[clang][slh] add attribute for speculative load hardening

Summary:
The prior diff had to be reverted because there were two tests
that failed. I updated the two tests in this diff

clang/test/Misc/pragma-attribute-supported-attributes-list.test
clang/test/SemaCXX/attr-speculative-load-hardening.cpp

----- Summary from Previous Diff (Still Accurate) -----

LLVM IR already has an attribute for speculative_load_hardening. Before
this commit, when a user passed the -mspeculative-load-hardening flag to
Clang, every function would have this attribute added to it. This Clang
attribute will allow users to opt into SLH on a function by function basis.

This can be applied to functions and Objective C methods.

Reviewers: chandlerc, echristo, kristof.beyls, aaron.ballman

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D54915

llvm-svn: 347617

2 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 0ec5c7fb452..6d89f3919fd 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -1791,6 +1791,8 @@ void CodeGenModule::ConstructDefaultFnAttrList(StringRef Name, bool HasOptnone,
     if (CodeGenOpts.Backchain)
       FuncAttrs.addAttribute("backchain");
 
+    // FIXME: The interaction of this attribute with the SLH command line flag
+    // has not been determined.
     if (CodeGenOpts.SpeculativeLoadHardening)
       FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
   }
@@ -1854,6 +1856,8 @@ void CodeGenModule::ConstructAttributeList(
       FuncAttrs.addAttribute(llvm::Attribute::NoDuplicate);
     if (TargetDecl->hasAttr<ConvergentAttr>())
       FuncAttrs.addAttribute(llvm::Attribute::Convergent);
+    if (TargetDecl->hasAttr<SpeculativeLoadHardeningAttr>())
+      FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
 
     if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
       AddAttributesFromFunctionProtoType(
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 9f5325d109e..be662b9b914 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -6373,6 +6373,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_Section:
     handleSectionAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_SpeculativeLoadHardening:
+    handleSimpleAttribute<SpeculativeLoadHardeningAttr>(S, D, AL);
+    break;
   case ParsedAttr::AT_CodeSeg:
     handleCodeSegAttr(S, D, AL);
     break;