[Driver][CodeGen] Support -fpatchable-function-entry=N,M and __attribute__((patchable_function_entry(N,M))) where M>0

[merge_guards_bot]

Unit tests: fail. 62040 tests passed, 2 failed and 783 were skipped.

failed: Clang.CodeGen/patchable-function-entry.c
failed: Clang.Driver/fpatchable-function-entry.c

clang-tidy: unknown.

clang-format: fail. Please format your changes with clang-format by running git-clang-format HEAD^ or applying this patch.

Build artifacts: diff.json, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

[nickdesaulniers]

LGTM, thanks for the patch!

[MaskRay]

Improve tests

[merge_guards_bot]

Unit tests: fail. 62081 tests passed, 2 failed and 784 were skipped.

failed: Clang.Driver/cc-print-options.c
failed: Clang.Driver/fpatchable-function-entry.c

clang-tidy: unknown.

clang-format: fail. Please format your changes with clang-format by running git-clang-format HEAD^ or applying this patch.

Build artifacts: diff.json, clang-format.patch, CMakeCache.txt, console-log.txt, test-results.xml

[MaskRay]

Fix Driver test

[merge_guards_bot]

Unit tests: unknown.

clang-tidy: unknown.

clang-format: unknown.

Build artifacts: diff.json, console-log.txt

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

clang/include/clang/Basic/AttrDocs.td

 
 def PatchableFunctionEntryDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{
 ``__attribute__((patchable_function_entry(N,M)))`` is used to generate M NOPs
 before the function entry and N-M NOPs after the function entry. This attribute
 takes precedence over the command line option ``-fpatchable-function-entry=N,M``.
 ``M`` defaults to 0 if omitted.
-
-Currently, only M=0 is supported.
 }];
 }
 
 def TransparentUnionDocs : Documentation {
   let Category = DocCatDecl;
   let Content = [{
 This attribute can be applied to a union to change the behaviour of calls to
 functions that have an argument with a transparent union type. The compiler

clang/include/clang/Basic/CodeGenOptions.def

 CODEGENOPT(XRayIgnoreLoops , 1, 0)
 
 
 ///< Set the minimum number of instructions in a function to determine selective
 ///< XRay instrumentation.
 VALUE_CODEGENOPT(XRayInstructionThreshold , 32, 200)
 
 VALUE_CODEGENOPT(PatchableFunctionEntryCount , 32, 0) ///< Number of NOPs at function entry
+VALUE_CODEGENOPT(PatchableFunctionEntryOffset , 32, 0)
 
 CODEGENOPT(InstrumentForProfiling , 1, 0) ///< Set when -pg is enabled.
 CODEGENOPT(CallFEntry , 1, 0) ///< Set when -mfentry is enabled.
 CODEGENOPT(MNopMCount , 1, 0) ///< Set when -mnop-mcount is enabled.
 CODEGENOPT(RecordMCount , 1, 0) ///< Set when -mrecord-mcount is enabled.
 CODEGENOPT(PackedStack , 1, 0) ///< Set when -mpacked-stack is enabled.
 CODEGENOPT(LessPreciseFPMAD  , 1, 0) ///< Enable less precise MAD instructions to
                                      ///< be generated.

clang/include/clang/Basic/DiagnosticDriverKinds.td

def warn_drv_unsupported_pic_with_mabicalls : Warning<
   InGroup<OptionIgnored>;
 def err_drv_unsupported_noabicalls_pic : Error<
   "position-independent code requires '-mabicalls'">;
 def err_drv_unsupported_indirect_jump_opt : Error<
   "'-mindirect-jump=%0' is unsupported with the '%1' architecture">;
 def err_drv_unknown_indirect_jump_opt : Error<
   "unknown '-mindirect-jump=' option '%0'">;
 def err_drv_unsupported_fpatchable_function_entry_argument : Error<
-  "the second argument of '-fpatchable-function-entry' must be 0 or omitted">;
+  "the second argument of '-fpatchable-function-entry' must be smaller than the first argument">;
 
 def warn_drv_unable_to_find_directory_expected : Warning<
   "unable to find %0 directory, expected to be in '%1'">,
   InGroup<InvalidOrNonExistentDirectory>, DefaultIgnore;
 
 def warn_drv_ps4_force_pic : Warning<
   "option '%0' was ignored by the PS4 toolchain, using '-fPIC'">,
   InGroup<OptionIgnored>;

clang/include/clang/Driver/CC1Options.td

def fsanitize_coverage_trace_pc_guard
     : Flag<["-"], "fsanitize-coverage-trace-pc-guard">,
       HelpText<"Enable PC tracing with guard in sanitizer coverage">;
 def fsanitize_coverage_no_prune
     : Flag<["-"], "fsanitize-coverage-no-prune">,
       HelpText<"Disable coverage pruning (i.e. instrument all blocks/edges)">;
 def fsanitize_coverage_stack_depth
     : Flag<["-"], "fsanitize-coverage-stack-depth">,
       HelpText<"Enable max stack depth tracing">;
+def fpatchable_function_entry_offset_EQ
+    : Joined<["-"], "fpatchable-function-entry-offset=">, MetaVarName<"<M>">,
+      HelpText<"Generate M NOPs before function entry">;
 def fprofile_instrument_EQ : Joined<["-"], "fprofile-instrument=">,
     HelpText<"Enable PGO instrumentation. The accepted value is clang, llvm, "
              "or none">, Values<"none,clang,llvm">;
 def fprofile_instrument_path_EQ : Joined<["-"], "fprofile-instrument-path=">,
     HelpText<"Generate instrumented code to collect execution counts into "
              "<file> (overridden by LLVM_PROFILE_FILE env var)">;
 def fprofile_instrument_use_path_EQ :
     Joined<["-"], "fprofile-instrument-use-path=">,

clang/include/clang/Driver/Options.td

 def fpack_struct_EQ : Joined<["-"], "fpack-struct=">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Specify the default maximum struct packing alignment">;
 def fmax_type_align_EQ : Joined<["-"], "fmax-type-align=">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Specify the maximum alignment to enforce on pointers lacking an explicit alignment">;
 def fno_max_type_align : Flag<["-"], "fno-max-type-align">, Group<f_Group>;
 def fpascal_strings : Flag<["-"], "fpascal-strings">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Recognize and construct Pascal-style string literals">;
 def fpatchable_function_entry_EQ : Joined<["-"], "fpatchable-function-entry=">, Group<f_Group>, Flags<[CC1Option]>,
-  HelpText<"Generate N NOPs at function entry">;
+  MetaVarName<"<N,M>">, HelpText<"Generate M NOPs before function entry and N-M NOPs after function entry">;
 def fpcc_struct_return : Flag<["-"], "fpcc-struct-return">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Override the default ABI to return all structs on the stack">;
 def fpch_preprocess : Flag<["-"], "fpch-preprocess">, Group<f_Group>;
 def fpic : Flag<["-"], "fpic">, Group<f_Group>;
 def fno_pic : Flag<["-"], "fno-pic">, Group<f_Group>;
 def fpie : Flag<["-"], "fpie">, Group<f_Group>;
 def fno_pie : Flag<["-"], "fno-pie">, Group<f_Group>;
 def fplt : Flag<["-"], "fplt">, Group<f_Group>, Flags<[CC1Option]>,

clang/lib/CodeGen/CodeGenFunction.cpp

if (const auto *XRayAttr = D->getAttr<XRayInstrumentAttr>()) {
         Fn->addFnAttr(
             "xray-instruction-threshold",
             llvm::itostr(CGM.getCodeGenOpts().XRayInstructionThreshold));
       if (CGM.getCodeGenOpts().XRayIgnoreLoops) {
         Fn->addFnAttr("xray-ignore-loops");
       }
     }
 
+    unsigned Count, Offset;
     if (const auto *Attr = D->getAttr<PatchableFunctionEntryAttr>()) {
-      // Attr->getStart is currently ignored.
-      Fn->addFnAttr("patchable-function-entry",
-                    std::to_string(Attr->getCount()));
-    } else if (unsigned Count = CGM.getCodeGenOpts().PatchableFunctionEntryCount) {
-      Fn->addFnAttr("patchable-function-entry",
-                    std::to_string(Count));
+      Count = Attr->getCount();
+      Offset = Attr->getOffset();
+    } else {
+      Count = CGM.getCodeGenOpts().PatchableFunctionEntryCount;
+      Offset = CGM.getCodeGenOpts().PatchableFunctionEntryOffset;
+    }
+    if (Count && Offset <= Count) {
+      Fn->addFnAttr("patchable-function-entry", std::to_string(Count - Offset));
+      if (Offset)
+        Fn->addFnAttr("patchable-function-prefix", std::to_string(Offset));
     }
   }
 
   // Add no-jump-tables value.
   Fn->addFnAttr("no-jump-tables",
                 llvm::toStringRef(CGM.getCodeGenOpts().NoUseJumpTables));
 
   // Add no-inline-line-tables value.

clang/lib/Driver/ToolChains/Clang.cpp

#endif
   const SanitizerArgs &Sanitize = TC.getSanitizerArgs();
   Sanitize.addArgs(TC, Args, CmdArgs, InputType);
 
   const XRayArgs &XRay = TC.getXRayArgs();
   XRay.addArgs(TC, Args, CmdArgs, InputType);
 
   if (Arg *A = Args.getLastArg(options::OPT_fpatchable_function_entry_EQ)) {
     StringRef S0 = A->getValue(), S = S0;
-    unsigned Size, Start = 0;
+    unsigned Size, Offset = 0;
     if (!Triple.isAArch64() && Triple.getArch() != llvm::Triple::x86 &&
         Triple.getArch() != llvm::Triple::x86_64)
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getAsString(Args) << TripleStr;
     else if (S.consumeInteger(10, Size) ||
              (!S.empty() && (!S.consume_front(",") ||
-                             S.consumeInteger(10, Start) || !S.empty())))
+                             S.consumeInteger(10, Offset) || !S.empty())))
       D.Diag(diag::err_drv_invalid_argument_to_option)
           << S0 << A->getOption().getName();
-    else if (Start)
+    else if (Size < Offset)
       D.Diag(diag::err_drv_unsupported_fpatchable_function_entry_argument);
-    else
+    else {
       CmdArgs.push_back(Args.MakeArgString(A->getSpelling() + Twine(Size)));
+      CmdArgs.push_back(Args.MakeArgString(
+          "-fpatchable-function-entry-offset=" + Twine(Offset)));
+    }
   }
 
   if (TC.SupportsProfiling()) {
     Args.AddLastArg(CmdArgs, options::OPT_pg);
 
     llvm::Triple::ArchType Arch = TC.getArch();
     if (Arg *A = Args.getLastArg(options::OPT_mfentry)) {
       if (Arch == llvm::Triple::systemz || TC.getTriple().isX86())

clang/lib/Frontend/CompilerInvocation.cpp

if (XRayInstrBundles.empty())
     Opts.XRayInstrumentationBundle.Mask = XRayInstrKind::All;
   else
     for (const auto &A : XRayInstrBundles)
       parseXRayInstrumentationBundle("-fxray-instrumentation-bundle=", A, Args,
                                      Diags, Opts.XRayInstrumentationBundle);
 
   Opts.PatchableFunctionEntryCount =
       getLastArgIntValue(Args, OPT_fpatchable_function_entry_EQ, 0, Diags);
+  Opts.PatchableFunctionEntryOffset = getLastArgIntValue(
+      Args, OPT_fpatchable_function_entry_offset_EQ, 0, Diags);
   Opts.InstrumentForProfiling = Args.hasArg(OPT_pg);
   Opts.CallFEntry = Args.hasArg(OPT_mfentry);
   Opts.MNopMCount = Args.hasArg(OPT_mnop_mcount);
   Opts.RecordMCount = Args.hasArg(OPT_mrecord_mcount);
   Opts.PackedStack = Args.hasArg(OPT_mpacked_stack);
   Opts.EmitOpenCLArgMetadata = Args.hasArg(OPT_cl_kernel_arg_info);
 
   if (const Arg *A = Args.getLastArg(OPT_fcf_protection_EQ)) {

clang/lib/Sema/SemaDeclAttr.cpp

static void handlePatchableFunctionEntryAttr(Sema &S, Decl *D,
                                              const ParsedAttr &AL) {
   uint32_t Count = 0, Offset = 0;
   if (!checkUInt32Argument(S, AL, AL.getArgAsExpr(0), Count, 0, true))
     return;
   if (AL.getNumArgs() == 2) {
     Expr *Arg = AL.getArgAsExpr(1);
     if (!checkUInt32Argument(S, AL, Arg, Offset, 1, true))
       return;
-    if (Offset) {
+    if (Count < Offset) {
       S.Diag(getAttrLoc(AL), diag::err_attribute_argument_out_of_range)
-          << &AL << 0 << 0 << Arg->getBeginLoc();
+          << &AL << 0 << Count << Arg->getBeginLoc();
       return;
     }
   }
   D->addAttr(::new (S.Context)
                  PatchableFunctionEntryAttr(S.Context, AL, Count, Offset));
 }
 
 static bool ArmMveAliasValid(unsigned BuiltinID, StringRef AliasName) {

clang/test/CodeGen/patchable-function-entry.c

 
 // CHECK: define void @f20() #1
 __attribute__((patchable_function_entry(2, 0))) void f20() {}
 
 // CHECK: define void @f20decl() #1
 __attribute__((patchable_function_entry(2, 0))) void f20decl();
 void f20decl() {}
 
-// OPT: define void @f() #2
+// CHECK: define void @f52() #2
+__attribute__((patchable_function_entry(5, 2))) void f52() {}
+
+// OPT: define void @f() #3
 void f() {}
 
 /// M in patchable_function_entry(N,M) is currently ignored.
 // CHECK: attributes #0 = { {{.*}} "patchable-function-entry"="0"
 // CHECK: attributes #1 = { {{.*}} "patchable-function-entry"="2"
-// OPT:   attributes #2 = { {{.*}} "patchable-function-entry"="1"
+// CHECK: attributes #2 = { {{.*}} "patchable-function-entry"="3" "patchable-function-prefix"="2"
+// OPT:   attributes #3 = { {{.*}} "patchable-function-entry"="1"

clang/test/Sema/patchable-function-entry-attr.c

 // RUN: %clang_cc1 -triple aarch64 -fsyntax-only -verify %s
 
 // expected-error@+1 {{'patchable_function_entry' attribute takes at least 1 argument}}
 __attribute__((patchable_function_entry)) void f();
 
 // expected-error@+1 {{'patchable_function_entry' attribute takes no more than 2 arguments}}
 __attribute__((patchable_function_entry(0, 0, 0))) void f();
 
 // expected-error@+1 {{'patchable_function_entry' attribute requires a non-negative integral compile time constant expression}}
 __attribute__((patchable_function_entry(-1))) void f();
 
 int i;
 // expected-error@+1 {{'patchable_function_entry' attribute requires parameter 0 to be an integer constant}}
 __attribute__((patchable_function_entry(i))) void f();
 
-// expected-error@+1 {{'patchable_function_entry' attribute requires integer constant between 0 and 0 inclusive}}
-__attribute__((patchable_function_entry(1, 1))) void f();
+// expected-error@+1 {{'patchable_function_entry' attribute requires integer constant between 0 and 2 inclusive}}
+__attribute__((patchable_function_entry(2, 3))) void f();