always_inline)) \ + __attribute__((gnu_inline)) + +AVAILABLE_EXTERNALLY void *memcpy(void *a, const void *b, size_t c) { + return __builtin_memcpy(a, b, c); +} + +// CHECK-LABEL: define void @foo +void foo(void *a, const void *b, size_t c) { + // Clang will always _emit_ this as memcpy. LLVM turns it into @llvm.memcpy + // later on if optimizations are enabled. + // CHECK: call i8* @memcpy + memcpy(a, b, c); +} + +// CHECK-NOT: nobuiltin _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
