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Add a dereferenceable attribute

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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).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213385 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2014-07-18 15:51:28 +00:00
parent a11bf68f6c
commit 11af4b49b2
22 changed files with 388 additions and 18 deletions
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45
lib/AsmParser/LLParser.cpp
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@ -1052,6 +1052,7 @@ bool LLParser::ParseFnAttributeValuePairs(AttrBuilder &B,
"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 @@ bool LLParser::ParseUInt32(unsigned &Val) {
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 @@ bool LLParser::ParseOptionalParamAttrs(AttrBuilder &B) {
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 @@ bool LLParser::ParseOptionalReturnAttrs(AttrBuilder &B) {
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 @@ bool LLParser::ParseOptionalAlignment(unsigned &Alignment) {
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