From d2f44d8de01a635e197b3ad4dcafdab5f2b4408a Mon Sep 17 00:00:00 2001 From: Nirav Dave Date: Tue, 5 Apr 2016 17:50:43 +0000 Subject: [PATCH] Add -fno-jump-tables and-fjump-tables flags Add no-jump-tables flag to disable use of jump tables when lowering switch statements Reviewers: echristo, hans Subscribers: llvm-commits Differential Revision: http://reviews.llvm.org/D18407 llvm-svn: 265425 --- clang/include/clang/Driver/Options.td | 3 +++ clang/include/clang/Frontend/CodeGenOptions.def | 1 + clang/lib/CodeGen/CodeGenFunction.cpp | 4 ++++ clang/lib/Driver/Tools.cpp | 4 ++++ clang/lib/Frontend/CompilerInvocation.cpp | 2 ++ clang/test/CodeGen/nousejumptable.c | 8 ++++++++ 6 files changed, 22 insertions(+) create mode 100644 clang/test/CodeGen/nousejumptable.c diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 9f0ab256984f8..a1befe379bd9a 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -586,6 +586,9 @@ def fno_math_errno : Flag<["-"], "fno-math-errno">, Group; def fbracket_depth_EQ : Joined<["-"], "fbracket-depth=">, Group; def fsignaling_math : Flag<["-"], "fsignaling-math">, Group; def fno_signaling_math : Flag<["-"], "fno-signaling-math">, Group; +def fjump_tables : Flag<["-"], "fjump-tables">, Group; +def fno_jump_tables : Flag<["-"], "fno-jump-tables">, Group, Flags<[CC1Option]>, + HelpText<"Do not use jump tables for lowering switches">; def fsanitize_EQ : CommaJoined<["-"], "fsanitize=">, Group, Flags<[CC1Option, CoreOption]>, MetaVarName<"">, HelpText<"Turn on runtime checks for various forms of undefined " diff --git a/clang/include/clang/Frontend/CodeGenOptions.def b/clang/include/clang/Frontend/CodeGenOptions.def index cd5b50c52805d..283f0a21690b7 100644 --- a/clang/include/clang/Frontend/CodeGenOptions.def +++ b/clang/include/clang/Frontend/CodeGenOptions.def @@ -149,6 +149,7 @@ CODEGENOPT(UnitAtATime , 1, 1) ///< Unused. For mirroring GCC optimization ///< selection. CODEGENOPT(UnrollLoops , 1, 0) ///< Control whether loops are unrolled. CODEGENOPT(RerollLoops , 1, 0) ///< Control whether loops are rerolled. +CODEGENOPT(NoUseJumpTables , 1, 0) ///< Set when -fno-jump-tables is enabled CODEGENOPT(UnsafeFPMath , 1, 0) ///< Allow unsafe floating point optzns. CODEGENOPT(UnwindTables , 1, 0) ///< Emit unwind tables. CODEGENOPT(VectorizeBB , 1, 0) ///< Run basic block vectorizer. diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp index 71c364cabc55f..8acc256cb3fee 100644 --- a/clang/lib/CodeGen/CodeGenFunction.cpp +++ b/clang/lib/CodeGen/CodeGenFunction.cpp @@ -711,6 +711,10 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, Fn->addFnAttr(llvm::Attribute::NoInline); } + // Add no-jump-tables value. + Fn->addFnAttr("no-jump-tables", + llvm::toStringRef(CGM.getCodeGenOpts().NoUseJumpTables)); + if (getLangOpts().OpenCL) { // Add metadata for a kernel function. if (const FunctionDecl *FD = dyn_cast_or_null(D)) diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp index 824ee72dcd241..6be28290a7fbd 100644 --- a/clang/lib/Driver/Tools.cpp +++ b/clang/lib/Driver/Tools.cpp @@ -3891,6 +3891,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, A->claim(); } + if (!Args.hasFlag(options::OPT_fjump_tables, options::OPT_fno_jump_tables, + true)) + CmdArgs.push_back("-fno-jump-tables"); + if (Arg *A = Args.getLastArg(options::OPT_mregparm_EQ)) { CmdArgs.push_back("-mregparm"); CmdArgs.push_back(A->getValue()); diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp index da0b3a83be825..4d97b76d75382 100644 --- a/clang/lib/Frontend/CompilerInvocation.cpp +++ b/clang/lib/Frontend/CompilerInvocation.cpp @@ -606,6 +606,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK, Opts.MergeFunctions = Args.hasArg(OPT_fmerge_functions); + Opts.NoUseJumpTables = Args.hasArg(OPT_fno_jump_tables); + Opts.PrepareForLTO = Args.hasArg(OPT_flto, OPT_flto_EQ); const Arg *A = Args.getLastArg(OPT_flto, OPT_flto_EQ); Opts.EmitSummaryIndex = A && A->containsValue("thin"); diff --git a/clang/test/CodeGen/nousejumptable.c b/clang/test/CodeGen/nousejumptable.c new file mode 100644 index 0000000000000..91ad5818570db --- /dev/null +++ b/clang/test/CodeGen/nousejumptable.c @@ -0,0 +1,8 @@ +// RUN: %clang_cc1 -S -fno-jump-tables %s -emit-llvm -o - | FileCheck %s + +// CHECK-LABEL: main +// CHECK: attributes #0 = {{.*}}"no-jump-tables"="true"{{.*}} + +int main() { + return 0; +}