Add a dereferenceable attribute
This attribute indicates that the parameter or return pointer is
dereferenceable. Practically speaking, loads from such a pointer within the
associated byte range are safe to speculatively execute. Such pointer
parameters are common in source languages (C++ references, for example).
llvm-svn: 213385
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index be55ac6..ac6e0e5 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -1052,6 +1052,7 @@
"invalid use of attribute on a function");
break;
case lltok::kw_byval:
+ case lltok::kw_dereferenceable:
case lltok::kw_inalloca:
case lltok::kw_nest:
case lltok::kw_noalias:
@@ -1212,6 +1213,16 @@
return false;
}
+/// ParseUInt64
+/// ::= uint64
+bool LLParser::ParseUInt64(uint64_t &Val) {
+ if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
+ return TokError("expected integer");
+ Val = Lex.getAPSIntVal().getLimitedValue();
+ Lex.Lex();
+ return false;
+}
+
/// ParseTLSModel
/// := 'localdynamic'
/// := 'initialexec'
@@ -1284,6 +1295,13 @@
continue;
}
case lltok::kw_byval: B.addAttribute(Attribute::ByVal); break;
+ case lltok::kw_dereferenceable: {
+ uint64_t Bytes;
+ if (ParseOptionalDereferenceableBytes(Bytes))
+ return true;
+ B.addDereferenceableAttr(Bytes);
+ continue;
+ }
case lltok::kw_inalloca: B.addAttribute(Attribute::InAlloca); break;
case lltok::kw_inreg: B.addAttribute(Attribute::InReg); break;
case lltok::kw_nest: B.addAttribute(Attribute::Nest); break;
@@ -1341,6 +1359,13 @@
switch (Token) {
default: // End of attributes.
return HaveError;
+ case lltok::kw_dereferenceable: {
+ uint64_t Bytes;
+ if (ParseOptionalDereferenceableBytes(Bytes))
+ return true;
+ B.addDereferenceableAttr(Bytes);
+ continue;
+ }
case lltok::kw_inreg: B.addAttribute(Attribute::InReg); break;
case lltok::kw_noalias: B.addAttribute(Attribute::NoAlias); break;
case lltok::kw_nonnull: B.addAttribute(Attribute::NonNull); break;
@@ -1606,6 +1631,26 @@
return false;
}
+/// ParseOptionalDereferenceableBytes
+/// ::= /* empty */
+/// ::= 'dereferenceable' '(' 4 ')'
+bool LLParser::ParseOptionalDereferenceableBytes(uint64_t &Bytes) {
+ Bytes = 0;
+ if (!EatIfPresent(lltok::kw_dereferenceable))
+ return false;
+ LocTy ParenLoc = Lex.getLoc();
+ if (!EatIfPresent(lltok::lparen))
+ return Error(ParenLoc, "expected '('");
+ LocTy DerefLoc = Lex.getLoc();
+ if (ParseUInt64(Bytes)) return true;
+ ParenLoc = Lex.getLoc();
+ if (!EatIfPresent(lltok::rparen))
+ return Error(ParenLoc, "expected ')'");
+ if (!Bytes)
+ return Error(DerefLoc, "dereferenceable bytes must be non-zero");
+ return false;
+}
+
/// ParseOptionalCommaAlign
/// ::=
/// ::= ',' align 4