Add the allocsize attribute to LLVM.

`allocsize` is a function attribute that allows users to request that
LLVM treat arbitrary functions as allocation functions.

This patch makes LLVM accept the `allocsize` attribute, and makes
`@llvm.objectsize` recognize said attribute.

The review for this was split into two patches for ease of reviewing:
D18974 and D14933. As promised on the revisions, I'm landing both
patches as a single commit.

Differential Revision: http://reviews.llvm.org/D14933

llvm-svn: 266032

1 files changed, 39 insertions, 0 deletions

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index db87fa7..e0ce50d 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -14,6 +14,7 @@
 #include "LLParser.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/AsmParser/SlotMapping.h"
 #include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/CallingConv.h"
@@ -1051,6 +1052,15 @@ bool LLParser::ParseFnAttributeValuePairs(AttrBuilder &B,
       B.addStackAlignmentAttr(Alignment);
       continue;
     }
+    case lltok::kw_allocsize: {
+      unsigned ElemSizeArg;
+      Optional<unsigned> NumElemsArg;
+      // inAttrGrp doesn't matter; we only support allocsize(a[, b])
+      if (parseAllocSizeArguments(ElemSizeArg, NumElemsArg))
+        return true;
+      B.addAllocSizeAttr(ElemSizeArg, NumElemsArg);
+      continue;
+    }
     case lltok::kw_alwaysinline: B.addAttribute(Attribute::AlwaysInline); break;
     case lltok::kw_argmemonly: B.addAttribute(Attribute::ArgMemOnly); break;
     case lltok::kw_builtin: B.addAttribute(Attribute::Builtin); break;
@@ -1790,6 +1800,35 @@ bool LLParser::ParseOptionalCommaAlign(unsigned &Alignment,
   return false;
 }
 
+bool LLParser::parseAllocSizeArguments(unsigned &BaseSizeArg,
+                                       Optional<unsigned> &HowManyArg) {
+  Lex.Lex();
+
+  auto StartParen = Lex.getLoc();
+  if (!EatIfPresent(lltok::lparen))
+    return Error(StartParen, "expected '('");
+
+  if (ParseUInt32(BaseSizeArg))
+    return true;
+
+  if (EatIfPresent(lltok::comma)) {
+    auto HowManyAt = Lex.getLoc();
+    unsigned HowMany;
+    if (ParseUInt32(HowMany))
+      return true;
+    if (HowMany == BaseSizeArg)
+      return Error(HowManyAt,
+                   "'allocsize' indices can't refer to the same parameter");
+    HowManyArg = HowMany;
+  } else
+    HowManyArg = None;
+
+  auto EndParen = Lex.getLoc();
+  if (!EatIfPresent(lltok::rparen))
+    return Error(EndParen, "expected ')'");
+  return false;
+}
+
 /// ParseScopeAndOrdering
 ///   if isAtomic: ::= 'singlethread'? AtomicOrdering
 ///   else: ::=