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

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D73072

(cherry picked from commit 69bf40c45fd7f6dfe11b47de42571d8bff5ef94f)

4 files changed, 22 insertions, 12 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 2bf94f697e0..648e6d9c214 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -820,13 +820,18 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
             llvm::itostr(CGM.getCodeGenOpts().XRayInstructionThreshold));
     }
 
+    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));
     }
   }
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 9b3055413e9..647465863d3 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5077,20 +5077,23 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   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()) {
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index edf1f27b7c5..4e5babdbaa0 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1103,6 +1103,8 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   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);
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 5c51b0f9b8c..849bc09063b 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -4924,9 +4924,9 @@ static void handlePatchableFunctionEntryAttr(Sema &S, Decl *D,
     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;
     }
   }