From 5d0f7af3dc42d7bc843858317fba3bb91c44d68f Mon Sep 17 00:00:00 2001
From: Tom Roeder <tmroeder@google.com>
Date: Thu, 5 Jun 2014 19:29:43 +0000
Subject: Add a new attribute called 'jumptable' that creates jump-instruction
 tables for functions marked with this attribute. It includes a pass that
 rewrites all indirect calls to jumptable functions to pass through these
 tables.

This also adds backend support for generating the jump-instruction tables on ARM and X86.
Note that since the jumptable attribute creates a second function pointer for a
function, any function marked with jumptable must also be marked with unnamed_addr.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210280 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/IR/Attributes.cpp |  3 +++
 lib/IR/Verifier.cpp   | 11 ++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

(limited to 'lib/IR')

diff --git a/lib/IR/Attributes.cpp b/lib/IR/Attributes.cpp
index a9074bb294..58475e2d3c 100644
--- a/lib/IR/Attributes.cpp
+++ b/lib/IR/Attributes.cpp
@@ -173,6 +173,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
     return "inlinehint";
   if (hasAttribute(Attribute::InReg))
     return "inreg";
+  if (hasAttribute(Attribute::JumpTable))
+    return "jumptable";
   if (hasAttribute(Attribute::MinSize))
     return "minsize";
   if (hasAttribute(Attribute::Naked))
@@ -395,6 +397,7 @@ uint64_t AttributeImpl::getAttrMask(Attribute::AttrKind Val) {
   case Attribute::OptimizeNone:    return 1ULL << 42;
   case Attribute::InAlloca:        return 1ULL << 43;
   case Attribute::NonNull:         return 1ULL << 44;
+  case Attribute::JumpTable:       return 1ULL << 45;
   }
   llvm_unreachable("Unsupported attribute type");
 }
diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index 6da8014a22..46beb13622 100644
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -735,7 +735,8 @@ void Verifier::VerifyAttributeTypes(AttributeSet Attrs, unsigned Idx,
         I->getKindAsEnum() == Attribute::Builtin ||
         I->getKindAsEnum() == Attribute::NoBuiltin ||
         I->getKindAsEnum() == Attribute::Cold ||
-        I->getKindAsEnum() == Attribute::OptimizeNone) {
+        I->getKindAsEnum() == Attribute::OptimizeNone ||
+        I->getKindAsEnum() == Attribute::JumpTable) {
       if (!isFunction) {
         CheckFailed("Attribute '" + I->getAsString() +
                     "' only applies to functions!", V);
@@ -909,6 +910,14 @@ void Verifier::VerifyFunctionAttrs(FunctionType *FT, AttributeSet Attrs,
                                 Attribute::MinSize),
             "Attributes 'minsize and optnone' are incompatible!", V);
   }
+
+  if (Attrs.hasAttribute(AttributeSet::FunctionIndex,
+                         Attribute::JumpTable)) {
+    const GlobalValue *GV = cast<GlobalValue>(V);
+    Assert1(GV->hasUnnamedAddr(),
+            "Attribute 'jumptable' requires 'unnamed_addr'", V);
+
+  }
 }
 
 void Verifier::VerifyBitcastType(const Value *V, Type *DestTy, Type *SrcTy) {
-- 
cgit v1.2.3